View source for Python/C2/Getting-started-with-ipython/English-timed

{| border=1
|'''Time'''
|'''Narration'''

|-
| 00:00
| Hello friends and welcome to the tutorial on '''Getting started with ipython'''.

|-
| 00:07
| At the end of this tutorial, you will be able to:
# invoke the '''ipython interpreter''' .
# quit the ipython interpreter.
# navigate the ipython session '''history'''.
# use tab-completion for writing '''ipython function'''s.
# look-up documentation of functions.
# interrupt incomplete or incorrect commands.

|-
|  00:27
| '''iPython''' is an enhanced '''Python interpreter''' that provides features like tab-completion, easier access to '''help''' and many other functionalities.

|-
| 00:37
|Let us first see how to start the  '''ipython  interpreter'''.

|-
| 00:41
| First, open the terminal. Type: "ipython" in the terminal and hit '''Enter'''.

|-
| 00:51
| After getting some information about the version of Python installed and some help commands, we get a prompt with '''In[1]:'''.

|-
| 00:59
|But, if you get an error saying 'ipython is not installed' then refer to the tutorial on how to install the packages.

|-
| 01:09
| Now, let's see how we can quit the 'ipython interpreter'. Press '''Ctrl, D'''.

|-
| 01:17
| A prompt will appear to confirm whether you really want to exit; type 'y' to say 'yes' and quit 'ipython' and 'n' to say 'no' if you don't want to quit the ipython. 

|-
| 01:28
| Press 'y'.

|-
| 01:32
| Now, since we have quit the interpreter, let us start it again by typing "ipython".

|-
| 01:42
| And now let's see, how to use the interpreter.

|-
| 01:46
|Start with the simplest thing, addition.

|-
| 01:48
|type: '''1+2'''at the prompt. 

|-
| 01:55
|'''iPython''' promptly gives back the output as ''3''. 

|-
| 01:59
|Notice that the output is displayed with an '''Out[1]''' indication.

|-
| 02:05
| Now, let us try few more operations such as- '''5 minus 3, 7 minus 4, 6 into 5'''.

|-
| 02:23
| Now, let's see how the ipython remembers the '''history''' of commands. 

|-
| 02:29
|For example,'''print 1+2'''.

|-
| 02:33
|Instead of typing the whole thing, use the '''up-arrow key''' to go back to the command ''1+2'' which we did before. Now use the left-arrow key to navigate to the beginning of the line and type the word "print" and press space.

|-
| 02:55
| We have changed the line to print 1+2, now press '''Enter'''. 

|-
| 03:02
|The interpreter prints the result as ''3''.

|-
| 03:06
| Please note that the indication '''Out''' square brackets is not shown here.

|-
| 03:11
| Now, let us do print'' 10 into 2''. 

|-
| 03:16
|We use the up-arrow key to navigate to the previous command ''1+2''.

|-
|03:22
| Now, change ''1 plus 2 to 10 into 2'' and press '''Enter'''.

|-
| 03:34
| Till now, we saw how to invoke the 'ipython interpreter', quit the ipython and navigate through previous commands in ipython. 

|-
| 03:42
|Now, let's see, what is tab-completion?. 

|-
| 03:47
|Let's take an example. Suppose, we want to use the function '''round'''.

|-
|03:52
| For this, we just type '''ro''' at the prompt and press the '''tab''' key.

|-
| 04:00
| As you can see on the terminal, IPython completes the command '''ro''' into '''round'''. This feature of ipython is called the '''tab-completion'''.

|-
| 04:08
| Let's see some more possibilities of tab completion just type'' r'' and then press the''' tab'''.

|-
| 04:19
| As you can see that IPython does not complete the command. This is because, there are many possibilities of ''r'' therefore it just lists out all the possible completions of 'r'.

|-
| 04:31
| Now, let's try out an exercise.

|-
| 04:33
| Pause the video, solve the problem and resume the video.

|-
| 04:39
| 1. find out the commands starting with "ab"?

|-
| 04:44
| 2. list out the commands starting with "a"?

|-
| 04:54
|'' ab'' tab completes to''abs'' and ''a tab gives us a list of all the commands starting with a.

|-
| 05:07
| Now, let's see what the functions abs is used for.

|-
| 05:12
| We will use the help features of ipython to find out this.

|-
|05:15
| To see the documentation of a function, type the function name followed by a question mark and hit enter.

|-
| 05:24
| Ipython interpreter will show the documentation for the function.

|-
| 05:27
| Let us see the documentation of the function abs, type abs? and press enter

|-
| 05:38
| As the documentation says, ''abs'' accepts a number as an input and returns it's absolute value.

|-
| 05:46
|lets see few examples,

|-
| 05:49
|Type ''abs(-19)'' and'' abs(19)'' on the interpreter.

|-
| 06:04
|We get ''19'', as expected, in both the cases.

|-
| 06:08
| Now lets try it for decimal numbers; lets try'' abs(-10.5)'', we got ''10.5'' as the result.

|-
| 06:24
| Pause the video here, try out the following exercise and resume the video.

|-
| 06:31
|Look-up the documentation of ''round'' and see how to use it.

|-
| 06:39
| And you can look up the documentation of the function round by typing round ''question mark'' in the ipython interpreter.

|-
| 06:47
| If you notice, there are extra square brackets around ''ndigits''.

|-
| 06:53
| This means that ''ndigits'' is optional and 0 is the default value.

|-
| 06:58
| Optional parameters are shown in square brackets in Python documentation.

|-
| 07:03
|A function ''round'', rounds a number to a given precision.

|-
| 07:09
| Pause the video here, try out the following exercise and resume the video.

|-
| 07:16
| let us now try few more examples with the function round.

|-
| 07:21
| Check the output of ''round(2.48) round(2.48, 1) round(2.48, 2) round(2.484) round(2.484, 1) round(2.484, 2)''

|-
| 07:43
| Now, we got'' 2.0, 2.5 and 2.48'', which are what we expect.

|-
| 07:54
| Let's now see how to correct typing errors, which we often make while typing at the terminal.

|-
| 08:01
| As already shown, if we haven't hit the enter key already, we could navigate using the arrow keys and make deletions using delete or backspace key and correct the errors.

|-
| 08:12
|let us make a typing error deliberately, type round(2.484 and hit enter, without closing the parenthesis.

|-
| 08:25
| We get a prompt with ''dots'' . 

|-
| 08:28
|This prompt is the continuation prompt of ''ipython''.

|-
| 08:32
| It appears when, the previous line is incomplete.

|-
| 08:36
| now complete the command of the same examples with close parenthesis and press enter. 

|-
|08:49
|We got the expected output that is ''2.0''

|-
| 08:51
| In other instances, if we commit a typing error with a longer and more complex expression and end up with the continuation prompt, we can type Ctrl-C to interrupt the command and get back to the  ipython input prompt.

|-
| 09:15
| Pause the video here, try out the following exercise and resume the video.

|-
| 09:22
| 1.type round(2.484, and press enter. and then cancel the command using ''Ctrl-C''.

|-
| 09:45
| 2. type the command, round(2.484, 2)

|-
| 10:09
| Now, let us revise quickly what we learn't today. In this tutorial,we learn't to,

|-
| 10:15
| 1. Invoke the ipython  interpreter by typing ipython.

|-
| 10:20
| 2. To quit the ipython  interpreter by using ctrl-d.

|-
| 10:22
| 3. To navigate in the history of  ipython  by using the arrow keys.

|-
| 10:28
| 4. What is tab-completion 

|-
| 10:30 
| 5. To see the documentation of functions using question mark.

|-
| 10:34
| 6.  To Interrupt using ctrl-c when we make an error.

|-
| 10:39
| Here are some self assessment questions for you to solve

|-
| 10:44
|  '''ipython is a programming language similar to Python.

|-
| 10:50
|''' True or False''

|-
| 10:53 
| Second one. Which key combination quits ipython ? '' Ctrl + C Ctrl + D Alt + C Alt + D''

|-
| 11:03
| And The last one. Which character is used at the end of a command, in Ipython to display the documentation. under score'' (_) ''question mark'' (?)'' exclamation mark'' (!)'' ampersand ''(&)''

|-
| 11:16
| And the answers are,

|-
| 11:18
| Ipython is not a programming language, it is just an interpreter.

|-
| 11:23
| Second one is We use ''Ctrl D'' to quit Ipython interpreter.

|-
| 11:27
| The final one is We use ? at the end of the function name to display its documentation.

|-
| 11:36
| So we hope you have enjoyed this tutorial and found it useful. 

|-
|11:39
|Thank you!

|}