python - Is it possible to get color gradients under curve in matplotlib? -

i happened see beautiful graphs on page shown below:

is possible such color gradients in matplotlib?

there have been handful of previous answers similar questions (e.g. https://stackoverflow.com/a/22081678/325565), recommend sub-optimal approach.

most of previous answers recommend plotting white polygon on pcolormesh fill. less ideal 2 reasons:

1. the background of axes can't transparent, there's filled polygon overlying it
2. pcolormesh slow draw , isn't smoothly interpolated.

it's touch more work, there's method draws faster , gives better visual result: set clip path of image plotted imshow.

as example:

import numpy np import matplotlib.pyplot plt import matplotlib.colors mcolors matplotlib.patches import polygon np.random.seed(1977)  def main():     _ in range(5):         gradient_fill(*generate_data(100))     plt.show()  def generate_data(num):     x = np.linspace(0, 100, num)     y = np.random.normal(0, 1, num).cumsum()     return x, y  def gradient_fill(x, y, fill_color=none, ax=none, **kwargs):     """     plot line linear alpha gradient filled beneath it.      parameters     ----------     x, y : array-like         data values of line.     fill_color : matplotlib color specifier (string, tuple) or none         color fill. if none, color of line used.     ax : matplotlib axes instance         axes plot on. if none, current pyplot axes used.     additional arguments passed on matplotlib's ``plot`` function.      returns     -------     line : line2d instance         line plotted.     im : axesimage instance         transparent gradient clipped area beneath curve.     """     if ax none:         ax = plt.gca()      line, = ax.plot(x, y, **kwargs)     if fill_color none:         fill_color = line.get_color()      zorder = line.get_zorder()     alpha = line.get_alpha()     alpha = 1.0 if alpha none else alpha      z = np.empty((100, 1, 4), dtype=float)     rgb = mcolors.colorconverter.to_rgb(fill_color)     z[:,:,:3] = rgb     z[:,:,-1] = np.linspace(0, alpha, 100)[:,none]      xmin, xmax, ymin, ymax = x.min(), x.max(), y.min(), y.max()     im = ax.imshow(z, aspect='auto', extent=[xmin, xmax, ymin, ymax],                    origin='lower', zorder=zorder)      xy = np.column_stack([x, y])     xy = np.vstack([[xmin, ymin], xy, [xmax, ymin], [xmin, ymin]])     clip_path = polygon(xy, facecolor='none', edgecolor='none', closed=true)     ax.add_patch(clip_path)     im.set_clip_path(clip_path)      ax.autoscale(true)     return line, im  main()