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⚡️ Speed up function interp_palette by 46% #74

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⚡️ Speed up function interp_palette by 46% #74

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3 changes: 3 additions & 0 deletions src/bokeh/colors/color.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,10 @@
#-----------------------------------------------------------------------------
from __future__ import annotations

from bokeh.core.serialization import AnyRep, Serializable, Serializer

import logging # isort:skip

log = logging.getLogger(__name__)

#-----------------------------------------------------------------------------
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28 changes: 24 additions & 4 deletions src/bokeh/palettes.py
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Expand Up @@ -410,7 +410,10 @@
#-----------------------------------------------------------------------------
from __future__ import annotations

from bokeh.colors.util import RGB, NamedColor

import logging # isort:skip

log = logging.getLogger(__name__)

#-----------------------------------------------------------------------------
Expand Down Expand Up @@ -1671,9 +1674,13 @@ def interp_palette(palette: Palette, n: int) -> Palette:
r = np.interp(fractions, integers, rgba_array[:, 0]).astype(np.uint8)
g = np.interp(fractions, integers, rgba_array[:, 1]).astype(np.uint8)
b = np.interp(fractions, integers, rgba_array[:, 2]).astype(np.uint8)
# Interpolated alpha is floating-point in [0, 255]. We must scale to [0, 1] for to_hex logic.
a = np.interp(fractions, integers, rgba_array[:, 3]) / 255.0 # Remains floating-point

return tuple(RGB(*args).to_hex() for args in zip(r, g, b, a))
# Fast direct hex conversion, avoiding allocation of many RGB objects.
# Guarantee identical behavior and output types.
# Use list comprehension for maximal speed.
return tuple(rgba_to_hex(int(rr), int(gg), int(bb), float(aa)) for rr, gg, bb, aa in zip(r, g, b, a))

def magma(n: int) -> Palette:
""" Generate a palette of colors from the Magma palette.
Expand Down Expand Up @@ -1925,13 +1932,26 @@ def to_rgba_array(palette: Palette) -> npt.NDArray[np.uint8]:
""" Convert palette to a numpy array of uint8 RGBA components.
"""
rgba_array = np.empty((len(palette), 4), dtype=np.uint8)

for i, color in enumerate(palette):
palette_len = len(palette)
for i in range(palette_len):
color = palette[i]
rgba = NamedColor.from_string(color)
rgba_array[i] = (rgba.r, rgba.g, rgba.b, rgba.a*255)
rgba_array[i, 0] = rgba.r
rgba_array[i, 1] = rgba.g
rgba_array[i, 2] = rgba.b
rgba_array[i, 3] = int(rgba.a * 255)

return rgba_array


def rgba_to_hex(r: int, g: int, b: int, a: float) -> str:
# Replicates RGB.to_hex logic, avoiding per-sample object allocation.
if a < 1.0:
aa = round(a * 255)
return f"#{r:02x}{g:02x}{b:02x}{aa:02x}"
else:
return f"#{r:02x}{g:02x}{b:02x}"

#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
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