from matplotlib import colors

grey_red = colors.LinearSegmentedColormap.from_list("grouping", ["lightgray", "red", "darkred"], N=128)
grey_violet = colors.LinearSegmentedColormap.from_list("grouping", ["lightgray", "mediumvioletred", "indigo"], N=128)
grey_blue = colors.LinearSegmentedColormap.from_list("grouping", ["lightgray", "cornflowerblue", "darkblue"], N=128)
