Numpy 直方图二维向量

Question

I have a list of xy like the picture above

in code it works like this:

np.array([[1.3,2.1],[1.5,2.2],[3.1,4.8]])

now I would like to set a grid of which I can set the start, the number of columns and rows as well as the row and columns size, and then count the number of points in each cell.

in this example [0,0] has 1 point in it, [1,0] has 1, [2,0] has 3, [0,1] has 4 and so on.

I know it would probably be trivial to do by hand, even without numpy, but I need to create it as fast as possible, since I will have to process a ton of data this way.

whats a good way to do this? Basicly create a 2D Histogramm of points? And more importantly, how can I do it as fast as possible?

Answer 1

I think numpy.histogram2d is the best option.

a = np.array([[1.3,2.1],[1.5,2.2],[3.1,4.8]])
H, _, _ = np.histogram2d(a[:, 0], a[:, 1], bins=(range(6), range(6)))
print(H)
# [[0. 0. 0. 0. 0.]
#  [0. 0. 2. 0. 0.]
#  [0. 0. 0. 0. 0.]
#  [0. 0. 0. 0. 1.]
#  [0. 0. 0. 0. 0.]]