Source code for photutils.utils.colormaps

# Licensed under a 3-clause BSD style license - see LICENSE.rst
This module provides tools for generating matplotlib colormaps.

import numpy as np

__all__ = ['make_random_cmap']

[docs] def make_random_cmap(ncolors=256, seed=None): """ Make a matplotlib colormap consisting of (random) muted colors. A random colormap is very useful for plotting segmentation images. Parameters ---------- ncolors : int, optional The number of colors in the colormap. The default is 256. seed : int, optional A seed to initialize the `numpy.random.BitGenerator`. If `None`, then fresh, unpredictable entropy will be pulled from the OS. Separate function calls with the same ``seed`` will generate the same colormap. Returns ------- cmap : `matplotlib.colors.ListedColormap` The matplotlib colormap with random colors in RGBA format. """ from matplotlib import colors rng = np.random.default_rng(seed) hue = rng.uniform(low=0.0, high=1.0, size=ncolors) sat = rng.uniform(low=0.2, high=0.7, size=ncolors) val = rng.uniform(low=0.5, high=1.0, size=ncolors) hsv = np.dstack((hue, sat, val)) rgb = np.squeeze(colors.hsv_to_rgb(hsv)) return colors.ListedColormap(colors.to_rgba_array(rgb))