Find the row indexes of several values in a numpy array

Question

I have an array X:

X = np.array([[4,  2],
              [9,  3],
              [8,  5],
              [3,  3],
              [5,  6]])

And

Answer 1

Another alternative is to use asvoid (below) to view each row as a single value of void dtype. This reduces a 2D array to a 1D array, thus allowing you to use np.in1d as usual:

import numpy as np

def asvoid(arr):
    """
    Based on http://stackoverflow.com/a/16973510/190597 (Jaime, 2013-06)
    View the array as dtype np.void (bytes). The items along the last axis are
    viewed as one value. This allows comparisons to be performed which treat
    entire rows as one value.
    """
    arr = np.ascontiguousarray(arr)
    if np.issubdtype(arr.dtype, np.floating):
        """ Care needs to be taken here since
        np.array([-0.]).view(np.void) != np.array([0.]).view(np.void)
        Adding 0. converts -0. to 0.
        """
        arr += 0.
    return arr.view(np.dtype((np.void, arr.dtype.itemsize * arr.shape[-1])))

X = np.array([[4,  2],
              [9,  3],
              [8,  5],
              [3,  3],
              [5,  6]])

searched_values = np.array([[4, 2],
                            [3, 3],
                            [5, 6]])

idx = np.flatnonzero(np.in1d(asvoid(X), asvoid(searched_values)))
print(idx)
# [0 3 4]