Array in python

1.Array :

1. array is a data structure which can hold more than one value at a time

2. array is collection of element of same data type

3. Index value of an array is all ways start from zero which means if length

of an array is n , then its index number is " n - 1 "

4. Array and list are almost similar ,But a key difference is list can have a

member/elements of differnt data types together But an array can have

only elements of same data type

5. array in python is mutable , it means we can add and delete the elements in array

2.Create an array :

To create an array in python , we have to import a module of an array

There are three ways to import a module of an array

Without ALIAS	With ALIAS	Using ‘Star * ’
Import array	Import array as arr	from array import *

Using a star ' * ' is most likely use method ,because it will reduce length of code

' star ' means import all function in array module

3.Declare an array :
To declare an array we have to specify two things .

(1) Data Type

(2) Value's

To define a data type ,user should have knowledge of Type code.
Python provide some special type code do define different data types

TYPE CODE	MEANING	SIZE
b	Signed char	1
B	Unsigned char	1
h	Short signed int	2
H	Short unsigned int	2
i	Signed int	2
I(Capital i)	Unsigned int	2
l(small L)	Long signed int	4
L	Long unsigned int	4
f	float	4
d	double	8

Signed Int : It can hold zero ,Positive and Negative number
Unsigned Int: It can hold Only zero and positive number

Signed char : Its range is from -128 to 127
Unsigned char : Its range is from 0 to 255

Syntax :To print an array elements and find its length print its data type

from array import *
a = array ('i',[2,4,5,-9,-8])
print("array elements are" )
print(a)
print(array.len(a))
print(a.typecode)

Assessing array elements :

1.We can access an array elements using there index value
2.Indexing start from zero
3.In indexing Normal traversal is from left to right

4.Important point to note that negative indexing also exist in python and the
traversal for negative indexing is from right to left

code:

from array import *
a = array ('i',[2,4,5,-9,-8])
b=a[2]
print(b)
b=a[-2]
print(b)

Output = 5, -9

We had all ready discuss that array in python is mutable , so we can add and

remove/delete the elements from it

Python provides some inbuild function to add and remove the elements

Inserting an elements :

To insert an element python have 2 inbuild function

Name of Function	append()	Insert()
Description	Used when we want to add a single element at the end of an array.	It will add an element at particular Place where user Want . Syntax

a.insert(2,3)

First number is index number or a position where user wants to add element, where second one is value

To add more than one element at the end python provide one another function extend()

But to use this function multiple values must be written in " [] " square brackets

or compiler will through an error

e.g.

from array import *
a = array ('i',[2,4,5,-9,-8])
a.extend([2,5])
print(a)

output :

array('i', [2, 4, 5, -9, -8, 2, 5])

Removing an Element :

To Delete an element python provide 2 functions

Name	pop()	remove()
Description	In pop() function user have to mention index number ,if not then By default it will remove the last one	In remove() function user have to mention the value from array which has to remove

Concatenate Array :

Concatenation means take two or more array of same type and join them ,by default it will

concatenate row wise

from array import *

a=array('i',[1,2,3,4])

b=array('i',[5,6,7,8])

c=array('i',[]) #blank array

c=a+b

print ("Array c =",c)

Array input from user:

We can take values of an array from user

from array import *
a=array('i',[])
n=int(input("Enter size of an array"))
for i in range (n):
x=int(input("Enter values of an array"))
a.append(x)

print(a)

output :

Enter size of an array5
Enter values of an array2
Enter values of an array3
Enter values of an array6
Enter values of an array8
Enter values of an array9
array('i', [2, 3, 6, 8, 9])

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Array in python