Python-3.4.3/C2/Getting-started-with-IPython/English

Python/C2/Getting-started-with-IPython/English

Title of script: Getting started with IPython

Author: Puneeth, Jovina, Thirumalesh H S

Keywords: Python, IPython

Visual Cue	Narration
Show Slide	Hello Friends. Welcome to the tutorial on "getting started with IPython".
Show Slide Objectives	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 within IPython. look-up documentation in IPython. interrupt incomplete or incorrect commands.
Show Slide System Specifications	To record this tutorial, I am using Ubuntu Linux 14.04 operating system Python 3.5.2 IPython 5.1.0
Show Slide: What is IPython	What is IPython? IPython is an enhanced interactive Python interpreter. It provides features like tab-completion, and easier access to help.
[Terminal] Type ipython >> press Enter	Let us first see how to start the IPython interpreter. First open the terminal by pressing Ctrl+Alt+T keys simultaneously on the keyboard. Type ipython3 at the prompt and press Enter. If IPython is not installed, please refer to the instructions sheet.
[IPython Terminal] Point to the version information with mouse.	If IPython is installed, the IPython interpreter is loaded by running the ipython command in the terminal The versions of Python and IPython that are installed, are shown on the terminal.
[IPython Terminal] Point to In[1]: prompt with mouse	Some additional helpful information is printed by IPython. After this, we get a prompt with In[1]:
[IPython Terminal] Type Ctrl+D	Now, Let us see how we can quit the IPython interpreter. Press Ctrl+D keys.
]IPython Terminal]	A prompt will appear to confirm if we really want to exit. Type y for yes and quit IPython. Note that y is given in square brackets so it is default. We could also press Enter and it will exit. Else type n for no if you don't want to quit IPython.
[IPython Terminal] Type y >> press Enter.	Let us type y. We have quit IPython interpreter and are back at the terminal prompt.
[Terminal] Type ipython >> press Enter	Let us start it again. Type ipython3 in the terminal and press Enter.
[IPython Terminal]	Now, Let us learn how to use the interpreter. Let us start with the simplest operation - addition.
[IPython Terminal] 1+2 Point at the Out[1] prompt	Type 1 plus 2 at the IPython prompt and press Enter. We press Enter to execute the python command. Please do so after typing every command. IPython promptly displays the output as 3. Notice that the output is shown with an Out square brackets 1 indication.
[IPython Terminal] 5 – 3 7 * 4	Let us now try a few more operations such as, 5 minus 3, 7 multiplied by 4, Each time we press Enter and see the output on the IPython console window.
IPython Terminal	Let us see how we can navigate to previous commands in IPython.
[IPython Terminal]	For example, say, we want to execute print (1 plus 2). Instead of typing the whole command, we can recall the command 1 plus 2 we typed earlier.
[IPython Terminal] Use the up arrow key to go back to the command 1+2.	Use the up arrow key to go back to the command 1 plus 2.
[IPython Terminal] Use left arrow to navigate to start of line	Now use the left-arrow key to navigate to the beginning of the line.
[IPython Terminal] Type print (>> press space) and press Enter.	Type the word print (and press space key) on the keyboard. We have changed the command to print (1 plus 2). Now press Enter.
[IPython Terminal] Highlight the result line. Point at the Output	The interpreter prints the result as 3. Notice that this time, the indication Out square brackets is not displayed.
[IPython Terminal] Press up-arrow key	Now let us execute print 10 multiplied by 2. We use the up arrow key to navigate to the previous command print (1 plus 2).
[IPython Terminal] Change print (1+2) to print (10*2)	Now replace 1 plus 2 with 10 multiplied by 2 and press Enter. As with any programming language, asterix is used for multiplication operation.
[IPython Terminal] Highlight output	Observe the output on the console. <<PAUSE>>
[IPython Terminal]	Now, Let us see, what is tab-completion. Let us consider an example.
[IPython Terminal] pri<tab>	Suppose we want to use the function print. For this we just type pri at the prompt and press the tab key.
[IPython Terminal]	As you can see on the console that IPython has autocompleted the command pri to print. This feature of IPython is called the tab-completion.
[IPython Terminal] p<tab>	Let us see some more possibilities of tab completion. Just type p and then press the tab.
[IPython Terminal]	In this case, we see that IPython does not complete the command. This is because, there are more than one command beginning with p. Therefore, it just lists out all the possible tab-completion of p.
Show Slide: Exercise 1	Now Let us try out an exercise. Pause the video, solve the problem and resume the video. find out the commands starting with "ab". list out the commands starting with "a".
[IPython Terminal] ab<tab> a<tab>	ab tab autocompletes to abs. a<tab> displays a list of all the commands starting with a.
[IPython Terminal]	Now, Let us see what the function abs is used for. We will use the help feature of IPython to find out this.
[IPython Terminal]	To see the documentation of a function, type the function name followed by a question mark. IPython interpreter will show the documentation for the function. Let us see the documentation of the function abs.
[IPython Terminal] Type abs? >> press Enter	Type abs? and press Enter. From the displayed information, it says abs accepts a number as input and returns it's absolute value.
[Ipython Terminal] abs(-19) abs(19)	Let us see few examples, On the console, type abs(-19) and then abs(19). We get 19, as expected, in both the cases.
[Ipython Terminal] abs(-10.5)	Now Let us try it for decimal numbers. Let us try abs(-10.5). We get 10.5 as the result.
Show Slide Exercise 2 round?	Pause the video here. Try out the following exercise and resume the video. Look-up the documentation of round and see how to use it.
[IPython Terminal] Type round? Highlight the definition of round	Switch to the console for the solution. You can look up the documentation of the function round by typing round question mark. It says here that the function round, rounds a number to a given precision.
[IPython Terminal] Highlight the syntax of ndigits	ndigits is the precision value for round function. Notice, there are extra square brackets around ndigits. This means that ndigits is optional and 0 is the default value. Optional parameters are shown in square brackets in Python documentation.
Show Slide Exercise 3	Pause the video here. Try out the following exercise and resume the video. Check the output of round(2.48) round(2.48, 1)round(2.484) round(2.484, 2)
Show Slide Solution 3	We get 2.0 2.5 2.0 2.48 which are what we expect.
[IPython Terminal] round(2.484 Press Enter	Let us now see how to correct typing errors, which we could make while typing on the console. Let us make a typing error deliberately. Type round(2.484 and press Enter, without closing the parenthesis.
[IPython Terminal] Point at the prompt with three dots	We get a prompt with dots. This prompt is the continuation prompt of IPython. It appears when, the previous line is incomplete.
Type ) >> press Enter	Now complete the command with close parenthesis and press Enter. We get the expected output, that is 2.0
[IPython Terminal] round(1a >> press Enter press Ctrl+C	What if we type an incorrect command and end up with the continuation prompt? In such case, we can press Ctrl+C keys, to interrupt the command and get back to the IPython prompt. E.g, round takes only numbers as input. Type round(1a Do not close the paranthesis and press Enter. We gave alpha-numeric value '1a' as input. Press Ctrl+C to iterrupt the execution.
Show Slide Exercise 4	Pause the video here. Try out the following exercise and resume the video. Type round(2.484, and press Enter. Then cancel the command using Ctrl+C. Type the command, round(2.484, 2)
[IPython Terminal] round(2.484 Ctrl+C round(2.484, 2)	The output on your console should look like this.
Show Slide Summary	This brings us to the end of this tutorial. In this tutorial,we have learnt to, invoke the IPython interpreter by typing ipython in the terminal. quit the IPython interpreter by using Ctrl+D. navigate IPython session history by using the arrow keys. use the tab-completion to work faster. see the documentation of functions using question mark. interrupt commands using Ctrl+C when we make an error.
Show Slide Assignment	Here are some self assessment questions for you to solve IPython is a programming language similar to Python.True or False Which key combination quits IPython? Ctrl + C Ctrl + D Alt + C Alt + D 3. Which character is used at the end of a command, in IPython to display the documentation? under score (_) question mark (?) exclamation mark (!) ampersand (&)
Show Slide Solutions	And the answers are- False. IPython is not a new programming language. It is just an enhanced interactive Python interpreter. We use Ctrl + D to quit IPython interpreter. We use ? at the end of the command to display its documentation.
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Show Slide Acknowledgement	The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India
Show Slide Thank You	This is __________ from IIT Bombay signing off. Thanks for watching

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