Calculating the sum of all columns of a 2D NumPy array
Last Updated :
02 Sep, 2020
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Let us see how to calculate the sum of all the columns of a 2 dimensional NumPy array.
Example :
python3
Output :
Python3
Output :
Input : [[1, 2, 3, 4, 5], [5, 6, 7, 8, 9], [2, 1, 5, 7, 8], [2, 9, 3, 1, 0]] Output : [10, 18, 18, 20, 22] Input : [[5, 4, 1, 7], [0, 9, 3, 5], [3, 2, 8, 6]] Output : [8, 15, 12, 18]Approach 1 : We will be using the
sum()
method. We will pass parameter axis = 0
to get the sum columns wise.
# importing numpy
import numpy as np
# initialize the 2-d array
arr = np.array([[1, 2, 3, 4, 5],
[5, 6, 7, 8, 9],
[2, 1, 5, 7, 8],
[2, 9, 3, 1, 0]])
# calculating column wise sum
sum_2d = arr.sum(axis = 0)
# displaying the sum
print("Column wise sum is :\n", sum_2d)
Column wise sum is : [10 18 18 20 22]Approach 2 : We can also use the
numpy.einsum()
method, with parameter 'ij->j'
.
# importing numpy
import numpy as np
# initialize the 2-d array
arr = np.array([[1, 2, 3, 4, 5],
[5, 6, 7, 8, 9],
[2, 1, 5, 7, 8],
[2, 9, 3, 1, 0]])
# calculating column wise sum
sum_2d = np.einsum('ij->j', arr)
# displaying the sum
print("Column wise sum is :\n", sum_2d)
Column wise sum is : [10 18 18 20 22]