python - Row, column assignment without for-loop -


i wrote small script assign values numpy array knowing row , column coordinates:

gridarray = np.zeros([3,3]) gridarray_counts = np.zeros([3,3])  cols = np.random.random_integers(0,2,15) rows = np.random.random_integers(0,2,15) data = np.random.random_integers(0,9,15)  nn in np.arange(len(data)):     gridarray[rows[nn],cols[nn]] += data[nn]     gridarray_counts[rows[nn],cols[nn]] += 1

in fact, know how many values stored in same grid cell , sum of them. however, performing on arrays of lengths 100000+ getting quite slow. there way without using for-loop?

is approach similar possible? know not working yet.

gridarray[rows,cols] += data gridarray_counts[rows,cols] += 1

i use bincount this, bincount takes 1darrays you'll need write own ndbincout, like:

def ndbincount(x, weights=none, shape=none):     if shape none:         shape = x.max(1) + 1      x = np.ravel_multi_index(x, shape)     out = np.bincount(x, weights, minlength=np.prod(shape))     out.shape = shape     return out

then can do:

gridarray = np.zeros([3,3])  cols = np.random.random_integers(0,2,15) rows = np.random.random_integers(0,2,15) data = np.random.random_integers(0,9,15)  x = np.vstack([rows, cols]) temp = ndbincount(x, data, gridarray.shape) gridarray = gridarray + temp gridarray_counts = ndbincount(x, shape=gridarray.shape)

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