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Matplotlib.axes.Axes.pcolormesh() in Python

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Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. The Axes Class contains most of the figure elements: Axis, Tick, Line2D, Text, Polygon, etc., and sets the coordinate system. And the instances of Axes supports callbacks through a callbacks attribute.

matplotlib.axes.Axes.pcolormesh() Function

The Axes.pcolormesh() function in axes module of matplotlib library is also used to create a pseudocolor plot with a non-regular rectangular grid. It is more specialized than pcolor for the given purpose and thus is faster. It supports Gouraud shading

Syntax: Axes.pcolormesh(self, *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.axes.Axes.pcolormesh() function in matplotlib.axes: 

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)
   
fig, ax0 = plt.subplots()
   
ax0.pcolormesh(Z)
   
ax0.set_title('matplotlib.axes.Axes.pcolormesh() Examples')
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()
 
fig, ax = plt.subplots()
   
c = ax.pcolormesh(x, y, z, cmap ='Greens', vmin = z_min,
                  vmax = z_max)
 
fig.colorbar(c, ax = ax)
ax.set_title('matplotlib.axes.Axes.pcolormesh() Examples')
plt.show()

                    

Output:

 



Last Updated : 02 Nov, 2022
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