NAME

Chart::Colors - Perl extension to return an endless stream of new distinct RGB colours codes (good for coloring any number of chart lines)

SYNOPSIS

    #!/usr/bin/perl -w
      
    use Chart::Colors;

    my $colors = new Chart::Colors();
    my $nextcolor_hex=$colors->Next('hex');     # Get an HTML-Style answer, like F85099 (put a # in front to use in HTML, i.e. #F85099)
    my($r,$g,$b)=$colors->Next('rgb');          # Get red, green, and blue ints separately, like (255,123,88)
    my($h,$s,$v)=$colors->Next('hsv');          # Get hue, saturation, and brightness

DESCRIPTION

This module outputs an infinte sequence of visually distinct different colours.

It is useful for colorizing the lines on charts etc.

EXPORT

None by default.

Notes

new

Usage is

    my $colors = new Chart::Colors();

Next

Usage is

    my $nextcolor_hex = $colors->Next('hex');

or

    my($r,$g,$b)=$colors->Next('rgb');

hsv_to_rgb

    my($r,$g,$b)=$this->hsv_to_rgb($h,$s,$v);

AUTHOR

This module was written by Chris Drake cdrake@cpan.org, and based on https://stackoverflow.com/questions/24852345/hsv-to-rgb-color-conversion

COPYRIGHT AND LICENSE

Copyright (c) 2019 Chris Drake. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.18.2 or, at your option, any later version of Perl 5 you may have available.

    # from https://stackoverflow.com/questions/24852345/hsv-to-rgb-color-conversion
    def hsv_to_rgb(h, s, v):
        if s == 0.0: v*=255; return (v, v, v)
        i = int(h*6.) # XXX assume int() truncates!
        f = (h*6.)-i; p,q,t = int(255*(v*(1.-s))), int(255*(v*(1.-s*f))), int(255*(v*(1.-s*(1.-f)))); v*=255; i%=6
        if i == 0: return (v, t, p)
        if i == 1: return (q, v, p)
        if i == 2: return (p, v, t)
        if i == 3: return (p, q, v)
        if i == 4: return (t, p, v)
        if i == 5: return (v, p, q)

# !/usr/bin/env python3.3

from sys import argv import colorsys import itertools from fractions import Fraction

def zenos_dichotomy(): for k in itertools.count(): yield Fraction(1,2**k) # yeild is like return, except next call continues

def getfracs(): """ [Fraction(0, 1), Fraction(1, 2), Fraction(1, 4), Fraction(3, 4), Fraction(1, 8), Fraction(3, 8), Fraction(5, 8), Fraction(7, 8), Fraction(1, 16), Fraction(3, 16), ...] [0.0, 0.5, 0.25, 0.75, 0.125, 0.375, 0.625, 0.875, 0.0625, 0.1875, ...] """ yield 0 for k in zenos_dichotomy(): i = k.denominator # [1,2,4,8,16,...] for j in range(1,i,2): # start,stop,step yield Fraction(j,i)

bias = lambda x: (math.sqrt(x/3)/Fraction(2,3)+Fraction(1,3))/Fraction(6,5) # can be used for the v in hsv to map linear values 0..1 to something that looks equidistant

def genhsv(h): for s in [Fraction(6,10)]: # optionally use range for v in [Fraction(8,10),Fraction(5,10)]: # could use range too yield (h, s, v) # use bias for v here if you use range

genrgb = lambda x: colorsys.hsv_to_rgb(*x)

flatten = itertools.chain.from_iterable

gethsvs = lambda: flatten(map(genhsv,getfracs()))

getrgbs = lambda: map(genrgb, gethsvs())

def genhtml(x): uint8tuple = map(lambda y: int(y*255), x) return "{},{},{}".format(*uint8tuple)

gethtmlcolors = lambda: map(genhtml, getrgbs())

if __name__ == "__main__": print(list(itertools.islice(gethtmlcolors(), int(argv[1]))))

# print(list(itertools.islice(gethtmlcolors(), int(argv[1])))) # print(list(itertools.islice(gethtmlcolors(), 10)))

cpanm Chart::Colors

perl -MCPAN -e shell
install Chart::Colors