Python/C2/Getting-started-with-ipython/English-timed
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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 functions. 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 toabs 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 | Let's 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 let's try it for decimal numbers; let's 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 example 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! |