Boolean Indexing with NumPy
Use boolean indexing in NumPy arrays to assign values. The example below assigns a zero to array items that are less than zero.
import numpy as np
nums = np.array([-1, 3, 6, -0.2, -4])
nums[nums < 0] = 0
print(nums)
# array([0., 3., 6., 0., 0.])