Speedup LinearSegmentedColormap.from_list. #19287
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lib/matplotlib/colors.py
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| @@ -362,10 +362,16 @@ def to_rgba_array(c, alpha=None): | |||
| if len(c) == 0: | |||
| return np.zeros((0, 4), float) | |||
| else: | |||
| if np.iterable(alpha): | |||
| return np.array([to_rgba(cc, aa) for cc, aa in zip(c, alpha)]) | |||
| lens = {len(cc) if isinstance(cc, (list, tuple)) else -1 for cc in c} | |||
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What if one of them is already a NumPy array? I guess it will just take the slow path, then?
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Yes it will, but that's quite artificial. Users would have to provide something like
[np.array(r1, g1, b1),
np.array(r2, g2, b2),
...
]
@anntzer This should get a comment explaining that all branches do the same and the distinction is for performance optimization.
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I don't know if I'd consider artificial necessarily. If someone called to_rgba_array (perhaps indirectly via a getter on some artist) and then passed individual colours from it, then it could be an array.
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Fair enough, OTOH adding np.ndarray to the tuple of instances checked would complicate the code a bit as you can't necessarily call len on a ndarray (it may be zero-dim). There's actually a test that exercises that case...
For now I guess falling back on the slow path is just fine for that case.
... by special-casing lists-of-rgb(a) tuples in to_rgba_array. This speeds up colorcet's import nearly twofold, from ~430ms to ~250ms on my machine. (colorcet generates a lot of colormaps at import time.)
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@QuLogic is there a reason you did not merge after the second positive review? |
|
CI fixes had not been confirmed at the time. |
... by special-casing lists-of-rgb(a) tuples in to_rgba_array.
This speeds up colorcet's import nearly twofold, from ~430ms to ~250ms
on my machine. (colorcet generates a lot of colormaps at import time.)
PR Summary
PR Checklist
pytestpasses).flake8on changed files to check).flake8-docstringsand runflake8 --docstring-convention=all).doc/users/next_whats_new/(follow instructions in README.rst there).doc/api/next_api_changes/(follow instructions in README.rst there).