distinct_colours.py

# -*- coding: iso-8859-1 -*-

"""
Colour-blind proof distinct colours module, based on work by Paul Tol
Pieter van der Meer, 2011
SRON - Netherlands Institute for Space Research
"""

# colour table in HTML hex format
hexcols = ['#332288', '#88CCEE', '#44AA99', '#117733', '#999933', '#DDCC77', 
           '#CC6677', '#882255', '#AA4499', '#661100', '#6699CC', '#AA4466',
           '#4477AA']

greysafecols = ['#809BC8', '#FF6666', '#FFCC66', '#64C204']

xarr = [[12], 
        [12, 6], 
        [12, 6, 5], 
        [12, 6, 5, 3], 
        [0, 1, 3, 5, 6], 
        [0, 1, 3, 5, 6, 8], 
        [0, 1, 2, 3, 5, 6, 8], 
        [0, 1, 2, 3, 4, 5, 6, 8], 
        [0, 1, 2, 3, 4, 5, 6, 7, 8], 
        [0, 1, 2, 3, 4, 5, 9, 6, 7, 8], 
        [0, 10, 1, 2, 3, 4, 5, 9, 6, 7, 8], 
        [0, 10, 1, 2, 3, 4, 5, 9, 6, 11, 7, 8]]

# get specified nr of distinct colours in HTML hex format.
# in: nr - number of colours [1..12]
# returns: list of distinct colours in HTML hex

def get_distinct(nr):

    # check if nr is in correct range
    
    if nr < 1 or nr > 12:
        print("wrong nr of distinct colours!")
        return

    # get list of indices
    
    lst = xarr[nr-1]
    
    # generate colour list by stepping through indices and looking them up
    # in the colour table

    i_col = 0
    col = [0] * nr
    for idx in lst:
        col[i_col] = hexcols[idx]
        i_col+=1
    return col

# gets 4 colours, which also look distinct in black&white
# returns: list of 4 colours in 
#def get_distinct_grey():

import sys

# display usage information and produce example plot.
if __name__ == '__main__':
    import numpy as np
    import matplotlib.mlab as mlab
    import matplotlib.pyplot as plt

    print(__doc__)
    print("usage examples: ")
    print("print distinct_colours.get_distinct(2)")
    print(get_distinct(2))
    print("print distinct_colours.greysafecols")
    print(greysafecols)

    print("generating example plot: distinct_colours_example.png")
    plt.close()
    t = np.arange(0.0, 2.0, 0.01)
    n = 12
    if len(sys.argv) > 1: n = int(sys.argv[1])
    cols = get_distinct(n)
    d = 2./n
    for i in range(n):
        s = np.sin(i*d*np.pi*t)
        plt.plot(t, s, linewidth=2.0, c=cols[i], label=str(i))

    plt.xlabel('time (s)')
    plt.ylabel('voltage (mV)')
    plt.title('Distinct colours example (n = '+str(n)+')')
    plt.grid(True)
    plt.legend(loc=3, ncol=2)
    
    plt.savefig("distinct_colours_example.png")
    plt.show()