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Matplotlib.axes.Axes.pcolorfast() 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.pcolorfast() Function

The Axes.pcolorfast() function in axes module of matplotlib library is also used to create a pseudocolor plot with a non-regular rectangular grid.It has some limitations : supports only flat shading, lack of log scaling and lack of pyplot wrapper.
Syntax: Axes.pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None, vmax=None, data=None, **kwargs) pcolorfast([X, Y, ] C, **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.
Returns: This returns the following:
  • image: This returns the image depend on AxesImage, PcolorImage and QuadMesh .
Below examples illustrate the matplotlib.axes.Axes.pcolorfast() function in matplotlib.axes: Example-1:
# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LogNorm
   
Z = np.random.rand(30, 30)
   
fig, ax0 = plt.subplots()
   
ax0.pcolorfast(Z)
   
ax0.set_title('matplotlib.axes.Axes.pcolorfast() Examples')
plt.show()

                    
Output: Example-2:
# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LogNorm
   
  
dx, dy = 0.15, 0.05
y, x = np.mgrid[slice(-3, 3 + dy, dy), slice(-3, 3 + dx, dx)]
z = (1 - x / 2. + x ** 5 + 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.pcolorfast(x, y, z, cmap ='Greens', vmin = z_min, vmax = z_max)
fig.colorbar(c, ax = ax)
  
ax.set_title('matplotlib.axes.Axes.pcolorfast() Examples')
plt.show()

                    
Output:

Last Updated : 13 Apr, 2020
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