Multi-dimensional lists in Python

Last Updated : 09 Dec, 2018

There can be more than one additional dimension to lists in Python. Keeping in mind that a list can hold other lists, that basic principle can be applied over and over. Multi-dimensional lists are the lists within lists. Usually, a dictionary will be the better choice rather than a multi-dimensional list in Python.

Accessing a multidimensional list:

Approach 1:

# Python program to demonstrate printing 
# of complete multidimensional list 
a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]] 
print(a) 

Output:

[[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]]

Approach 2: Accessing with the help of loop.

# Python program to demonstrate printing 
# of complete multidimensional list row 
# by row. 
a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]] 
for record in a: 
    print(record) 

Output:

[2, 4, 6, 8, 10]
[3, 6, 9, 12, 15]
[4, 8, 12, 16, 20]

Approach 3: Accessing using square brackets.
Example:

# Python program to demonstrate that we 
# can access multidimensional list using 
# square brackets 
a = [ [2, 4, 6, 8 ],  
    [ 1, 3, 5, 7 ],  
    [ 8, 6, 4, 2 ],  
    [ 7, 5, 3, 1 ] ]  
          
for i in range(len(a)) :  
    for j in range(len(a[i])) :  
        print(a[i][j], end=" ") 
    print()     

Output:

Creating a multidimensional list with all zeros:

# Python program to create a m x n matrix 
# with all 0s 
m = 4
n = 5
  
a = [[0 for x in range(n)] for x in range(m)] 
print(a) 

Output:

[[0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0]]

Methods on Multidimensional lists

1. append(): Adds an element at the end of the list.
Example:

# Adding a sublist 
  
a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]] 
a.append([5, 10, 15, 20, 25]) 
print(a) 

Output:

[[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20], [5, 10, 15, 20, 25]]

2. extend(): Add the elements of a list (or any iterable), to the end of the current list.

# Extending a sublist  
  
a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]] 
a[0].extend([12, 14, 16, 18]) 
print(a) 

Output:

[[2, 4, 6, 8, 10, 12, 14, 16, 18], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]]

3. reverse(): Reverses the order of the list.

# Reversing a sublist  
  
a = [[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]] 
a[2].reverse() 
print(a) 

Output:

[[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [20, 16, 12, 8, 4]]

Statement, Indentation and Comment in Python

Kanishk_Verma

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Multi-dimensional lists in Python

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