python - Numpy Summation for Index in Boolean Array -

In the figure, I have a boolean array of the same length of the matrix. I want to calculate the matrix elements which correspond to the boolean array. How do i do this

  a: [true, false, true] b: [[1,1,1], [2,2,2], [3,3,3]]]  

Say that the elements of the sub array were to be composed

Index is 0 true : Thus I start at 3 summaries (zero

The index is 1 incorrect : Thus the conference stays at 3

The index is 2 true : Thus I Adds the inclusion from 12 to 12

How can I do this (Boolean and part of the equation; I will call each individual sub array Do not need to add)?

You can just type your Boolean array a to b , Then the resultant (2, 3) take the sum of the array: np a = np.array ([true, false, true]) b = np. Array (# [1,1,1], [2,2,2], [3,3,3]] # index rows of B where one is true (the first and third, the line of B) print (b [ A]) # [[1 1 1] # [3 3 3] # Impress printing on all the elements in these lines (B [A]. (SUM)) # 12

It seems that you will benefit from reading.