ppo.py 文件源码

def _colorline(ax, x, y, color = (0, 0, 0), **kwargs):
    '''
    Plots the curve `y(x)` with linearly increasing alpha.
    Adapted from `http://nbviewer.jupyter.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb`_.

    '''

    # A bit hacky... But there doesn't seem to be
    # an easy way to get the hex code for a named color...
    if isinstance(color, string_types):
        if color.startswith("#"):
            hex = color[1:]
        else:
            if len(color) == 1:
                if color == 'k':
                    color = 'black'
                elif color == 'r':
                    color = 'red'
                elif color == 'b':
                    color = 'blue'
                elif color == 'g':
                    color = 'green'
                elif color == 'y':
                    color = 'yellow'
                elif color == 'w':
                    color = 'white'
                else:
                    # ?!
                    color = 'black'
            hex = matplotlib.colors.cnames[color.lower()][1:]
        r, g, b = tuple(int(hex[i:i+2], 16) / 255. for i in (0, 2, 4))
    else:
        r, g, b = color

    colors = [(r, g, b, i) for i in np.linspace(0, 1, 3)]
    cmap = LinearSegmentedColormap.from_list('alphacmap', colors, N = 1000)
    points = np.array([x, y]).T.reshape(-1, 1, 2)
    segments = np.concatenate([points[:-1], points[1:]], axis=1)
    lc = LineCollection(segments, array = np.linspace(0.0, 1.0, len(x)),
                        cmap = cmap, norm = pl.Normalize(0.0, 1.0), **kwargs)
    ax.add_collection(lc)

    return lc