Python – Remove front column from Matrix

Sometimes, while working with Matrix data, we can have stray element that attached at front end of each row of matrix. This can be undesired at times and wished to be removed. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop + del + list slicing
The combination of above functionalities can be used to perform this task. In this, we run a loop for each row in matrix and remove the front element using del.

# Python3 code to demonstrate working of
# Remove front column from Matrix
# Using loop + del + list slicing

# initialize list
test_list = [[1, 3, 4], [2, 4, 6], [3, 8, 1]]

# printing original list
print("The original list : " + str(test_list))

# Remove front column from Matrix
# Using loop + del + list slicing
for ele in test_list: del ele[0]

# printing result
print("Matrix after removal of front column : " + str(test_list))

Output :

The original list : [[1, 3, 4], [2, 4, 6], [3, 8, 1]]
Matrix after removal of front column : [[3, 4], [4, 6], [8, 1]]

Method #2 : Using list comprehension + list slicing
The combination of above functions can also be used to perform this task. In this, we just iterate for each row and delete front element using list slicing.

# Python3 code to demonstrate working of
# Remove front column from Matrix
# Using list comprehension + list slicing

# initialize list
test_list = [[1, 3, 4], [2, 4, 6], [3, 8, 1]]

# printing original list
print("The original list : " + str(test_list))

# Remove front column from Matrix
# Using list comprehension + list slicing
res = [ele[1:] for ele in test_list]

# printing result
print("Matrix after removal of front column : " + str(res))

Output :

The original list : [[1, 3, 4], [2, 4, 6], [3, 8, 1]]
Matrix after removal of front column : [[3, 4], [4, 6], [8, 1]]