Protovis-like Color Scale for Python

from colorsys import *
import math

simple_colors = {
        "aliceblue":"f0f8ff",
        "antiquewhite":"faebd7",
        "aqua":"00ffff",
        "aquamarine":"7fffd4",
        "azure":"f0ffff",
        "beige":"f5f5dc",
        "bisque":"ffe4c4",
        "black":"000000",
        "blanchedalmond":"ffebcd",
        "blue":"0000ff",
        "blueviolet":"8a2be2",
        "brown":"a52a2a",
        "burlywood":"deb887",
        "cadetblue":"5f9ea0",
        "chartreuse":"7fff00",
        "chocolate":"d2691e",
        "coral":"ff7f50",
        "cornflowerblue":"6495ed",
        "cornsilk":"fff8dc",
        "crimson":"dc143c",
        "cyan":"00ffff",
        "darkblue":"00008b",
        "darkcyan":"008b8b",
        "darkgoldenrod":"b8860b",
        "darkgray":"a9a9a9",
        "darkgreen":"006400",
        "darkgrey":"a9a9a9",
        "darkkhaki":"bdb76b",
        "darkmagenta":"8b008b",
        "darkolivegreen":"556b2f",
        "darkorange":"ff8c00",
        "darkorchid":"9932cc",
        "darkred":"8b0000",
        "darksalmon":"e9967a",
        "darkseagreen":"8fbc8f",
        "darkslateblue":"483d8b",
        "darkslategray":"2f4f4f",
        "darkslategrey":"2f4f4f",
        "darkturquoise":"00ced1",
        "darkviolet":"9400d3",
        "deeppink":"ff1493",
        "deepskyblue":"00bfff",
        "dimgray":"696969",
        "dimgrey":"696969",
        "dodgerblue":"1e90ff",
        "firebrick":"b22222",
        "floralwhite":"fffaf0",
        "forestgreen":"228b22",
        "fuchsia":"ff00ff",
        "gainsboro":"dcdcdc",
        "ghostwhite":"f8f8ff",
        "gold":"ffd700",
        "goldenrod":"daa520",
        "gray":"808080",
        "green":"008000",
        "greenyellow":"adff2f",
        "grey":"808080",
        "honeydew":"f0fff0",
        "hotpink":"ff69b4",
        "indianred":"cd5c5c",
        "indigo":"4b0082",
        "ivory":"fffff0",
        "khaki":"f0e68c",
        "lavender":"e6e6fa",
        "lavenderblush":"fff0f5",
        "lawngreen":"7cfc00",
        "lemonchiffon":"fffacd",
        "lightblue":"add8e6",
        "lightcoral":"f08080",
        "lightcyan":"e0ffff",
        "lightgoldenrodyellow":"fafad2",
        "lightgray":"d3d3d3",
        "lightgreen":"90ee90",
        "lightgrey":"d3d3d3",
        "lightpink":"ffb6c1",
        "lightsalmon":"ffa07a",
        "lightseagreen":"20b2aa",
        "lightskyblue":"87cefa",
        "lightslategray":"778899",
        "lightslategrey":"778899",
        "lightsteelblue":"b0c4de",
        "lightyellow":"ffffe0",
        "lime":"00ff00",
        "limegreen":"32cd32",
        "linen":"faf0e6",
        "magenta":"ff00ff",
        "maroon":"800000",
        "mediumaquamarine":"66cdaa",
        "mediumblue":"0000cd",
        "mediumorchid":"ba55d3",
        "mediumpurple":"9370db",
        "mediumseagreen":"3cb371",
        "mediumslateblue":"7b68ee",
        "mediumspringgreen":"00fa9a",
        "mediumturquoise":"48d1cc",
        "mediumvioletred":"c71585",
        "midnightblue":"191970",
        "mintcream":"f5fffa",
        "mistyrose":"ffe4e1",
        "moccasin":"ffe4b5",
        "navajowhite":"ffdead",
        "navy":"000080",
        "oldlace":"fdf5e6",
        "olive":"808000",
        "olivedrab":"6b8e23",
        "orange":"ffa500",
        "orangered":"ff4500",
        "orchid":"da70d6",
        "palegoldenrod":"eee8aa",
        "palegreen":"98fb98",
        "paleturquoise":"afeeee",
        "palevioletred":"db7093",
        "papayawhip":"ffefd5",
        "peachpuff":"ffdab9",
        "peru":"cd853f",
        "pink":"ffc0cb",
        "plum":"dda0dd",
        "powderblue":"b0e0e6",
        "purple":"800080",
        "red":"ff0000",
        "rosybrown":"bc8f8f",
        "royalblue":"4169e1",
        "saddlebrown":"8b4513",
        "salmon":"fa8072",
        "sandybrown":"f4a460",
        "seagreen":"2e8b57",
        "seashell":"fff5ee",
        "sienna":"a0522d",
        "silver":"c0c0c0",
        "skyblue":"87ceeb",
        "slateblue":"6a5acd",
        "slategray":"708090",
        "slategrey":"708090",
        "snow":"fffafa",
        "springgreen":"00ff7f",
        "steelblue":"4682b4",
        "tan":"d2b48c",
        "teal":"008080",
        "thistle":"d8bfd8",
        "tomato":"ff6347",
        "turquoise":"40e0d0",
        "violet":"ee82ee",
        "wheat":"f5deb3",
        "white":"ffffff",
        "whitesmoke":"f5f5f5",
        "yellow":"ffff00",
        "yellowgreen":"9acd32"
    }

class ColorScale:
    def __init__(self, min, max):
        self.min = float(min)
        self.max = float(max)

    def range(self, color1, color2):
        def HSV(color):
            color_hex = simple_colors[color]
            colorlist = [float(int(color_hex[i:i+2], 16))/255. \
                for i in range(0, len(color_hex), 2)]
            return rgb_to_hsv(*colorlist)
        def evaluate(value):
            scale = (float(value) - self.min)/(self.max - self.min)
            c1 = HSV(color1)
            c2 = HSV(color2)
            if c2[0] > c1[0]:
                if (c2[0] - c1[0]) > 0.5:
                    h = c1[0] - scale*(1.-c2[0]+c1[0])
                    if h < 0.0:
                        h += 1.0
                else:
                    h = c1[0] + scale*(c2[0]-c1[0])
            else:
                if (c1[0] - c2[0]) > 0.5:
                    h = c1[0] + scale*(1.-c1[0]+c2[0])
                    if h > 1.0:
                        h -= 1.0
                else:
                    h = c1[0] - scale*(c1[0]-c2[0])
            s = c1[1]+(c2[1]-c1[1])*scale
            v = c1[2]+(c2[2]-c1[2])*scale
            return tuple(map(lambda x: 255.*x, hsv_to_rgb(h, s, v)))
        return lambda y: '%02x%02x%02x' % evaluate(y)