Fran Ahedo Guerrero Fran Ahedo Guerrero - 4 months ago 19
Python Question

How to delete numbers from a vector?

I have this vector

v = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20)


I want to remove the multiples of 2 and 3. How would I do this? I tried to do this but I can not:

v = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20)
Mul3 = np.arange (1.21,3)
Mul2 = np.arange (1.21.2)
V1 = v [-mul2]
V2 = v1 [-mul3]

Answer Source

Given that you use NumPy already you can use boolean array indexing to remove the multiples of 2 and 3:

>>> import numpy as np
>>> v = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20)  # that's a tuple
>>> arr = np.array(v)  # convert the tuple to a numpy array
>>> arr[(arr % 2 != 0) & (arr % 3 != 0)]
array([ 1,  5,  7, 11, 13, 19])

The (arr % 2 != 0) creates a boolean mask where multiples of 2 are False and everything else True and likewise the (arr % 3 != 0) works for multiples of 3. These two masks are combined using & (and) and then used as mask for your arr