20 In this tutorial we shall be looking at Functions in Python. We already |
20 In this tutorial we shall be looking at Functions in Python. We already |
21 have looked at the basics of functions in the tutorial on solving |
21 have looked at the basics of functions in the tutorial on solving |
22 equations. We shall first review these basics. Then we shall move on to |
22 equations. We shall first review these basics. Then we shall move on to |
23 other details such as doc-strings, default arguments and keyword |
23 other details such as doc-strings, default arguments and keyword |
24 arguments. |
24 arguments. |
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25 |
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26 First let's start IPython by typing ipython in the terminal. |
25 |
27 |
26 Let's write a simple function that prints a Hello message, after |
28 Let's write a simple function that prints a Hello message, upon |
27 accepting a name. |
29 accepting a name. |
28 |
30 |
29 def welcome(name): |
31 def welcome(name): |
30 print "Hello", name |
32 print "Hello", name |
31 |
33 |
32 You would recall that def is a keyword that indicates a function |
34 You would recall that def is a keyword that indicates the function |
33 definition. 'welcome' is the name of the function and 'name' is |
35 definition. 'welcome' is the name of the function and 'name' is |
34 the lone argument to the function. Note that the function is |
36 the lone argument to the function. Note that the function is |
35 defined within an indented block, similar to any other block. Our |
37 defined within an indented block, just like to any other block. Our |
36 function welcome just has one line in it's definition. |
38 function welcome just has one line in it's definition. |
37 |
39 |
38 We can call our function, as follows - |
40 We can call our function, as follows - |
39 welcome("World") |
41 welcome("World") |
40 |
42 |
53 print "Hello", name |
55 print "Hello", name |
54 |
56 |
55 Notice that the doc string uses triple quotes. If the doc-string |
57 Notice that the doc string uses triple quotes. If the doc-string |
56 exceeds one line, we can use new line characters in it. |
58 exceeds one line, we can use new line characters in it. |
57 Also, as expected the doc-string is indented as is required |
59 Also, as expected the doc-string is indented as is required |
58 for anything within a block. |
60 for anything within a block. Now that we have written the |
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61 documentation, how do we access it? IPython provides the question |
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62 mark feature that we have seen in the previous tutorials. welcome? |
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63 will display the docstring that we have just written. |
59 |
64 |
60 We shall now look at default arguments. |
65 We shall now look at default arguments. |
61 [show slide with examples of functions with default arguments] |
66 [show slide with examples of functions with default arguments] |
62 The split function has been used in two different ways in the |
67 The split function has been used in two different ways in the |
63 given example - one for splitting on spaces and the other for |
68 given example - one for splitting on spaces and the other for |