matplotlib.pyplot.pcolormesh() in Python

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. Pyplot is a state-based interface to a Matplotlib module which provides a MATLAB-like interface.

matplotlib.pyplot.pcolormesh() Function:

The pcolormesh() function in pyplot module of matplotlib library is used to create a pseudocolor plot with a non-regular rectangular grid.

Syntax:

matplotlib.pyplot.pcolormesh(\*args, alpha=None, norm=None, cmap=None, vmin=None, vmax=None, shading='flat', antialiased=False, data=None, \*\*kwargs)

Parameters: This method accept the following parameters that are described below:

• C : This parameter contains the values in 2D array which are to be color-mapped.
• X, Y: These parameter are the coordinates of the quadrilateral corners.
• cmap : This parameter is a colormap instance or registered colormap name.
• norm : This parameter is the Normalize instance scales the data values to the canonical colormap range [0, 1] for mapping to colors
• vmin, vmax : These parameter are optional in nature and they are colorbar range.
• alpha : This parameter is a intensity of the color.
• snap : This parameter is used to snap the mesh to pixel boundaries.
• edgecolors : This parameter is the color of the edges. {‘none’, None, ‘face’, color, color sequence}
• shading : This parameter is the fill style. It can be flat or gouraud.

Returns: This returns the following:

• mesh : This returns the matplotlib.collections.QuadMesh

Below examples illustrate the matplotlib.pyplot.pcolormesh() function in matplotlib.pyplot: Example #1:

Python3

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LogNorm

Z = np.random.rand(25, 25)

plt.pcolormesh(Z)

plt.title('matplotlib.pyplot.pcolormesh() function Example', fontweight ="bold")
plt.show()

Output: Example #2:

Python3

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LogNorm

dx, dy = 0.015, 0.05
y, x = np.mgrid[slice(-4, 4 + dy, dy),
                slice(-4, 4 + dx, dx)]
z = (1 - x / 3. + x ** 6 + y ** 3) * np.exp(-x ** 2 - y ** 2)
z = z[:-1, :-1]
z_min, z_max = -np.abs(z).max(), np.abs(z).max()

c = plt.pcolormesh(x, y, z, cmap ='Greens', vmin = z_min, vmax = z_max)
plt.colorbar(c)

plt.title('matplotlib.pyplot.pcolormesh() function Example', fontweight ="bold")
plt.show()

Output: