Find index of a vector inside a matrix in Python

Question

Given a matrix ( numpy array) A and a vector v .

A = np.array([[5,0],[1,-2],[0,2],[-1,3],[1,2]])
v = np.array([0,2])

What is the best way to get the index of the vector v in the matrix A (in this case one should get 2).

Answer 1

这样做：

np.argwhere((v == A).all(1))

Out[82]: array([[2]], dtype=int64)

Answer 2

If by best you mean fastest , after thorough experimentation user hpaulj pointed out that np.flatnonzero is a much faster alternative to np.argwhere . You can use it this way:

np.flatnonzero((v==A).all(1))[0]

Output:

2