Python - Arrays

Python - Arrays

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Note: Python does not have inbuilt array support, but the can be used as an array.

The Array is a type of data container which is used to store multiple data elements in one variable. Elements of the array can be accessed using its index number.

Create an Array

Array (List) can be created by separating it's elements using comma (,) and enclosing them with square bracket [ ].

Example

Info = ['John', 'Marry', 'Kim']  
print(Info)

Output

['John', 'Marry', 'Kim']

Access element of an Array

An element of a array can be accessed with it's index number. In Python, index number starts with 0 in forward direction and -1 in backward direction. The below figure and example describe the indexing concept of an array.

Array Indexing:

Python Arrays Indexing

Example

weekday = ['MON', 'TUE', 'WED', 'THU', 'FRI']

#forward indexing
print(weekday[1]) 

#backward indexing 
print(weekday[-1])

Output

TUE 
 
FRI

Access range of elements of an Array

Range of elements of an array can be selected using statement like [start_index : end_index] where end_index is excluded. If start_index and end_index are not mentioned then it takes first and last index numbers of the array respectively.

Example

weekday = ['MON', 'TUE', 'WED', 'THU', 'FRI']
print(weekday[1:3])
print(weekday[-5:-1])

print(weekday[1:])
print(weekday[:-3])

print(weekday[:])

Output

['TUE', 'WED']                         
['MON', 'TUE', 'WED', 'THU']            

['TUE', 'WED', 'THU', 'FRI']            
['MON', 'TUE']                          

['MON', 'TUE', 'WED', 'THU', 'FRI']

Modify element's value

To change element's value, assign new value using it's index.

Example

Info = ['John', 'Marry', 'Kim'] 
#value at index=0 changed to 'Jo'
Info[0] = 'Jo'  
print(Info)

Output

['Marry', 'Jo', 'Kim']

Add elements in an Array

Below mentioned methods are used to add elements in an array:

  • append() - add an element to the end of an array.
  • insert() - insert an element at specified index of the array.

Example

days = ['MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT']
# add this element in last of the array
days.append('SUN')   
print(days)

month = ['JAN', 'FEB', 'MAR', 'MAY']
# add 'APR' at index=3 of the array
month.insert(3,'APR') 
print(month)

Output

['MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT', SUN']

['JAN', 'FEB', 'MAR', 'APR', 'MAY']

Delete elements of an Array

Below mentioned methods/keywords is used to delete elements from an array:

  • remove() - deletes first occurrence of a specified element from the array.
  • pop() - deletes element at specified index or last element if index is not specified.
  • clear() - deletes all elements of an array.
  • del - deletes a element or range of elements or array itself.

Example

number = [10, 50, 50, 100, 1000]
#delete first occurrence of 50.
number.remove(50)    
print(number)

number = [10, 50, 50, 100, 1000]
#delete element at index=3.
number.pop(3)        
print(number)

number = [10, 50, 50, 100, 1000]
#delete last element from the array.
number.pop()        
print(number)

number = [10, 50, 50, 100, 1000]
#delete all elements from the array.
number.clear()     
print(number)

Output

[10, 50, 100, 1000]

[10, 50, 50, 1000]

[10, 50, 50, 100]

[]

The del keyword is used to delete an element or range of elements or array itself.

Example

number = [10, 50, 50, 100, 1000]
#delete element at index=3.
del number[3]       
print(number)

number = [10, 50, 50, 100, 1000]
#delete element at index=1,2 and 3.
del number[1:4]     
print(number)

number = [10, 50, 50, 100, 1000]
#delete array 'number'.
del number          
print(number)

Output

[10, 50, 50, 1000, 1000]

[10, 1000, 1000]

NameError: name 'number' is not defined

Array length

The len() function can be used to find out total number of elements in an array.

Example

number = [10, 50, 50, 100, 1000, 1000]
print(len(number))

Output

6

Loop over Array

For loop over array:

for loop can be used to access each element of an array.

Example

colors = ['Red', 'Blue', 'Green']
for x in colors:
    print(x)

Output

Red
Blue
Green

While loop over Array

By using while loop and len() function, each element of an array can be accessed.

Example

colors = ['Red', 'Blue', 'Green']
i = 0
while i < len(colors):
    print(colors[i])
    i = i + 1

Output

Red
Blue
Green

Check an element in the Array

If control statement is used to check whether the array contains specified element or not.

Example

colors = ['Red', 'Blue', 'Green']
if 'white' in colors:
  print('Yes, white is an element of colors.')
else:
  print('No, white is not an element of colors.')

Output

No, white is not an element of colors.


Recommended Pages

  • Next Page
  • Note:
  • Python does not have inbuilt array support, but the
  • Python Lists
  • can be used as an array.

List Methods & Functions
MethodsDescription
Adds a specified element to the end of the list
The Deletes all elements from the list
Array Creates a copy of the list into a new list
is a type of data container which is used to store multiple data elements in one variable. Elements of the array can be accessed using its index number. Returns the number of occurrence of a specified element in the list
Adds an element or iterable at the end of the list
Create an Array Returns the index of first occurrence of a specified element in the list
Adds a specified element at specified index in the list
Array (List) can be created by separating it's elements using comma (,) and enclosing them with square bracket [ ]. Deletes an element at specified index or last element of the list
Deletes first occurrence of a specified element in the list
Reverses order of all elements in the list
Example Sorts elements of the list in ascending or descending order with specified sorting criteria
FunctionsDescription
Returns total number of elements in the list
Info = ['John', 'Marry', 'Kim'] print(Info) List function/constructor is used to create list from iterable like list, tuple, set, string and dictionary, etc.
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