ribs.visualize.grid_archive_heatmap

ribs.visualize.grid_archive_heatmap(archive, ax=None, *, transpose_measures=False, cmap='magma', aspect=None, vmin=None, vmax=None, cbar='auto', pcm_kwargs=None, cbar_kwargs=None)

Plots heatmap of a GridArchive with 1D or 2D measure space.

This function creates a grid of cells and shades each cell with a color corresponding to the objective value of that cell’s elite. This function uses pcolormesh() to generate the grid. For further customization, pass extra kwargs to pcolormesh() through the pcm_kwargs parameter. For instance, to create black boundaries of width 0.1, pass in pcm_kwargs={"edgecolor": "black", "linewidth": 0.1}.

Examples

>>> import numpy as np
>>> import matplotlib.pyplot as plt
>>> from ribs.archives import GridArchive
>>> from ribs.visualize import grid_archive_heatmap
>>> # Populate the archive with the negative sphere function.
>>> archive = GridArchive(solution_dim=2,
...                       dims=[20, 20],
...                       ranges=[(-1, 1), (-1, 1)])
>>> x = y = np.linspace(-1, 1, 100)
>>> xxs, yys = np.meshgrid(x, y)
>>> xxs, yys = xxs.flatten(), yys.flatten()
>>> archive.add(solution_batch=np.stack((xxs, yys), axis=1),
...             objective_batch=-(xxs**2 + yys**2),
...             measures_batch=np.stack((xxs, yys), axis=1))
>>> # Plot a heatmap of the archive.
>>> plt.figure(figsize=(8, 6))
>>> grid_archive_heatmap(archive)
>>> plt.title("Negative sphere function")
>>> plt.xlabel("x coords")
>>> plt.ylabel("y coords")
>>> plt.show()

Parameters

• archive (GridArchive) – A 2D GridArchive.

• ax (matplotlib.axes.Axes) – Axes on which to plot the heatmap. If None, the current axis will be used.

• transpose_measures (bool) – By default, the first measure in the archive will appear along the x-axis, and the second will be along the y-axis. To switch this behavior (i.e. to transpose the axes), set this to True.

• cmap (str, list, matplotlib.colors.Colormap) – The colormap to use when plotting intensity. Either the name of a Colormap, a list of RGB or RGBA colors (i.e. an \(N \times 3\) or \(N \times 4\) array), or a Colormap object.

• aspect ('auto', 'equal', float) – The aspect ratio of the heatmap (i.e. height/width). Defaults to 'auto' for 2D and 0.5 for 1D. 'equal' is the same as aspect=1.

• vmin (float) – Minimum objective value to use in the plot. If None, the minimum objective value in the archive is used.

• vmax (float) – Maximum objective value to use in the plot. If None, the maximum objective value in the archive is used.

• cbar ('auto', None, matplotlib.axes.Axes) – By default, this is set to 'auto' which displays the colorbar on the archive’s current Axes. If None, then colorbar is not displayed. If this is an Axes, displays the colorbar on the specified Axes.

• pcm_kwargs (dict) – Additional kwargs to pass to pcolormesh().

• cbar_kwargs (dict) – Additional kwargs to pass to colorbar().

Raises

ValueError – The archive’s dimension must be 1D or 2D.