Difference between revisions of "Python/C2/Getting-started-with-ipython/English-timed"
From Script | Spoken-Tutorial
| Line 12: | Line 12: | ||
# invoke the ipython interpreter . | # invoke the ipython interpreter . | ||
| − | # quit the | + | # quit the ipython interpreter. |
| − | # navigate the | + | # navigate the ipython session history. |
# use tab-completion for writing ipython functions. | # use tab-completion for writing ipython functions. | ||
# look-up documentation of functions. | # look-up documentation of functions. | ||
Revision as of 15:01, 6 March 2013
| Timing | Narration |
|---|---|
| 0:00 | Hello Friends and Welcome to the tutorial on "getting started with ipython". |
| 0:07 | At the end of this tutorial, you will be able to,
|
| 0:27 | IPython is an enhanced Python interpreter that provides features like tab-completion, easier access to help and many other functionalities. |
| 0:37 | Let us first see how to start the ipython interpreter. |
| 0:41 | First open the terminal, type ipython in the terminal and hit enter. |
| 0:51 | After getting some information about the version of Python installed and some help commands, we get a prompt with In[1]:. |
| 0:59 | But, if you get an error saying 'ipython is not installed' then refer to the tutorial on how to install the packages. |
| 1:09 | Now, lets see how we can quit the ipython interpreter, press Ctrl-D. |
| 1:17 | 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. |
| 1:28 | Press y. |
| 1:32 | Now since we have quit the interpretor, let us start it again by typing ipython |
| 1:42 | And now let's see, how to use the interpreter. |
| 1:46 | Start with the simplest thing, addition. |
| 1:48 | type 1+2 at the prompt. |
| 1:55 | IPython promptly gives back the output as 3. |
| 1:59 | Notice that the output is displayed with an Out[1] indication. |
| 2:05 | Now, Let us now try few more operations such as, 5 minus 3, 7 minus 4, 6 into 5. |
| 2:23 | Now let's see how the ipython remembers the history of commands. |
| 2:29 | For example ,print 1+2. |
| 2:33 | Instead of typing the whole thing,use the up arrow key to go back to the command 1+2which 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. |
| 2:55 | We have changed the line to print 1+2, now press enter. |
| 3:02 | The interpreter prints the result as 3. |
| 3:06 | Please note that the indication Out square brackets is not shown here. |
| 3:11 | Now let us do print 10 into 2. |
| 3:16 | We use the up arrow key to navigate to the previous command 1+2. |
| 3:22 | Now change 1 plus 2 to 10 into 2 and press enter. |
| 3:34 | Till now, we saw how to invoke the ipython interpreter,quit the ipython and navigate through previous commands in ipython. |
| 3:42 | Now, let's see, what is tab-completion?. |
| 3:47 | let's take an example, suppose we want to use the function round. |
| 3:52 | For this we just type ro at the prompt and press the tab key. |
| 4.00 | As you can see on the terminal, IPython completes the command ro into round, This feature of ipython is called the tab-completion. |
| 4:08 | Let's see some more possibilities of tab completion just type r and then press the tab. |
| 4:19 | 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. |
| 4:31 | Now let's try out an exercise. |
| 4:33 | Pause the video,solve the problem and resume the video. |
| 4:39 | 1. find out the commands starting with "ab"? |
| 4:44 | 2. list out the commands starting with "a"? |
| 4:54 | ab tab completes toabs and a tab gives us a list of all the commands starting with a. |
| 5:07 | Now, let's see what the functions abs is used for. |
| 5:12 | We will use the help features of ipython to find out this. |
| 5:15 | To see the documentation of a function, type the function name followed by a question mark and hit enter. |
| 5:24 | Ipython interpreter will show the documentation for the function. |
| 5:27 | Let us see the documentation of the function abs, type abs? and press enter |
| 5:38 | As the documentation says, abs accepts a number as an input and returns it's absolute value. |
| 5:46 | lets see few examples, |
| 5:49 | Type abs(-19) and abs(19) on the interpreter. |
| 6:04 | We get 19, as expected, in both the cases. |
| 6:08 | Now lets try it for decimal numbers; lets try abs(-10.5), we got 10.5 as the result. |
| 6:24 | Pause the video here, try out the following exercise and resume the video. |
| 6:31 | Look-up the documentation of round and see how to use it. |
| 6:39 | And you can look up the documentation of the function round by typing round question mark in the ipython interpreter. |
| 6:47 | If you notice, there are extra square brackets around ndigits. |
| 6:53 | This means that ndigits is optional and 0 is the default value. |
| 6:58 | Optional parameters are shown in square brackets in Python documentation. |
| 7:03 | A function round, rounds a number to a given precision. |
| 7:09 | Pause the video here, try out the following exercise and resume the video. |
| 7:16 | let us now try few more examples with the function round. |
| 7:21 | 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) |
| 7:43 | Now, we got 2.0, 2.5 and 2.48, which are what we expect. |
| 7:54 | 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. |
| 8:12 | let us make a typing error deliberately, type round(2.484 and hit enter, without closing the parenthesis. |
| 8:25 | We get a prompt with dots . |
| 8:28 | This prompt is the continuation prompt of ipython. |
| 8:32 | It appears when, the previous line is incomplete. |
| 8:36 | now complete the command of the same examples with close parenthesis and press enter. |
| 8:49 | We got the expected output that is 2.0 |
| 8:51 | 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. |
| 9:15 | Pause the video here, try out the following exercise and resume the video. |
| 9:22 | 1.type round(2.484, and press enter. and then cancel the command using Ctrl-C. |
| 9:45 | 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! |
