Python two or multi dimensional List: Declaring adding deleting rows columns and elements

Though Numpy library or Pandas DataFrame is preferred for matrix handling but still we can use multidimensional lists in python for many requirements.
Creating two dimensional list

my_list=[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0],
 [3, 9, 1, 1, 5], [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]

Displaying all elements as matrix

my_list=[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0], [3, 9, 1, 1, 5],
 [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]
for i in my_list:
    print(i)

Output

[1, 0, 0, 4, 6]
[3, 9, 8, 0, 0]
[3, 9, 1, 1, 5]
[0, 9, 3, 0, 8]
[8, 6, 1, 9, 7]

Displaying elements

print(my_list[3][4]) # 8

Displaying a row of data , 0th row is first row , so this will display the 3rd row from top.

print(my_list[2]) # [3, 9, 1, 1, 5]

Displaying column ( 2nd column , first column is 0th column )

for x in my_list: 
#    print(x[3])

Or we can also write like this.

[x[3] for x in my_list]

Output

[4, 0, 1, 0, 9]

Display all elements of two dimensional list.
Here len() returns the number of elements in each row.

l1=[['abc','def','ghi','jkl'],
    ['mno','pkr','frt','qwr'],
    ['asd','air','abc','zpq'],
    ['zae','vbg','qir','zab']]

for my_row in l1: # Each row of data from the list 
    for data in range(len(my_row)): # Index position of Each element in the row
        print(my_row[data],end=' ') # Print each element without line break 
    print('') # One line break after each row of data

Output

abc def ghi jkl 
mno pkr frt qwr
asd air abc zpq
zae vbg qir zab

Deleting rows and columns

Delete 2nd row

my_list=[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0], [3, 9, 1, 1, 5], [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]
my_list.pop(2) # delete 2nd row , First row is 0th row
print(my_list)

Output

[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0], [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]

Delete column

my_list=[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0], [3, 9, 1, 1, 5], [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]
[x.pop(3) for x in my_list] # delete 3rd column, 
print(my_list)

Output

[[1, 0, 0, 6], [3, 9, 8, 0], [3, 9, 1, 5], [0, 9, 3, 8], [8, 6, 1, 7]]

Or we can delete column like this

for x in my_list:
    x.pop(3)
print(my_list)

Creating a two dimensional List by using random numbers

from random import randrange
n=5 # dimension of the matrix 
my_list=[] # declare a list 

for i in range(0,n):
    l1=[]  
    for j in range(0,n):
        x=randrange(10)
        l1.append(x) # adding element to the list 
        
    my_list.append(l1)
print(my_list)

Output

[[5, 1, 7, 6, 6], [9, 0, 1, 1, 2], [9, 2, 2, 7, 4], [6, 2, 6, 9, 6], [7, 1, 6, 4, 5]]

Transpose of a matrix

We used zip here

my_list=[[1,2], [3,4], [5,6]]
for row in my_list:
    print(row)
print("Transpose the matrix")    

#list(map(list, zip(*my_list)))
my_list_T=map(list, zip(*my_list))
list(my_list_T)

Output

[1, 2]
[3, 4]
[5, 6]
Transpose the matrix
[[1, 3, 5], [2, 4, 6]]

Sum of diagonal numbers of a square matrix

my_list=[[1, 0, 0, 4, 6], [3, 9, 8, 0, 0], [3, 9, 1, 1, 5], [0, 9, 3, 0, 8], [8, 6, 1, 9, 7]]
for i in my_list:
    print(i)

Output

[1, 0, 0, 4, 6]
[3, 9, 8, 0, 0]
[3, 9, 1, 1, 5]
[0, 9, 3, 0, 8]
[8, 6, 1, 9, 7]

List Matrix Multiplication without using built-in functions

Python

All String methods tuple Python- Tutorials

Subhendu Mohapatra

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Multi dimensional LIST in Python

Deleting rows and columns

Transpose of a matrix

Sum of diagonal numbers of a square matrix

Subhendu Mohapatra