| import numpy as np | |
| def longest_common_prefix(xs, ys): | |
| min_len = min(len(xs), len(ys)) | |
| idxs = (xs[:min_len] != ys[:min_len]).nonzero()[0] | |
| if len(idxs) > 0: | |
| return idxs[0] | |
| else: | |
| return min_len | |
| # Like np.cumsum, but with a leading zero. | |
| def cumsum0(x, axis): | |
| pad_width = len(x.shape) * [(0,0)] | |
| pad_width[axis] = (1,0) | |
| return np.cumsum(np.pad(x, pad_width), axis=axis) |