Calculate the sum of all columns in a 2D NumPy array

Let us see how to calculate the sum of all the columns in a 2D NumPy array.
Method 1 : Using a nested loop to access the array elements column-wise and then storing their sum in a variable and then printing it.
Example 1: 
 

Output : 
 

2D Array:
[[ 1 2 3]
 [ 4 5 6]
 [ 7 8 9]
 [10 11 12]]

Column-wise Sum:
22 26 30 

Example 2 : 
 

Output : 
 

2D Array:
[[1.2 2.3]
 [3.4 4.5]]

Column-wise Sum:
4.6 6.8 

Method 2: Using the sum() function in NumPy, numpy.sum(arr, axis, dtype, out) function returns the sum of array elements over the specified axis. To compute the sum of all columns the axis argument should be 0 in sum() function.
Example 1 : 
 

Output : 
 

2D Array:
[[ 1 2 3]
 [ 4 5 6]
 [ 7 8 9]
 [10 11 12]]

Column-wise Sum:
22 26 30

Example 2 : 
 

Output : 
 

2D Array:
[[1.2 2.3]
 [3.4 4.5]]

Column-wise Sum:
4.6 6.8