Python matplotlib.colors 模块，to_hex() 实例源码

def hue_map(self, value):
        '''
        :param value: number 0 to 1, map to hue 0.6 - 0 (blue to red, like heatmap)
                      more highter the value, more warm the color
        :return: hex of rgb
        '''
        HUE_MAX = 0.6
        hue = pow(1 - value, 2) * HUE_MAX
        rgb = colors.hsv_to_rgb((hue, 1, 1))
        hex = colors.to_hex(rgb)
        return hex

def swap_colors(json_file_path):
    '''
    Switches out color ramp in meta.json files.
    Uses custom color ramp if provided and valid; otherwise falls back to nextstrain default colors.
    N.B.: Modifies json in place and writes to original file path.
    '''
    j = json.load(open(json_file_path, 'r'))
    color_options = j['color_options']

    for k,v in color_options.items():
        if 'color_map' in v:
            categories, colors = zip(*v['color_map'])

            ## Use custom colors if provided AND present for all categories in the dataset
            if custom_colors and all([category in custom_colors for category in categories]):
                colors = [ custom_colors[category] for category in categories ]

            ## Expand the color palette if we have too many categories
            elif len(categories) > len(default_colors):
                from matplotlib.colors import LinearSegmentedColormap, to_hex
                from numpy import linspace
                expanded_cmap = LinearSegmentedColormap.from_list('expanded_cmap', default_colors[-1], N=len(categories))
                discrete_colors = [expanded_cmap(i) for i in linspace(0,1,len(categories))]
                colors = [to_hex(c).upper() for c in discrete_colors]

            else: ## Falls back to default nextstrain colors
                colors = default_colors[len(categories)] # based on how many categories are present; keeps original ordering

            j['color_options'][k]['color_map'] = map(list, zip(categories, colors))

    json.dump(j, open(json_file_path, 'w'), indent=1)