9.6  Colormap Utilities

colorbar

The colorbar function (also available as cmap for MATLAB compatibility) provides a simple way to add a colorbar to a plot created with mechanicskit.patch.

A key feature of this function is that when called without arguments, it automatically retrieves the colormap and data limits from the most recent patch plot, eliminating the need to manually create and configure a ScalarMappable.

Signature:

def colorbar(cmap=None, limits=None, clims=None, 
             ax=None, label=None, ticks=None, 
             orientation='vertical', **kwargs)

Key Parameters:

• cmap (str, optional): The name of the colormap. If None, it’s retrieved from the last patch call.
• limits or clims (tuple, optional): The (vmin, vmax) limits for the color data. If None, they are retrieved from the last patch call or inferred from the data.
• ax (matplotlib.axes.Axes, optional): The axes to associate the colorbar with.
• label (str, optional): A text label for the colorbar.
• ticks (array-like, optional): Specific tick locations for the colorbar.
• orientation (str, optional): 'vertical' (default) or 'horizontal'.

Automatic Mode (Most Common Usage):

The simplest way to use colorbar is to call it directly after patch.

import numpy as np
import mechanicskit as mk
import matplotlib.pyplot as plt

# Mesh data
P = np.array([[0, 0], [1, 0], [0.5, 0.866]])
elements = np.array([[1, 2], [2, 3], [3, 1]])
forces = np.array([100, -50, 75])

# Create the plot
fig, ax = plt.subplots()
mk.patch(Faces=elements, Vertices=P, CData=forces, cmap='coolwarm')

# Add the colorbar automatically
mk.colorbar(label="Element Force (N)")

plt.show()

Discrete vs. Continuous Colorbars:

The colorbar function is intelligent enough to create the correct type of colorbar based on the patch call:

• If patch was used with FaceColor='flat' (for per-element data), colorbar will create a discrete colorbar with distinct color bands.
• If patch was used with FaceColor='interp' (for per-vertex data), colorbar will create a continuous, smooth gradient colorbar.