Is there any way to use bivariate colormaps in matplotlib?

by

imshow can take an array of [r, g, b] entries. So you can convert the absolute values to intensities and phases – to hues.

I will use as an example complex numbers, because for it it makes the most sense. If needed, you can always add numpy arrays Z = X + 1j * Y.

So for your data Z you can use e.g.

imshow(complex_array_to_rgb(Z))

where (EDIT: made it quicker and nicer thanks to this suggestion)

def complex_array_to_rgb(X, theme="dark", rmax=None):
    '''Takes an array of complex number and converts it to an array of [r, g, b],
    where phase gives hue and saturaton/value are given by the absolute value.
    Especially for use with imshow for complex plots.'''
    absmax = rmax or np.abs(X).max()
    Y = np.zeros(X.shape + (3,), dtype="float")
    Y[..., 0] = np.angle(X) / (2 * pi) % 1
    if theme == 'light':
        Y[..., 1] = np.clip(np.abs(X) / absmax, 0, 1)
        Y[..., 2] = 1
    elif theme == 'dark':
        Y[..., 1] = 1
        Y[..., 2] = np.clip(np.abs(X) / absmax, 0, 1)
    Y = matplotlib.colors.hsv_to_rgb(Y)
    return Y

So, for example:

Z = np.array([[3*(x + 1j*y)**3 + 1/(x + 1j*y)**2
              for x in arange(-1,1,0.05)] for y in arange(-1,1,0.05)])
imshow(complex_array_to_rgb(Z, rmax=5), extent=(-1,1,-1,1))

enter image description here

imshow(complex_array_to_rgb(Z, rmax=5, theme="light"), extent=(-1,1,-1,1))

enter image description here

More Related Contents:

  1. Heatmap with text in each cell with matplotlib’s pyplot
  2. Generate a heatmap in MatPlotLib using a scatter data set
  3. pyplot – copy an axes content and show it in a new figure
  4. Heatmap in matplotlib with pcolor?
  5. matplotlib strings as labels on x axis
  6. Embedding small plots inside subplots in matplotlib
  7. Annotate data points while plotting from Pandas DataFrame
  8. How to pick a new color for each plotted line within a figure in matplotlib?
  9. Matplotlib: setting x-limits also forces tick labels?
  10. Pyplot sorting y-values automatically
  11. Rotate label text in seaborn factorplot
  12. Matplotlib: Changing the color of an axis
  13. Creating figure with exact size and no padding (and legend outside the axes)
  14. Matplotlib axis with two scales shared origin
  15. vertical & horizontal lines in matplotlib
  16. How to set default colormap in Matplotlib
  17. Matplotlib Colormap with two parameter
  18. Generate a heatmap using a scatter data set
  19. How do I include a matplotlib Figure object as subplot? [duplicate]
  20. Rotating axis text for each subplot
  21. matplotlib savefig in jpeg format
  22. Plotting lines connecting points
  23. How to express classes on the axis of a heatmap in Seaborn
  24. disable matplotlib toolbar
  25. Matplotlib – sequence is off when using plt.imshow()
  26. Python package to plot two heatmaps in one (split each square into two triangles)
  27. How to change font size of the scientific notation in matplotlib?
  28. Getting xkcd plots using matplotlib
  29. Overlapping yticklabels: Is it possible to control cell size of heatmap in seaborn?
  30. First and last row cut in half of heatmap plot

Leave a Comment