matplotlib/examples/colours.py at transforms · tecki/matplotlib · GitHub

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#!/usr/bin/env python

"""

Some simple functions to generate colours.

"""

import numpy as npy

from matplotlib.colors import colorConverter

def pastel(colour, weight=2.4):

""" Convert colour into a nice pastel shade"""

rgb = npy.asarray(colorConverter.to_rgb(colour))

# scale colour

maxc = max(rgb)

if maxc < 1.0 and maxc > 0:

# scale colour

scale = 1.0 / maxc

rgb = rgb * scale

# now decrease saturation

total = rgb.sum()

slack = 0

for x in rgb:

slack += 1.0 - x

# want to increase weight from total to weight

# pick x s.t. slack * x == weight - total

# x = (weight - total) / slack

x = (weight - total) / slack

rgb = [c + (x * (1.0-c)) for c in rgb]

return rgb

def get_colours(n):

""" Return n pastel colours. """

base = npy.asarray([[1,0,0], [0,1,0], [0,0,1]])

if n <= 3:

return base[0:n]

# how many new colours to we need to insert between

# red and green and between green and blue?

needed = (((n - 3) + 1) / 2, (n - 3) / 2)

colours = []

for start in (0, 1):

for x in npy.linspace(0, 1, needed[start]+2):

colours.append((base[start] * (1.0 - x)) +

(base[start+1] * x))

return [pastel(c) for c in colours[0:n]]

matplotlib/examples/colours.py at transforms · tecki/matplotlib · GitHub

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