Advanced color editing for Matplotlib and Seaborn

colormap_editor.py

import colorsys
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
%matplotlib inline

def alter(alist, col, factor=1.1):
    tmp = np.array(alist)
    tmp[:,col] = tmp[:,col] * factor
    tmp[tmp > 1] = 1
    tmp[tmp < 0] = 0
    
    new = []
    for row in tmp.tolist():
        new.append(tuple(row))
        
    return new
    

def rgb2hls(alist):
    alist = alist[:]
    for i, row in enumerate(alist):
        hls = colorsys.rgb_to_hls(row[0], row[1], row[2])
        alist[i] = hls
    return alist


def hls2rgb(alist):
    alist = alist[:]
    for i, row in enumerate(alist):
        hls = colorsys.hls_to_rgb(row[0], row[1], row[2])
        alist[i] = hls
    return alist


def lighten(alist, increase=0.2):
    factor = 1 + increase
    hls = rgb2hls(alist)
    new = alter(hls, 1, factor=factor)
    rgb = hls2rgb(new)
    return rgb


def darken(alist, decrease=0.2):
    factor = 1 - decrease
    hls = rgb2hls(alist)
    new = alter(hls, 1, factor=factor)
    rgb = hls2rgb(new)
    return rgb


def saturate(alist, increase=0.2):
    factor = 1 + increase
    hls = rgb2hls(alist)
    new = alter(hls, 2, factor=factor)
    rgb = hls2rgb(new)
    return rgb
    

def desaturate(alist, decrease=0.2):
    factor = 1 - decrease
    hls = rgb2hls(alist)
    new = alter(hls, 2, factor=factor)
    rgb = hls2rgb(new)
    return rgb

#Visual examples
copal = sns.color_palette("hls", 7)

sns.palplot(copal)
sns.palplot(lighten(copal))
sns.palplot(darken(copal))
sns.palplot(saturate(copal))
sns.palplot(desaturate(copal))

Creating custom colormaps has been made much easier with Seaborn, but it still lacks the ability to customize the colormaps at finer granularity, e.g., saturation and light levels. This is some code that I wrote up to allow quick editing of the color maps to get just what you want.