PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Advanced Features of Functions'''. |- | 00:0..."

2019-06-04T12:31:27Z

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{| border=1
| <center>'''Time'''</center>
| <center>'''Narration'''</center>

|-
| 00:01
| Welcome to the spoken tutorial on '''Advanced Features of Functions'''.

|-
| 00:07
| In this tutorial, we will learn to- Assign''' default values''' to '''arguments''', when defining '''functions'''

|-
| 00:15
| Define and call '''functions''' with '''keyword arguments'''

|-
| 00:20
| Define and call '''functions''' with '''arbitrary arguments'''

|-
| 00:25
| Learn some of the '''built-in functions''' available in '''Python standard library'''.

|-
| 00:31
| To record this tutorial, I am using

'''Ubuntu Linux 16.04''' operating system

|-
| 00:38
| '''Python 3.4.3''' and '''IPython 5.1.0'''

|-
| 00:45
| To practise this tutorial, you should know how to

run basic '''Python '''commands on the '''IPython console'''

use''' functions.'''

|-
| 00:55
| If not, see the relevant '''Python '''tutorials on this website.

|-
| 01:00
| First let us see about default '''arguments''' in '''Python'''.

|-
| 01:05
| '''Function arguments''' can have default values in '''Python'''.

|-
| 01:10
| When we call a '''function''' without a value for an '''argument''', its default value is used if available

|-
| 01:18
| Otherwise it will give error.

|-
| 01:21
| Let us start '''ipython'''.

Open the '''terminal.'''

|-
| 01:26
| Type '''ipython3 '''and press '''Enter.'''

|-
| 01:30
| From here onwards, remember to press the '''Enter''' key after typing every '''command''' on the '''terminal'''.

|-
| 01:37
| Let us define a '''function Welcome'''.

|-
| 01:40
| Type the code as shown.

|-
| 01:44
| Here, '''welcome''' is the '''function''' name

'''greet''' is the '''argument''' with no default values and the '''name argument''' has a default value '''World'''.

|-
| 01:55
| In a '''function,''' all the '''arguments''' with default values should come after non-default '''arguments'''.

|-
| 02:03
| Let us first call the '''function welcome''' with two '''arguments'''

|-
| 02:08
| Type, '''welcome''''' inside brackets inside double quotes '''''Hi '''''comma inside double quotes''''' Chandru'''

|-
| 02:17
| We get the expected welcome message,''' Hi Chandru. '''

|-
| 02:21
| Now let us call the '''function''' with one '''argument''' only.

|-
| 02:25
| Type, '''welcome '''''inside brackets inside double quotes '''''Hello '''

|-
| 02:31
| We get the output as '''Hello World'''.

|-
| 02:35
| Here, '''“Hello”''' is passed to the parameter '''greet '''and

|-
| 02:39
| '''“World” '''is the default value of the '''name''' parameter.

|-
| 02:44
| Let us add another parameter '''age''' with default value as 23 as shown.

|-
| 02:51
| Now type, '''welcome '''''inside brackets inside double quotes '''''Hello'''

|-
| 02:58
| Here, '''welcome function''' still works since we have provided default value for '''age'''.

|-
| 03:06
| Default values allow us to add new '''parameters''' to an existing '''function'''.

|-
| 03:12
| It will not break the existing usage of the '''function'''.

|-
| 03:16
| Pause the video.

Try this exercise and then resume the video.

|-
| 03:22
| Redefine the '''function welcome''', by interchanging its '''arguments'''.

|-
| 03:27
| Place the '''name argument''' with its default value of "'''World'''" before the '''greet argument'''.

|-
| 03:34
| Switch to the '''terminal''' for the solution.

|-
| 03:38
| Type as shown.

|-
| 03:42
| We get an error that reads '''SyntaxError: non-default argument follows default argument'''.

|-
| 03:50
| When defining a '''function''' all the '''arguments''' with default values should come at the end.

|-
| 03:57
| Pause the video.

Try this exercise and then resume the video.

|-
| 04:03
| Redefine the '''function welcome''' with a default value of "'''Hello'''" to the '''greet argument'''.

|-
| 04:10
| Then, call the '''function''' without any '''arguments'''.

|-
| 04:14
| Switch to the '''terminal''' for the solution.

|-
| 04:18
| Type as shown.

|-
| 04:21
| Then type, '''welcome '''''open and close brackets''

|-
| 04:26
| As we can see, we get the output as''' Hello World.'''

|-
| 04:31
| Default values of both '''parameters''' are used since '''function''' is called without passing any value.

|-
| 04:39
| Next let us see what are '''keyword arguments.'''

|-
| 04:43
| We no need to remember the order of '''arguments '''while calling '''functions''' by passing''' keyword arguments'''.

|-
| 04:51
| Instead, we can use '''name''' of the '''argument''' to pass a '''value '''to it.

|-
| 04:57
| Let us define a '''function''' with name '''marks '''which takes three marks as '''arguments'''.

|-
| 05:04
| Type as shown.

Then we will call the '''marks function''' without specifying the '''keywords'''.

|-
| 05:11
| Type, '''marks '''''inside brackets '''''34''''' comma '''''23''''' comma '''''45'''

|-
| 05:18
| We get the output as “'''first: 34 second: 23 and third: 45'''”

|-
| 05:24
| Here the '''values''' '''34, 23 '''and''' 45 '''are passed according to the '''position.'''

|-
| 05:31
| To confirm this, we will try with different values.

|-
| 05:35
| Type, '''marks '''''inside brackets '''''34''''' comma '''''45 '''''comma '''''23'''

|-
| 05:42
| We can see that the printed '''values''' are changed since they are passed according to the '''position'''.

|-
| 05:49
| Now let us pass two values without '''keyword''' and other one with '''keyword.'''

|-
| 05:55
| Type, '''marks '''''inside brackets '''''34 '''''comma '''''23 '''''comma '''''third''''' is equal to '''''45'''

|-
| 06:04
| Here first two values are passed according to the position and the third as '''keyword argument'''.

|-
| 06:12
| But, the '''keyword arguments''' should be specified at the end.

|-
| 06:17
| Now type, '''marks '''''inside brackets '''''34 '''''comma '''''second '''''is equal to '''''23 '''''comma '''''45'''

|-
| 06:26
| We get the '''SyntaxError, positional argument follows keyword argument.'''

|-
| 06:32
| This is because here the '''keyword argument''' is not specified at the end.

|-
| 06:38
| We can pass all the '''parameters''' as '''keyword arguments'''.

|-
| 06:43
| Type, '''marks '''''inside brackets '''''second '''''is equal to '''''34 '''''comma '''''first''''' is equal to '''''23 '''''comma '''''third''''' is equal to '''''45'''

|-
| 06:54
| Here even though the order of '''keyword''' is changed, we get the output as:

“'''first: 23 second: 34 and third: 45'''”

|-
| 07:03
| Next we will learn to define a '''function''' to take only '''keyword arguments.'''

|-
| 07:09
| Type as shown.

|-
| 07:12
| Then to call the '''function''', type,

'''marks '''''inside brackets '''''second '''''is equal to '''''34 '''''comma '''''first '''''is equal to '''''23 '''''comma '''''third '''''is equal to '''''45'''

|-
| 07:25
| Note the '''asterisk''' symbol at the starting of '''parameters'''.

|-
| 07:29
| It restricts the '''function''' to accept '''keyword''' only '''arguments.'''

|-
|07:34
| Again we will try to call the '''function''' without '''keyword arguments.'''

|-
| 07:39
| Type, '''marks '''''inside brackets '''''45 '''''comma''''' 34 '''''comma''''' 23'''

|-
| 07:46
| It gives a '''TypeError '''as''' marks() takes 0 positional arguments but 3 were given.'''

|-
| 07:53
| This way we can enforce usage of '''keyword '''only '''arguments''' without''' positional arguments.'''

|-
| 08:00
| Next let us learn to use '''arbitrary arguments'''.

|-
| 08:05
| We may not always know in advance the number of '''arguments''' that will be passed into a '''function'''.

|-
| 08:12
| Use an asterisk(*) before an '''argument''' name to denote '''arbitrary''' number of '''arguments'''.

|-
| 08:19
| We can define a '''function''' to accept any number of '''positional arguments'''.

|-
| 08:25
| Type as shown.

Then type, '''family '''''inside brackets inside double quotes '''''Duryodhana '''''comma inside double quotes '''''Dushasana'''

|-
| 08:38
| Here, we have called the '''function''' with multiple '''arguments'''.

|-
| 08:43
| These '''arguments''' get wrapped up into a '''tuple''' while passed into the '''function'''.

|-
| 08:49
| Now type as shown.

|-
| 08:53
| As you can see, we can call the '''function family '''with more values passed to the '''names argument'''.

|-
| 09:01
| We have passed 2 values in the first '''call''' and 4 values in the second '''call''' to the '''function family'''.

|-
| 09:09
| In both cases these values are assigned to the '''parameter names.'''

|-
| 09:15
| We can also define a '''function''' to receive '''arbitrary''' number of '''keyword arguments.'''

|-
| 09:21
| Type as shown.

Then to call the '''function''' type as shown.

|-
| 09:29
| The '''person function''' prints a '''dictionary''' of '''keyword arguments''' passed to it.

|-
| 09:35
| Note the '''double asterisk symbol '''at the beginning of the '''parameter''' names.

|-
| 09:40
| It enables to pass zero or more '''keyword arguments'''.

|-
| 09:45
| Note: '''Single asterisk (*)''' symbol is used to accept '''arbitrary number of positional arguments.'''

|-
| 09:53
| And the '''double asterisk (**) '''symbol is used to accept '''arbitrary number of keyword arguments.'''

|-
| 10:01
| Now call the '''person function''' as shown.

|-
| 10:06
| Here we have passed 3 '''keyword arguments''' in the first case and 4 in the second case.

|-
| 10:14
| The '''function''' prints a '''dictionary''' of '''keyword arguments''' with values.

|-
| 10:20
| '''Python''' also provides '''built-in functions. '''

|-
| 10:22
| Some are '''abs()'''

'''any()'''

|-
| 10:29
| '''dir()'''

'''help()'''

|-
| 10:33
| You can visit this link to get the full list of '''built-in functions''' and their usage.

|-
| 10:39
| This brings us to the end of this tutorial. Let us summarize.

|-
| 10:45
| In this tutorial, we have learned to define '''functions''' with, '''Default arguments''', '''keyword arguments''' and '''Arbitrary arguments'''

|-
| 10:55
| Here are some self assessment questions for you to solve.

|-
| 11:00
| All the '''arguments''' of a '''function''' cannot have default values. - True or False?

|-
| 11:08
| The following is a valid '''function''' definition. True or False?

|-
| 11:15
| While '''calling''' a '''function''', which one is correct in the following.

|-
| 11:20
| And the answers,

First. False. All the '''arguments''' of a '''Python function''' can have default values.

|-
| 11:28
| Second. False. All the '''parameters''' with default '''arguments''' should be defined at the end.

|-
| 11:35
| Third. While '''calling''' a '''function''', only '''keyword arguments''' can be in any order, but should be called at the end.

|-
| 11:44
| Please post your timed queries in this forum.

|-
| 11:48
| Please post your general queries on Python in this forum.

|-
| 11:53
| FOSSEE team coordinates the TBC project.

|-
| 11:57
| Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this website.

|-
| 12:06
| This is Priya from IIT Bombay signing off. Thanks for watching.

|}

Python-3.4.3/C4/Advanced-Features-of-Functions/English-timed - Revision history

PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Advanced Features of Functions'''. |- | 00:0..."