Matplotlib.artist.Artist.set_transform() in Python

Last Updated : 15 May, 2020

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. The Artist class contains Abstract base class for objects that render into a FigureCanvas. All visible elements in a figure are subclasses of Artist.

Matplotlib.artist.Artist.set_transform() Method

The set_transform() method in artist module of matplotlib library is used to set the artist transform.

Syntax: Artist.set_transform(self, t)

Parameters: This method accepts only one parameters.

t : This parameter is the Transform.

Returns: This method does not return any value.

Below examples illustrate the matplotlib.artist.Artist.set_transform() function in matplotlib:

Example 1:

python3

# Implementation of matplotlib function
from matplotlib.artist import Artist 
import numpy as np 
import matplotlib.pyplot as plt 
import matplotlib.transforms as mtransforms 

  
delta = 0.25

x = y = np.arange(-3.0, 3.0, delta) 
X, Y = np.meshgrid(x, y) 

Z1 = np.exp(-X**2 - Y**2) 
Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2) 
Z = (Z1 - Z2) 
  
transform = mtransforms.Affine2D().rotate_deg(30) 
fig, ax = plt.subplots() 
      
im = ax.imshow(Z, interpolation ='none', 
               origin ='lower', 
               extent =[-2, 4, -3, 2],  
               clip_on = True) 
  
trans_data = transform + ax.transData 
Artist.set_transform(im, trans_data) 
  
x1, x2, y1, y2 = im.get_extent() 
ax.plot([x1, x2, x2, x1, x1],  
        [y1, y1, y2, y2, y1], 
        "ro-", 
        transform = trans_data) 
  
ax.set_xlim(-5, 5) 
ax.set_ylim(-4, 4) 

plt.title("""matplotlib.artist.Artist.set_transform()
function Example""", fontweight="bold")

plt.show()

Output:

Example 2:

python3

# Implementation of matplotlib function
from matplotlib.artist import Artist 
import matplotlib.pyplot as plt 
from matplotlib import collections, colors, transforms 
import numpy as np 

   
nverts = 50
npts = 100
   
r = np.arange(nverts) 
theta = np.linspace(0, 2 * np.pi, nverts) 

xx = r * np.sin(theta) 
yy = r * np.cos(theta) 

spiral = np.column_stack([xx, yy]) 
   
rs = np.random.RandomState(19680801) 
   
xyo = rs.randn(npts, 2) 
   
colors = [colors.to_rgba(c) 
          for c in plt.rcParams['axes.prop_cycle'].by_key()['color']] 
   
fig, ax1 = plt.subplots() 
   
col = collections.RegularPolyCollection( 
    7, sizes = np.abs(xx) * 10.0,  
    offsets = xyo,  
    transOffset = ax1.transData) 
  
trans = transforms.Affine2D().scale(fig.dpi / 72.0) 
Artist.set_transform(col, trans)  
  
ax1.add_collection(col, autolim = True) 
col.set_color(colors)

plt.title("""matplotlib.artist.Artist.set_transform()
function Example""", fontweight="bold")

plt.show()