PoojaMoolya at 12:55, 1 August 2019

2019-08-01T12:55:29Z

Pratik kamble: Created page with "{|border=1 | ''' Time ''' | '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Getting started with arrays'''. |- | 00:06 | In this tutorial, you will learn..."

2019-05-31T13:02:25Z

Created page with "{|border=1 | ''' Time ''' | '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Getting started with arrays'''. |- | 00:06 | In this tutorial, you will learn..."

New page

{|border=1
| ''' Time '''
| '''Narration'''

|-
| 00:01
| Welcome to the spoken tutorial on '''Getting started with arrays'''.

|-
| 00:06
| In this tutorial, you will learn to,

Create '''arrays''' using data

Create '''arrays''' from '''lists'''

Perform basic '''array''' operations

Create an '''identity matrix '''

and Use the '''method zeros'''

|-
|00:24
|To record this tutorial, I am using

'''Ubuntu Linux 16.04''' operating system

'''Python 3.4.3 '''and

'''IPython 5.1.0'''

|-
| 00:39
| To practice this tutorial, you should know how to use '''Lists.'''If not, see the relevant '''Python''' tutorials on this website.

|-
|00:50
| '''Arrays''' are '''homogeneous data structures'''. All '''elements''' in it must be of same '''data type.'''

|-
|00:58
|In this tutorial, we will be using''' numpy library''' which we used in earlier tutorial.

|-
| 01:05
| Let us first open the '''terminal '''by pressing '''Ctrl+Alt+T '''keys simultaneously.

|-
| 01:12
| Let us start '''ipython''' by typing '''ipython3 '''and press '''Enter.''' We can see the '''ipython prompt'''.

|-
| 01:22
| Now we will '''import numpy'''. Type, '''import numpy as np''' and press '''Enter.'''

|-
| 01:32
| Now let us see how to create '''arrays. '''

|-
| 01:36
| From here onwards, please remember to press the '''Enter''' key after typing every command on the '''terminal'''.

|-
| 01:44
| Type, '''a1 '''''is equal to''''' np '''''dot '''''array '''''inside parentheses inside square brackets '''''1 '''''comma '''''2 '''''comma '''''3 '''''comma '''''4 '''

|-
| 01:54
| Type '''a1 ''' Notice that we have created a '''one dimensional array''' here.

|-
| 02:02
| Also notice that the object we passed to create an '''array '''is a '''list,''' i.e '''a1.'''

|-
| 02:09
| Next we will see how to create '''two dimensional array'''.

|-
| 02:14
| Two dimensional '''array''' is created by converting a '''list''' of '''lists''' to an '''array.'''

|-
| 02:20
| Type, '''a2 '''''is equal to''''' np '''''dot '''''array '''''inside parentheses inside square brackets ''again'' inside square brackets 1 comma 2 comma 3 comma 4 comma inside square brackets 5 comma 6 comma 7 comma 8''

|-
| 02:38
| Type '''a2''' This is our '''2-dimensional array'''.

|-
| 02:44
| Next we will see about '''arange method'''.

|-
| 02:48
| To arrange the '''elements''' in an '''array''' we use '''arange method.''' The syntax is shown here.

|-
| 02:57
| Type '''ar''''' is equal to'' '''np''' ''dot '''''arange''' ''inside parentheses'' 1 ''comma'' 9.

|-
| 03:04
| Type '''print''' ''inside parentheses'' '''ar'''

|-
| 03:08
| Here, 1 is the '''start''' value and 9 is the '''stop''' value.

|-
| 03:13
| As you can see, we obtained a '''one dimensional array''' between 1 and 9 with 1 included and 9 excluded.

|-
| 03:22
| It will give the '''elements''' one less than the stop value.

|-
| 03:26
| Can we make a '''two dimensional array''' of order 2 by 4? Yes, we can do it.

|-
| 03:33
| We will use '''reshape method''' to change the shape of an array.

|-
| 03:38
| The syntax is: '''object.reshape '''''inside parentheses '''''rows '''''comma''''' columns'''

|-
| 03:45
| Switch back to the '''terminal'''.

|-
| 03:48
| Type, '''ar''' ''dot'' '''reshape''''' inside parentheses'' '''2''''' comma'' '''4'''.

|-
| 03:54
| Type''' ar''' Shape of the original '''array ar '''is not changed.

|-
| 04:00
| If you want to change the shape of the original '''array''', type '''ar '''''dot '''''shape '''''is equal to''''' '''''inside parentheses'' '''2''''' comma'' '''4'''.

|-
| 04:11
| Type''' ar''' We can see that the shape of the original '''array ar''' is changed now.

|-
| 04:20
| To find the shape of an '''array''' we can use the '''method shape.'''

|-
| 04:25
| It returns a '''tuple''' of the '''shape''' of an '''array.'''

A '''tuple''' is nothing but an '''ordered list''' of '''elements'''.

|-
| 04:34
| Let us check the shape of the '''arrays''' we have created so far.

|-
| 04:38
| Type '''a2 '''''dot '''''shape ''' '''a2.shape''' object is a '''tuple''', and it returned a '''tuple''' '''(2, 4)'''.

|-
| 04:47
| Pause the video here, try out the following exercise and resume the video.

|-
| 04:52
| Find out the shape of the '''arrays a1 '''and''' ar '''which we have created earlier in this tutorial.

|-
| 04:58
| Let us see the solution. Type, '''a1 '''''dot '''''shape '''

|-
| 05:04
| Since '''a1''' is a '''single dimensional array''', the '''column''' is empty.

|-
| 05:09
| Type, '''ar '''''dot '''''shape ''' '''ar''' is a '''two dimensional array'''.

|-
| 05:15
| Now let us try to create a new '''array''' with elements of different '''datatypes'''.

|-
| 05:21
| Type '''a3 '''''is equal to''''' np '''''dot '''''array '''''inside parentheses inside square brackets '''''1 '''''comma '''''2 '''''comma '''''3 '''''comma inside single quotes '''''a string '''

|-
| 05:33
| '''Arrays''' handle '''elements''' with the same '''datatype'''.

|-
| 05:37
| Here we are handling with different '''datatypes'''. So it should give us error.

|-
| 05:44
| Type '''a3''' But we did not get any error. Because all the '''elements''' get implicitly converted as '''strings'''.

|-
| 05:54
| This is how '''array''' works.

|-
| 05:57
| Note that the output mentions '''dtype=’<U21''''

|-
| 06:04
| A''' dtype''' is the '''datatype '''required to hold the objects in sequence.

|-
| 06:10
| The characters of '''dtype''' i.e. '''’<U21' '''might differ with '''python''' version.

|-
| 06:17
| Next we will see about '''identity matrix'''.

|-
| 06:21
| It is a '''square matrix''' of order (n,n) with ones on the '''main diagonal''' and all other '''elements''' as zeros.

|-
| 06:29
| The syntax is '''identity '''''inside parentheses''' ''n.'''

|-
| 06:34
| Let us see how to create a 2 by 2 '''identity matrix'''.

|-
| 06:39
| Type, '''np''' ''dot''' ''identity '''''inside parentheses '''''2.'''

|-
| 06:45
| We can see all ones in the '''main diagonal''' as expected.

|-
| 06:50
| Next is '''Zeros method'''.

|-
| 06:53
| It creates an '''m by n '''matrix with all '''elements''' as 0.

|-
| 06:58
| The Syntax is: '''zeros '''''inside parentheses inside parentheses''' ''m, n'''

|-
| 07:05
| Let us create an '''array''' of the shape (4, 5) with all the '''elements zero'''.

|-
| 07:11
| Type, '''np '''''dot '''''zeros '''''inside parentheses inside parentheses '''''4 '''''comma '''''5'''''.''

|-
| 07:18
| The default output of '''identity''' and '''zeros method '''are in '''float datatype'''.

|-
| 07:24
|Explore the below '''functions''' on your own:

'''zeros_like'''

'''ones'''

'''ones_like'''

|-
| 07:34
| Try the following.

|-
| 07:36
| First check the value of '''a1''' which we assigned earlier.

|-
| 07:41
| Type '''a1 ''' We see that '''a1''' is a '''single dimensional array.'''

|-
|07:48
| Let us now try '''a1 '''''multiplied by '''''2''' It returned a new '''array''' with all the '''elements''' multiplied by 2.

|-
| 07:58
| Now let us again check the contents of '''a1.''' Note that the value of '''a1''' still remains the same.

|-
| 08:06
| Similarly we will try with addition.

|-
| 08:10
| Type, '''a1 '''''plus '''''2 ''' It returns a new '''array''', with all the '''elements''' summed with two.

|-
| 08:18
| Type '''a1''' . But again notice that the value of '''a1''' has not been changed.

|-
| 08:26
| Let us try with '''a1 '''''plus equal to '''''2 '''

|-
| 08:31
| Type, '''a1 ''' This will change the''' array a1 '''itself as we are assigning the new output to '''a1'''.

|-
| 08:41
| We can use all the mathematical operations with '''arrays'''. Next, we will see how to add two '''arrays'''.

|-
| 08:50
| Type, '''a1 '''''is equal to''''' np '''''dot '''''array '''''inside parentheses inside square brackets '''''1, 2, 3, 4'''

|-
| 09:00
| Type '''a2 '''''is equal to''''' np '''''dot '''''array '''''inside parentheses inside square brackets '''''5, 6, 7, 8'''

|-
| 09:10
| Type '''a1 '''''plus''''' a2'''This returns an '''array''' by adding '''element''' by '''element'''.

|-
| 09:18
| Type '''a1 '''''multiplied by''''' a2''' It returns an '''array''' with '''element''' by '''element''' multiplication.

|-
| 09:27
| This brings us to the end of the end of this tutorial.

|-
| 09:31
| In this tutorial, we have learnt to,

1. Create an '''array''' using the '''array() function'''.

2. Perform some basic operations on '''arrays''' like addition and multiplication.

3. Use methods like -

'''shapearange, reshapeidentity '''and'''zeros'''

|-
| 09:50
| Here is a self assessment question for you to solve

|-
| 09:54
| '''x '''''is equal to''''' np.array '''''inside parentheses inside square brackets''' ''1, 2, 3, '''''inside square brackets''' ''5, 6, 7''' is a valid statement?

True
False

|-
| 10:10
| And the answer is False.

|-
| 10:13
| The correct way is to assign the '''elements''' as a '''list''' of '''lists''' and then convert it to an '''array.'''

|-
| 10:19
| That is '''x '''''is equal to''''' np.array '''''inside parentheses inside square brackets again inside square brackets '''''1, 2, 3, '''''inside square brackets '''''5, 6, 7'''

|-
| 10:35
| Please post your timed queries in this forum.

|-
| 10:39
| Please post your general queries on '''Python''' in this forum.

|-
| 10:44
| FOSSEE team coordinates the TBC project.

|-
| 10:48
| Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.For more details, visit this website.

|-
|10:57
| This is Priya from IIT Bombay signing off. Thanks for watching.

|}

@@ Line 357: / Line 357: @@
 . Use methods like -
-'''shapearange, reshapeidentity '''and'''zeros'''
+'''shape , arange, reshape, identity '''and'''zeros'''
 |-

Python-3.4.3/C3/Getting-started-with-arrays/English-timed - Revision history

PoojaMoolya at 12:55, 1 August 2019

Pratik kamble: Created page with "{|border=1 | ''' Time ''' | '''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Getting started with arrays'''. |- | 00:06 | In this tutorial, you will learn..."