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⚡️ Speed up function gray by 39% #80

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⚡️ Speed up function gray by 39% #80

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22 changes: 14 additions & 8 deletions src/bokeh/palettes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -412,13 +412,6 @@

import logging # isort:skip
log = logging.getLogger(__name__)

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

# Standard library imports
import math
from copy import deepcopy
from typing import TYPE_CHECKING, TypeAlias

Expand Down Expand Up @@ -1526,7 +1519,7 @@ def linear_palette(palette: Palette, n: int) -> Palette:
"""
if n > len(palette):
raise ValueError(f"Requested {n} colors, function can only return colors up to the base palette's length ({len(palette)})")
return tuple( palette[math.floor(i)] for i in np.linspace(0, len(palette)-1, num=n) )
return _linear_palette_fast(palette, n)

def diverging_palette(palette1: Palette, palette2: Palette, n: int, midpoint: float = 0.5) -> Palette:
""" Generate a new palette by combining exactly two input palettes.
Expand Down Expand Up @@ -1932,6 +1925,19 @@ def to_rgba_array(palette: Palette) -> npt.NDArray[np.uint8]:

return rgba_array


def _linear_palette_fast(palette: Palette, n: int) -> Palette:
"""Optimized subset extraction using precomputed indices."""
# Use numpy to compute indices, cast to int only once, avoid math.floor
palette_len = len(palette)
if n == palette_len:
return palette
indices = np.linspace(0, palette_len-1, num=n)
# Unlike math.floor, numpy implicitly casts to float, so need int conversion.
idx = indices.astype(int)
# Using list comprehension is fast for short lookups, but tuple is required as output.
return tuple(palette[i] for i in idx)

#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
Expand Down