other:python:misc_by_jyp
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other:python:misc_by_jyp [2022/05/23 15:36] jypeter [numpy related stuff] Added the "variable number of indices" section |
other:python:misc_by_jyp [2022/05/23 16:01] jypeter [numpy related stuff] Changed the VIEW update warnng example |
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| Line 291: | Line 291: | ||
| (4, 10) | (4, 10) | ||
| - | >>> # WARNING! WARNING! A slice is a VIEW and NOT A COPY | + | >>> # WARNING! DANGERRRR! NEVER forget that a VIEW is NOT A COPY |
| - | >>> i10[my_fancy_slices] = -1 | + | >>> # and that you can change the content of the original array by mistake |
| + | >>> my_view = i10[my_slices] | ||
| + | >>> my_view[:, :] = -1 | ||
| + | >>> my_view | ||
| + | array([[-1., -1.], | ||
| + | [-1., -1.], | ||
| + | [-1., -1.], | ||
| + | [-1., -1.]]) | ||
| >>> i10 | >>> i10 | ||
| array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.], | array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.], | ||
| [ 0., 1., 0., 0., 0., 0., 0., 0., 0., 0.], | [ 0., 1., 0., 0., 0., 0., 0., 0., 0., 0.], | ||
| [ 0., 0., 1., 0., 0., 0., 0., 0., 0., 0.], | [ 0., 0., 1., 0., 0., 0., 0., 0., 0., 0.], | ||
| - | [-1., -1., -1., -1., -1., -1., -1., -1., -1., -1.], | + | [ 0., 0., 0., 1., -1., -1., 0., 0., 0., 0.], |
| - | [-1., -1., -1., -1., -1., -1., -1., -1., -1., -1.], | + | [ 0., 0., 0., 0., -1., -1., 0., 0., 0., 0.], |
| - | [-1., -1., -1., -1., -1., -1., -1., -1., -1., -1.], | + | [ 0., 0., 0., 0., -1., -1., 0., 0., 0., 0.], |
| - | [-1., -1., -1., -1., -1., -1., -1., -1., -1., -1.], | + | [ 0., 0., 0., 0., -1., -1., 1., 0., 0., 0.], |
| [ 0., 0., 0., 0., 0., 0., 0., 1., 0., 0.], | [ 0., 0., 0., 0., 0., 0., 0., 1., 0., 0.], | ||
| [ 0., 0., 0., 0., 0., 0., 0., 0., 1., 0.], | [ 0., 0., 0., 0., 0., 0., 0., 0., 1., 0.], | ||
| - | [ 0., 0., 0., 0., 0., 0., 0., 0., 0., 1.]]) | + | [ 0., 0., 0., 0., 0., 0., 0., 0., 0., 1.]])</code> |
| - | </code> | + | |
| === Finding and counting unique values === | === Finding and counting unique values === | ||
other/python/misc_by_jyp.txt · Last modified: 2024/04/19 12:02 by jypeter
