summing np array code example

Example 1: python get a vector of row sums from an array

# Basic syntax:
np.sum(your_array, axis=1).tolist()
# Where axis=1 sums across rows and axis=0 sums across columns

# Example usage:
import numpy as np
your_array = np.array([range(0,4),range(3,7),range(1,5),range(2,6)])
print(your_array)
--> [[0 1 2 3]
 	 [3 4 5 6]
     [1 2 3 4]
     [2 3 4 5]]

np.sum(your_array, axis=0).tolist() # Return column sums
--> [6, 10, 14, 18]
np.sum(your_array, axis=1).tolist() # Return row sums
--> [6, 18, 10, 14]

Example 2: sum of a numpy array

>>> np.sum([0.5, 1.5])
2.0
>>> np.sum([0.5, 0.7, 0.2, 1.5], dtype=np.int32)
1
>>> np.sum([[0, 1], [0, 5]])
6
>>> np.sum([[0, 1], [0, 5]], axis=0)
array([0, 6])
>>> np.sum([[0, 1], [0, 5]], axis=1)
array([1, 5])
>>> np.sum([[0, 1], [np.nan, 5]], where=[False, True], axis=1)
array([1., 5.])