David, that doesn’t work, because np.cumsum(mask)[mask] is always equal to np.arange(mask.sum()) + 1. Robert’s answer is correct. Eric On Sat, 21 Oct 2017 at 13:12 Daπid <davidmenhur@gmail.com> wrote: On 21 October 2017 at 21:03, Robert Kern <robert.kern@gmail.com> wrote:
Index with a boolean mask.
mask = (tmp_px > 2) px = tmp_px[mask] py = tmp_py[mask] # ... etc.
That isn't equivalent, note that j only increases when tmp_px > 2. I think you can do it with something like:
mask = tmp_px > 2 j_values = np.cumsum(mask)[mask] i_values = np.arange(len(j_values))
px[i_values] = tmp_i[j_values]
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