Matplotlib.colors.to_hex() in Python

Last Updated : 21 Apr, 2020

Matplotlib is an amazing visualization library in Python for 2D plots of arrays. Matplotlib is a multi-platform data visualization library built on NumPy arrays and designed to work with the broader SciPy stack.

matplotlib.colors.to_hex()

The matplotlib.colors.to_hex() function is used to convert numbers between 0 to 1 into hex color code. It uses the #rrggbb format if keep_alpha is set to False(its also the default) else it uses #rrggbbaa.

Syntax: matplotlib.colors.to_hex(c, keep_alpha=False)

Parameters:

c: This represents an array of color sequence between 0 to 1.
keep_alpha: If set True uses #rrggbbaa format else uses #rrggbb format and it only accepts boolean values.

Example 1:

import matplotlib.pyplot as plt 
from matplotlib import colors 
import numpy as np 
  
# dummy data to build the grid 
data = np.random.rand(10, 10) * 20
  
# converting into hex color code 
hex_color=matplotlib.colors.to_hex([ 0.47,  
                                    0.0,  
                                    1.0 ]) 
  
# create discrete colormap 
cmap = colors.ListedColormap([hex_color,  
                              'green']) 
  
bounds = [0,10,20] 
norm = colors.BoundaryNorm(bounds, cmap.N) 
  
fig, ax = plt.subplots() 
ax.imshow(data, cmap=cmap, norm=norm) 
  
# draw gridlines 
ax.grid(which='major', axis='both',  
        linestyle='-', color='k', 
        linewidth=2) 
  
ax.set_xticks(np.arange(-.5, 10, 1)); 
ax.set_yticks(np.arange(-.5, 10, 1)); 
  
plt.show() 

Output:

Example 2:

import matplotlib.pyplot as plt 
from matplotlib import colors 
import numpy as np 
  
# dummy data to build the grid 
data = np.random.rand(10, 10) * 20
  
# converting into hex color 
# code with alpha set to True 
hex_color = matplotlib.colors.to_hex([ 0.47, 
                                      0.0,  
                                      1.0,  
                                      0.5 ], 
                                     keep_alpha = True) 
  
# create discrete colormap 
cmap = colors.ListedColormap([hex_color,  
                              'red']) 
  
bounds = [0, 10, 20] 
norm = colors.BoundaryNorm(bounds, cmap.N) 
  
fig, ax = plt.subplots() 
ax.imshow(data, cmap = cmap, norm = norm) 
  
# draw gridlines 
ax.grid(which ='major', axis ='both',  
        linestyle ='-', color ='k',  
        linewidth = 2) 
  
ax.set_xticks(np.arange(-.5, 10, 1)); 
ax.set_yticks(np.arange(-.5, 10, 1)); 
  
plt.show() 