Difference between revisions of "Python-3.4.3/C2/Getting-started-with-for/English"

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Line 19: Line 19:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| At the end of this tutorial, you will be able to,
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| At the end of this tutorial, you will be able to,
  
# Use the '''for''' loop.
+
# Use the '''for loop'''.
# Use '''range()''' function.
+
# Use '''range() function'''.
  
 
|-
 
|-
Line 39: Line 39:
 
If not, see the relavant Python tutorials on http://spoken-tutorial.org
 
If not, see the relavant Python tutorials on http://spoken-tutorial.org
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| To practice this tutorial, you should know how to use lists.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| To practice this tutorial, you should know how to use '''lists'''.
  
If not, see the relevant Python tutorials on this website.
+
If not, see the relevant '''Python''' tutorials on this website.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| First let us see the syntax of '''for''' loop.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| First let us see the syntax of '''for loop'''.
  
 
|-
 
|-
Line 63: Line 63:
 
'''Highlight according to narration'''
 
'''Highlight according to narration'''
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| '''for''' statement iterates over the members of a sequence in order, executing the block each time.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 +
'''for statement''' iterates over the members of a sequence in order, executing the '''block''' each time.
  
Here the loop variable takes the value of the item inside the sequence on each iteration.
 
  
For each '''item,''' the '''loop''' '''body''' is '''executed. '''
+
Here the '''loop variable''' takes the value of the '''item''' inside the sequence on each iteration.
 +
 
 +
 
 +
For each '''item,''' the '''loop body''' is executed.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| We will see an example of '''‘For’''' loop and how to execute it.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| We will see an example of '''for loop''' and how to execute it.
  
 
|-
 
|-
Line 79: Line 82:
  
 
| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.014cm;padding-right:0.191cm;"| Let us first open the '''Terminal '''by pressing '''Ctrl+Alt+T '''keys simultaneously.  
 
| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.014cm;padding-right:0.191cm;"| Let us first open the '''Terminal '''by pressing '''Ctrl+Alt+T '''keys simultaneously.  
 +
  
 
Now, type '''ipython3''' and press '''Enter'''.  
 
Now, type '''ipython3''' and press '''Enter'''.  
Line 86: Line 90:
  
 
'''%pylab '''and press '''Enter.'''
 
'''%pylab '''and press '''Enter.'''
| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.014cm;padding-right:0.191cm;"| Let us initialise the '''pylab''' package.
+
| style="background-color:#ffffff;border:1pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.014cm;padding-right:0.191cm;"| Let us initialise the '''pylab package'''.
  
 
Type '''%pylab '''and press''' Enter.'''
 
Type '''%pylab '''and press''' Enter.'''
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|
 
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Open your '''text''' '''editor'''.
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Open your '''text''' '''editor'''.
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Open your '''text editor'''.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight according to narration
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight according to narration
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us write a '''for''' loop. Type the code as shown here:
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us write a '''for loop'''. Type the code as shown here:
  
 
|-
 
|-
Line 104: Line 108:
 
'''for num in numbers:'''
 
'''for num in numbers:'''
  
     '''print(“sqrt of”, num,'''''“is”, num**0.5)''
+
     '''print(“sqrt of”, num, '''''“is”, num**0.5)''
  
 
'''print("This is outside for-loop")'''
 
'''print("This is outside for-loop")'''
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Here the '''for''' loop iterates over a list of numbers and finds the square root of each number.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Here the loop variable iterates over a list of numbers and finds the square root of each number.
 +
 
 +
 
 +
The numbers are: 4, 9, 16, 25, and 36.
  
The numbers are: 4, 9, 16, 25, 36
 
  
 
Note that here we used two variables,
 
Note that here we used two variables,
  
* '''numbers -''' which is a list of numbers
+
* '''numbers -''' which is a '''list''' of numbers
* '''num''' - which is the element of list under consideration in each cycle of the '''for loop'''.  
+
* '''num''' - which is the element of '''list''' under consideration, in each cycle of the '''for loop'''.  
  
 
The variable names can be any of your choice.
 
The variable names can be any of your choice.
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Switch back to the editor.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the line '''print(“sqrt of”, num, “is”, num**0.5)'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us switch back to the text editor.
+
  
|-
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that a '''colon''' after the '''for statement''' indicates the starting of '''loop body'''.
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the line after '''for '''statement
+
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that a '''colon''' after the '''for''' '''statement''' '''indicates''' the starting of '''loop''' '''body'''.
 
  
Every '''statement '''in '''loop''' starts''' with 4 spaces'''
+
Every '''statement '''in '''loop''' starts with 4 spaces.
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the line after '''for '''statement
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the line '''print(“sqrt of”, num, “is”, num**0.5)'''
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| It means that, the line is a '''block''' of '''code''' in '''for loop'''.  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| It means that, the line is a '''block''' of '''code''' in '''for loop'''.  
  
In this example, it is only a single statement in the block.
+
 
 +
In this example, it is only a single '''statement''' in the '''block'''.
  
 
|-
 
|-
Line 143: Line 147:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the line '''print("This is outside for-loop")''' is not indented.  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the line '''print("This is outside for-loop")''' is not indented.  
  
It means that it is not a part of the''' for''' loop.
 
  
And the lines after that don't fall in the scope of the '''for''' loop.
+
It means that it is not a part of the''' for loop'''.
 +
 
 +
 
 +
And the lines after that don't fall in the scope of the '''for loop'''.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight indentation
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight indentation
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Thus each block is separated by the indentation level.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Thus each '''block''' is separated by the indentation level.  
 +
 
  
 
This marks the importance of '''white-spaces''' in '''Python'''.
 
This marks the importance of '''white-spaces''' in '''Python'''.
Line 155: Line 162:
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Save the file as sqrt_num_list.py
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Save the file as sqrt_num_list.py
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Save the file as '''sqrt_num_list.py '''in the''' home '''directory'''.'''
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Save the file as '''sqrt_num_list.py '''in the''' home directory'''.
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| switch back to your terminal
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| switch back to your terminal. Clear the terminal
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now switch back to your terminal.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now switch back to your '''terminal'''.
 +
 
 +
 
 +
Let us clear the '''terminal'''.
  
 
|-
 
|-
Line 182: Line 192:
 
This is outside for-loop
 
This is outside for-loop
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Run the script using the '''run''' command as,
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Run the script using the '''run''' command as-
  
 
'''''percent'' run ''minus'' i filename '''and press '''Enter.'''
 
'''''percent'' run ''minus'' i filename '''and press '''Enter.'''
  
We get the square root of the given numbers executed by the for loop.
+
|-
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the output
 +
 
 +
%run -i sqrt_num_list.py
 +
 
 +
sqrt of 4 is 2.0
 +
 
 +
sqrt of 9 is 3.0
 +
 
 +
sqrt of 16 is 4.0
 +
 
 +
sqrt of 25 is 5.0
 +
 
 +
sqrt of 36 is 6.0
 +
 
 +
This is outside for-loop
 +
 
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| We get the square root of the given numbers executed by the '''for loop'''.
 +
 
  
This is the print statement output executed after the for loop.
+
This is the '''print statement''' output executed after the '''for loop'''.
  
 
|-
 
|-
Line 196: Line 224:
  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
* Use the same example we used in sqrt_num_list.py
+
* Use the same example we used in '''sqrt_num_list.py'''
  
* Type each line of the code in the '''IPython''' '''interpreter prompt. '''
+
* Type each line of the code in the '''IPython interpreter prompt. '''
  
 
* Skip the line: '''print("This is outside for-loop")'''
 
* Skip the line: '''print("This is outside for-loop")'''
Line 204: Line 232:
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
 +
Type
  
 
'''<nowiki>numbers = [4, 9, 16, 25, 36]</nowiki>'''
 
'''<nowiki>numbers = [4, 9, 16, 25, 36]</nowiki>'''
  
'''for num in numbers: '''Press '''Enter'''
+
'''for num in numbers:  
 +
 
 +
'''Press '''Enter'''
 +
 
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Switch to the '''terminal'''.
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Switch to the terminal.
 
  
 
Type,
 
Type,
  
'''numbers '''''equal to inside square brackets''''' 4, 9, 16, 25, 36'''
+
'''numbers ''equal to inside square brackets'' 4, 9, 16, 25, 36''' and press '''Enter'''
  
'''for num in numbers '''''colon''''' '''Press '''Enter'''
+
 
 +
'''for num in numbers '''''colon'' Press '''Enter'''
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the dots
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight the three dots
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| You will notice that, the prompt changes to three dots.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| You will notice that, the '''prompt''' changes to three dots.  
  
And the cursor is not right after the three dots but, there are four spaces from the dots.
+
 
 +
And the cursor is not after the three dots but, there are four spaces from the three dots.
  
 
|-
 
|-
Line 227: Line 261:
  
 
Highlight the three dots
 
Highlight the three dots
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Please note that '''IPython''' automatically indents the block.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Please note that '''IPython''' automatically indents the '''block'''.  
  
The three dots tell you that you are inside a block.
+
 
 +
The three dots tell you that you are inside a '''block'''.
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki> Type
  
'''print(“sqrt of”, num, '''
+
'''print(“sqrt of”, num, ''''''“is”, num**0.5)'''
  
'''“is”, num**0.5)'''
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now type the rest of the '''for loop'''.
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now type the rest of the '''for loop''','''print'' '''inside parentheses inside quotes sqrt of comma '''''num '''''comma inside quotes is comma''''' num '''''raised to power of''''' 0.5'''
+
'''print ''inside parentheses inside quotes sqrt of comma ''num ''comma inside quotes is comma'' num ''asterick asterick which is raised to power of'' 0.5''' and press '''Enter'''
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now we have finished the statements in the block.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now we have finished the '''statements''' in the '''block'''.
 +
 
 +
 
 +
But still the '''interpreter''' is showing three dots.
 +
 
  
But still the interpreter is showing three dots, this means that you are still inside the block.  
+
This means that you are still inside the '''block'''.  
  
 
|-
 
|-
Line 251: Line 290:
  
 
press '''Enter''' twice
 
press '''Enter''' twice
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| To exit from the block press the '''Enter''' key twice without entering anything else.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| To exit from the '''block''', press '''Enter''' key twice without entering anything else.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Ipython Terminal]</nowiki>
  
Highlight output
+
Highlight the output
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| It printed the square root of each number in the list, which was executed in the '''for loop.'''
+
 
 +
%run -i sqrt_num_list.py
 +
 
 +
sqrt of 4 is 2.0
 +
 
 +
sqrt of 9 is 3.0
 +
 
 +
sqrt of 16 is 4.0
 +
 
 +
sqrt of 25 is 5.0
 +
 
 +
sqrt of 36 is 6.0
 +
 
 +
This is outside for-loop
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| It printed the square root of each number in the '''list''', which was executed in the '''for loop.'''
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Next we will see about '''range '''built-in function in Python.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Next we will see about '''range built-in function''' in '''Python'''.
  
 
|-
 
|-
Line 268: Line 321:
 
'''range()''' function
 
'''range()''' function
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Range() function generates a '''list''' of '''integers.'''
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| '''range()''' function generates a '''list''' of '''integers.'''
  
The syntax is: '''range '''''inside parentheses inside square brackets''''' start '''''comma close square brackets '''''stop '''''open square brackets comma''''' step '''''close square brackets''
+
The syntax is: '''range start ''comma'' stop ''comma'' step'''  
  
For example:  
+
|-
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Show Slide
  
'''range '''''inside parentheses''''' one '''''comma''''' twenty '''''comma''''' two '''– generates integers from
+
'''range()''' function
 +
 
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|
 +
 
 +
For example:
  
1 to 19 with step of 2
+
'''range ''inside parentheses'' one ''comma'' twenty ''comma'' two '''– generates integers from 1 to 19 with step of 2
  
'''range '''''inside parentheses''''' twenty '''– generates integers from 0 to 19
+
'''range ''inside parentheses'' twenty '''– generates integers from 0 to 19
  
 
|-
 
|-
Line 284: Line 342:
  
 
Highlight output
 
Highlight output
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the ending number that you specify will not be included in the list.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the ending number that you specify will not be included in the '''list'''.
  
 
|-
 
|-
Line 291: Line 349:
 
Exercise 2
 
Exercise 2
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Find out the cube of all the numbers from one to ten
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Find out the cube of all the numbers from one to ten.
  
Execute this in the '''Python''' interpreter.
+
Execute this in the '''Python interpreter'''.
 +
 
 +
|-
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Open a new terminal.
 +
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us now try to run the '''for loop''' in a '''Python terminal''' window.
 +
 
 +
Open a new '''terminal''' by  pressing '''Ctrl+Alt+T''' keys simultaneously.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Terminal]</nowiki>
 +
 +
Type
  
 
'''python'''
 
'''python'''
Line 304: Line 370:
 
press '''Enter'''
 
press '''Enter'''
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us now try to run the '''for''' loop in a Python terminal window.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 
+
Start the '''Python interpreter''' by issuing the '''command python '''in the new '''terminal''' and press '''Enter'''.
Start the '''Python''' '''interpreter''' by issuing the '''command''' '''python '''in a '''new terminal'''.
+
  
 
Type,
 
Type,
  
'''for i '''in range ''inside parentheses''''' one '''''comma '''''eleven '''''colon''''' '''press '''Enter'''
+
'''for i '''in range '''''inside parentheses'' one ''comma ''eleven ''colon'' and '''press '''Enter'''
  
 
|-
 
|-
Line 318: Line 383:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| We will see that this time it shows three dots, but the cursor is close to the dots.  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| We will see that this time it shows three dots, but the cursor is close to the dots.  
  
So we have to indent the block.
+
So we have to indent the '''block'''.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Python Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Python Terminal]</nowiki>
 +
Type
  
 
'''print(i, "cube is", i**3)'''
 
'''print(i, "cube is", i**3)'''
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| The '''Python''' interpreter does not indent the code automatically.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| The '''Python interpreter''' does not indent the code automatically.  
 +
 
  
So enter four spaces there and then type the following
+
So enter four '''spaces''' and then type the following.
  
'''print'' '''''inside parentheses''''' ''i '''''comma inside quotes''' ''cube is '''''comma''''' i '''''raised to''''' '''''power of''''' three'''
+
'''print ''inside parentheses'' i ''comma inside quotes ''cube is ''comma'' i ''raised to power of'' three''' press '''Enter'''.
  
 
|-
 
|-
Line 335: Line 402:
  
 
press '''Enter'''
 
press '''Enter'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now when we hit enter, we still see the three dots.  
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Now when we hit '''Enter''', we still see the three dots.  
  
To get out of the block, press '''Enter''' once again.
+
To get out of the '''block''', press '''Enter''' once again.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Python Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[Python Terminal]</nowiki>
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Okay! so the main thing we learnt here is -
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Okay!   So the main thing we learnt here is -
  
* how to use the '''Python''' '''interpreter''' and  
+
* how to use the '''Python interpreter''' and  
  
* the '''IPython''' interpreter to specify blocks.
+
* the '''IPython interpreter''' to specify '''blocks'''.
  
 
|-
 
|-
Line 357: Line 424:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki>
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us do it in our '''IPython''' interpreter for ease of use.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Let us do it in our '''IPython interpreter''' for ease of use.
  
The problem can be solved by just using the '''range()''' function.
+
The problem can be solved by just using the '''range() function'''.
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki>
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki> Type
  
for i in range(1, 51, 2):  
+
for i in range(1, 50, 2):  
  
 
     print(i)
 
     print(i)
Line 370: Line 437:
 
press '''Enter '''twice
 
press '''Enter '''twice
  
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| for''' i''' in '''range''' ''inside parentheses '''''one''' ''comma'' '''fifty one''' ''comma''''' two''''' colon ''
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"|  
 +
 
 +
Let us clear the '''terminal'''.
 +
 
 +
for''' i ''in range inside parentheses'' one ''comma'' fifty ''comma'' two ''colon '''
 +
 
 +
press '''Enter '''
 +
 
  
print'' inside parentheses'' '''i''' and press '''Enter '''twice
+
'''print'' inside parentheses'' i''' press '''Enter '''twice.
  
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki>
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| <nowiki>[IPython Terminal]</nowiki>
  
Highlight parameters in '''range '''function and highlight output
+
Highlight 1 and 50 in '''range '''function  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| The first '''parameter''' is the starting number of the sequence.
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| The first '''parameter''' is the starting number of the sequence.
  
Line 383: Line 457:
  
 
|-
 
|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight third parameter
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Highlight third parameter i.e. 2
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the '''sequence''' does not include the ending number.  
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Note that the '''sequence''' does not include the ending number.  
  
 
The third '''parameter''' is for stepping through the '''sequence'''.
 
The third '''parameter''' is for stepping through the '''sequence'''.
  
Here we gave '''two''' which means we are skipping every alternate element.
+
Here we gave '''two''' which means we are skipping every alternate '''element'''.
  
 
|-
 
|-
Line 399: Line 473:
 
In this tutorial, we learnt to,
 
In this tutorial, we learnt to,
  
# Create blocks in python using''' for'''
+
# Create '''blocks''' in '''python''' using''' for'''
# Indent the blocks of code
+
# Indent the '''blocks''' of code
# Iterate over a list using '''for''' loop
+
# Iterate over a list using '''for loop'''
# Use the '''range()''' function
+
# Use the '''range() function'''
  
 
|-
 
|-
Line 411: Line 485:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Here are some self assessment questions for you to solve
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Here are some self assessment questions for you to solve
  
# Indentation is not mandatory in '''Python'''
+
1. Indentation is not mandatory in '''Python'''
  
 
* True
 
* True
 
* False
 
* False
  
2. Write a '''for '''loop to print the product of all natural numbers from 1 to 20.
+
2. Write a '''for loop''' to print the product of all natural numbers from 1 to 20.
  
 
3. What will be the output of:
 
3. What will be the output of:
Line 429: Line 503:
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| And the answers,
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| And the answers,
  
# False, '''Indentation''' is essential in '''python'''.
+
1. False, '''Indentation''' is essential in '''python'''.
 
+
2.  
+
  
'''y '''''equal to''''' one'''
+
2. '''y '''''equal to''''' one'''
  
 
'''for x in range '''''inside parentheses''''' one '''''comma''''' twenty one''''' colon''''' '''
 
'''for x in range '''''inside parentheses''''' one '''''comma''''' twenty one''''' colon''''' '''
Line 441: Line 513:
 
'''print '''''inside parentheses '''''y'''
 
'''print '''''inside parentheses '''''y'''
  
3. '''range(1, 5)'''<nowiki> will produce a list of integers from 1 to 4 [1,2,3,4]</nowiki>
+
3. '''range(1, 5)'''<nowiki> will produce a list of integers from 1 to 4 i.e. [1,2,3,4]</nowiki>
  
 
|-
 
|-
Line 473: Line 545:
 
|-
 
|-
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Previous slide
 
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| Previous slide
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| This is _________ from IIT Bombay (or FOSSEE, if you wish) signing off.
+
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.088cm;padding-right:0.191cm;"| This is Trupti Kini from IIT Bombay signing off.
  
 
Thank you.
 
Thank you.
  
 
|}
 
|}

Latest revision as of 19:40, 8 January 2018

Title of script: Getting started with for loops

Author: Trupti, Thirumalesh H S

Keywords:Python, IPython, for loop, blocks, indent, iterate, loop

Visual Cue
Narration
Show Slide Hello Friends. Welcome to the tutorial on "Getting started with for loops".
Show Slide

Objectives

At the end of this tutorial, you will be able to,
  1. Use the for loop.
  2. Use range() function.
Show slide

System Specifications

To record this tutorial, I am using,
  • Ubuntu Linux 14.04 operating system
  • Python 3.4.3
  • IPython 5.1.0
Show Slide:

Pre-requisite

If not, see the relavant Python tutorials on http://spoken-tutorial.org

To practice this tutorial, you should know how to use lists.

If not, see the relevant Python tutorials on this website.

First let us see the syntax of for loop.
Show slide

Syntax: For

for <loop variable> in sequence:

   <statement 1>
   <statement 2> 
   ...
   <statement n>

Highlight according to narration

for statement iterates over the members of a sequence in order, executing the block each time.


Here the loop variable takes the value of the item inside the sequence on each iteration.


For each item, the loop body is executed.

We will see an example of for loop and how to execute it.
[Terminal]

ipython3

Let us first open the Terminal by pressing Ctrl+Alt+T keys simultaneously.


Now, type ipython3 and press Enter.

[IPython console]

%pylab and press Enter.

Let us initialise the pylab package.

Type %pylab and press Enter.

Open your text editor. Open your text editor.
Highlight according to narration Let us write a for loop. Type the code as shown here:
numbers = [4, 9, 16, 25, 36]

for num in numbers:

   print(“sqrt of”, num, “is”, num**0.5)

print("This is outside for-loop")

Here the loop variable iterates over a list of numbers and finds the square root of each number.


The numbers are: 4, 9, 16, 25, and 36.


Note that here we used two variables,

  • numbers - which is a list of numbers
  • num - which is the element of list under consideration, in each cycle of the for loop.

The variable names can be any of your choice.

Highlight the line print(“sqrt of”, num, “is”, num**0.5) Note that a colon after the for statement indicates the starting of loop body.


Every statement in loop starts with 4 spaces.

Highlight the line print(“sqrt of”, num, “is”, num**0.5) It means that, the line is a block of code in for loop.


In this example, it is only a single statement in the block.

Highlight the fifth line -

print("This is outside for-loop")

Note that the line print("This is outside for-loop") is not indented.


It means that it is not a part of the for loop.


And the lines after that don't fall in the scope of the for loop.

Highlight indentation Thus each block is separated by the indentation level.


This marks the importance of white-spaces in Python.

Save the file as sqrt_num_list.py Save the file as sqrt_num_list.py in the home directory.
switch back to your terminal. Clear the terminal Now switch back to your terminal.


Let us clear the terminal.

[Ipython Terminal]

Save & run script

Highlight the output

%run -i sqrt_num_list.py

sqrt of 4 is 2.0

sqrt of 9 is 3.0

sqrt of 16 is 4.0

sqrt of 25 is 5.0

sqrt of 36 is 6.0

This is outside for-loop

Run the script using the run command as-

percent run minus i filename and press Enter.

Highlight the output

%run -i sqrt_num_list.py

sqrt of 4 is 2.0

sqrt of 9 is 3.0

sqrt of 16 is 4.0

sqrt of 25 is 5.0

sqrt of 36 is 6.0

This is outside for-loop

We get the square root of the given numbers executed by the for loop.


This is the print statement output executed after the for loop.

Show Slide

Exercise 1

  • Use the same example we used in sqrt_num_list.py
  • Type each line of the code in the IPython interpreter prompt.
  • Skip the line: print("This is outside for-loop")
[Ipython Terminal]

Type

numbers = [4, 9, 16, 25, 36]

for num in numbers:

Press Enter

Switch to the terminal.


Type,

numbers equal to inside square brackets 4, 9, 16, 25, 36 and press Enter


for num in numbers colon Press Enter

Highlight the three dots You will notice that, the prompt changes to three dots.


And the cursor is not after the three dots but, there are four spaces from the three dots.

[Ipython Terminal]

Highlight the three dots

Please note that IPython automatically indents the block.


The three dots tell you that you are inside a block.

[Ipython Terminal] Type

'print(“sqrt of”, num, '“is”, num**0.5)

Now type the rest of the for loop.

print inside parentheses inside quotes sqrt of comma num comma inside quotes is comma num asterick asterick which is raised to power of 0.5 and press Enter

[Ipython Terminal] Now we have finished the statements in the block.


But still the interpreter is showing three dots.


This means that you are still inside the block.

[Ipython Terminal]

press Enter twice

To exit from the block, press Enter key twice without entering anything else.
[Ipython Terminal]

Highlight the output

%run -i sqrt_num_list.py

sqrt of 4 is 2.0

sqrt of 9 is 3.0

sqrt of 16 is 4.0

sqrt of 25 is 5.0

sqrt of 36 is 6.0

This is outside for-loop

It printed the square root of each number in the list, which was executed in the for loop.
Next we will see about range built-in function in Python.
Show Slide

range() function

range() function generates a list of integers.

The syntax is: range start comma stop comma step

Show Slide

range() function

For example:

range inside parentheses one comma twenty comma two – generates integers from 1 to 19 with step of 2

range inside parentheses twenty – generates integers from 0 to 19

[Ipython Terminal]

Highlight output

Note that the ending number that you specify will not be included in the list.
Show Slide

Exercise 2

Find out the cube of all the numbers from one to ten.

Execute this in the Python interpreter.

Open a new terminal. Let us now try to run the for loop in a Python terminal window.

Open a new terminal by pressing Ctrl+Alt+T keys simultaneously.

[Terminal]

Type

python

for i in range(1, 11):

press Enter

Start the Python interpreter by issuing the command python in the new terminal and press Enter.

Type,

for i in range inside parentheses one comma eleven colon and press Enter

[Python Terminal]

Highlight the cursor

We will see that this time it shows three dots, but the cursor is close to the dots.

So we have to indent the block.

[Python Terminal]

Type

print(i, "cube is", i**3)

The Python interpreter does not indent the code automatically.


So enter four spaces and then type the following.

print inside parentheses i comma inside quotes cube is comma i raised to power of three press Enter.

[Python Terminal]

press Enter

Now when we hit Enter, we still see the three dots.

To get out of the block, press Enter once again.

[Python Terminal] Okay! So the main thing we learnt here is -
  • how to use the Python interpreter and
  • the IPython interpreter to specify blocks.
Show Slide

Exercise 3

Print all the odd numbers from 1 to 50.
[IPython Terminal] Let us do it in our IPython interpreter for ease of use.

The problem can be solved by just using the range() function.

[IPython Terminal] Type

for i in range(1, 50, 2):

   print(i)

press Enter twice

Let us clear the terminal.

for i in range inside parentheses one comma fifty comma two colon

press Enter


print inside parentheses i press Enter twice.

[IPython Terminal]

Highlight 1 and 50 in range function

The first parameter is the starting number of the sequence.

The second parameter is the end of the range.

Highlight third parameter i.e. 2 Note that the sequence does not include the ending number.

The third parameter is for stepping through the sequence.

Here we gave two which means we are skipping every alternate element.

Show Slide

Summary

This brings us to the end of the tutorial.

In this tutorial, we learnt to,

  1. Create blocks in python using for
  2. Indent the blocks of code
  3. Iterate over a list using for loop
  4. Use the range() function
Show Slide

Assignment

Here are some self assessment questions for you to solve

1. Indentation is not mandatory in Python

  • True
  • False

2. Write a for loop to print the product of all natural numbers from 1 to 20.

3. What will be the output of:

range(1, 5)

Show Slide

Solution of self assessment questions on slide

And the answers,

1. False, Indentation is essential in python.

2. y equal to one

for x in range inside parentheses one comma twenty one colon

y into equal to x

print inside parentheses y

3. range(1, 5) will produce a list of integers from 1 to 4 i.e. [1,2,3,4]

Show Slide

Forum

Please post your timed queries in this forum.
Show Slide

Fossee Forum

Please post your general queries on Python in this forum.
Show Slide

Textbook Companion

FOSSEE team coordinates the TBC project.
Show Slide

Acknowledgment

http://spoken-tutorial.org

Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this website.

Previous slide This is Trupti Kini from IIT Bombay signing off.

Thank you.

Contributors and Content Editors

Nancyvarkey, Nirmala Venkat, Trupti