def hsl2rgb()

in chartify/_core/colour.py [0:0]
17 lines of code
6 McCabe index (conditional complexity)

def hsl2rgb(hsl):
    """Convert HSL representation towards RGB

    :param h: Hue, position around the chromatic circle (h=1 equiv h=0)
    :param s: Saturation, color saturation (0=full gray, 1=full color)
    :param l: Ligthness, Overhaul lightness (0=full black, 1=full white)
    :rtype: 3-uple for RGB values in float between 0 and 1

    Hue, Saturation, Range from Lightness is a float between 0 and 1

    Note that Hue can be set to any value but as it is a rotation
    around the chromatic circle, any value above 1 or below 0 can
    be expressed by a value between 0 and 1 (Note that h=0 is equiv
    to h=1).

    This algorithm came from:
    http://www.easyrgb.com/index.php?X=MATH&H=19#text19

    Here are some quick notion of HSL to RGB conversion:

    >>> from colour import hsl2rgb

    With a lightness put at 0, RGB is always rgbblack

    >>> hsl2rgb((0.0, 0.0, 0.0))
    (0.0, 0.0, 0.0)
    >>> hsl2rgb((0.5, 0.0, 0.0))
    (0.0, 0.0, 0.0)
    >>> hsl2rgb((0.5, 0.5, 0.0))
    (0.0, 0.0, 0.0)

    Same for lightness put at 1, RGB is always rgbwhite

    >>> hsl2rgb((0.0, 0.0, 1.0))
    (1.0, 1.0, 1.0)
    >>> hsl2rgb((0.5, 0.0, 1.0))
    (1.0, 1.0, 1.0)
    >>> hsl2rgb((0.5, 0.5, 1.0))
    (1.0, 1.0, 1.0)

    With saturation put at 0, the RGB should be equal to Lightness:

    >>> hsl2rgb((0.0, 0.0, 0.25))
    (0.25, 0.25, 0.25)
    >>> hsl2rgb((0.5, 0.0, 0.5))
    (0.5, 0.5, 0.5)
    >>> hsl2rgb((0.5, 0.0, 0.75))
    (0.75, 0.75, 0.75)

    With saturation put at 1, and lightness put to 0.5, we can find
    normal full red, green, blue colors:

    >>> hsl2rgb((0 , 1.0, 0.5))
    (1.0, 0.0, 0.0)
    >>> hsl2rgb((1 , 1.0, 0.5))
    (1.0, 0.0, 0.0)
    >>> hsl2rgb((1.0/3 , 1.0, 0.5))
    (0.0, 1.0, 0.0)
    >>> hsl2rgb((2.0/3 , 1.0, 0.5))
    (0.0, 0.0, 1.0)

    Of course:
    >>> hsl2rgb((0.0, 2.0, 0.5))  # doctest: +ELLIPSIS
    Traceback (most recent call last):
    ...
    ValueError: Saturation must be between 0 and 1.

    And:
    >>> hsl2rgb((0.0, 0.0, 1.5))  # doctest: +ELLIPSIS
    Traceback (most recent call last):
    ...
    ValueError: Lightness must be between 0 and 1.

    """
    hue, saturation, lightness = [float(v) for v in hsl]

    if not (0.0 - FLOAT_ERROR <= saturation <= 1.0 + FLOAT_ERROR):
        raise ValueError("Saturation must be between 0 and 1.")
    if not (0.0 - FLOAT_ERROR <= lightness <= 1.0 + FLOAT_ERROR):
        raise ValueError("Lightness must be between 0 and 1.")

    if saturation == 0:
        return lightness, lightness, lightness

    if lightness < 0.5:
        v2 = lightness * (1.0 + saturation)
    else:
        v2 = (lightness + saturation) - (saturation * lightness)

    v1 = 2.0 * lightness - v2

    r = _hue2rgb(v1, v2, hue + (1.0 / 3))
    g = _hue2rgb(v1, v2, hue)
    b = _hue2rgb(v1, v2, hue - (1.0 / 3))

    return r, g, b