Given you have rows and cols coordinates/indexes, how can I update multiple cells simultaneously... something like :
rows_idxs = [.....]
cols_idxs = [.....]
ary[rows_idxs, cols_idxs] += 1
OR
ary[itertools.product(rows_idxs,cols_idxs)] += 1
neither of those works !?
How can I do that ?
If you know your row and col indices have no duplicate values then the numpy replacement for itertools.product would be np.ix_. Be sure to note the trailing underline.
For example:
a = np.arange(15).reshape(3,5)
a[np.ix_([0,2],[1,3,4])] += 1
a
# array([[ 0, 2, 2, 4, 5],
# [ 5, 6, 7, 8, 9],
# [10, 12, 12, 14, 15]])
If there are duplicates you can use it together with np.add.at:
For example:
a = np.arange(15).reshape(3,5)
np.add.at(a,np.ix_([0,0,0,2],[0,0,3,4,4]),1)
a
# array([[ 6, 1, 2, 6, 10],
# [ 5, 6, 7, 8, 9],
# [12, 11, 12, 14, 16]])
