[matplotlib]How to Specify a Color[figure, marker, legend]

This article shows how to specify a color in matplotlib.

A list of color names available in matplotlib is explained in the following article.

List of Color Names

How to specify a color

In the beginning, I show how to specify a color.

You can specify a color using the following four ways.

• Specify a color by name
• Specify a color by RGB tuple
• Specify a color by color code
• Specify a color by grayscale
• Specify transparency

Specify a color by name

I show how to specify a color by name.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['b', 'g', 'r', 'tab:cyan', 'teal']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")
plt.show()

The above code generates the following graph.

> colorlist = ['b', 'g', 'r', 'tab:cyan', 'teal']

Describe the color names.

> plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")

Assign colors to bar graphs.

The list of color names is passed to the argument "color=".

Specify a color by RGB tuple

I show how to specify a color by RGB tuple.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = [(0,0,1), (0,1,0), (1,0,0), (0,0,0), (1,1,0)]
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

plt.bar(x, y, color=colorlist, align="center")
plt.show()

The above code generates the following graph.

> colorlist = [(0,0,1), (0,1,0), (1,0,0), (0,0,0), (1,1,0)]

Colors are described by RGB tuple.

> plt.bar(x, y, color=colorlist, align="center")

Assign colors to bar graphs.

The list of colors is passed to the argument "color=".

Specify a color by color code

I show how to specify a color by color code.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['#00008B', '#228B22', '#B22222', '#FFA500', '#8A2BE2']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")
plt.show()

The above code generates the following graph.

> colorlist = ['#00008B', '#228B22', '#B22222', '#FFA500', '#8A2BE2']

Colors are described by color code.

> plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")

The list of colors is passed to the argument "color=".

Specify a color by grayscale

I show how to specify a color by grayscale.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['0', '0.2', '0.4', '0.6', '0.8', '1.0']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")
plt.show()

The above code generates the following graph.

> colorlist = ['0', '0.2', '0.4', '0.6', '0.8', '1.0']

Colors are described by grayscale.

Note that it is written as a string

> plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center")

The list of colors is passed to the argument "color=".

Specify transparency

I show how to specify color transparency.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['b', 'g', 'r', 'tab:cyan', 'teal']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center", alpha=0.5)
plt.show()

The above code generates the following graph.

> plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center", alpha=0.5)

The color transparency can be changed by specifying the argument "alpha=".

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How to change figure background color

I show how to change figure background color.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['b', 'g', 'r', 'yellow', '#8A2BE2']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

fig = plt.figure(figsize = (6,4), facecolor='lightblue')

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center", alpha=0.8)
plt.show()

The above code generates the following graph.

fig = plt.figure(figsize = (6,4), facecolor='lightblue')

A figure object is generated.

The background color can be changed by specifying the argument "facecolor=".

How to change edge color of graph

I show how to change edge color of graph.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['b', 'g', 'r', 'yellow', '#8A2BE2']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=5)

plt.bar(x, y, color=colorlist, tick_label=colorlist, align="center", alpha=0.8)
plt.show()

The above code generates the following graph.

> fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=5)

A figure object is generated.

The line width can be changed by specifying the argument "linewidth=".

The edge color can be changed by specifying the argument "edgecolor=".

How to change figure facecolor

I show how to change figure facecolor.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
colorlist = ['b', 'g', 'r', 'yellow', '#8A2BE2']
x = np.arange(0, len(colorlist))
y = np.repeat(1, len(colorlist))

fig = plt.figure(figsize = (6,4), facecolor='lightblue')
plt.rcParams['axes.facecolor'] = 'lightgray'

plt.bar(x, y, color=colorlist, tick_label=colorlist, align='center', alpha=0.8)

plt.show()

The above code generates the following graph.

> plt.rcParams['axes.facecolor'] = 'lightgray'

The rcParams can be used to make detailed setting.

To change the facecolor, specify the argument 'axes.facecolor'.

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How to change line color

I show how to change line color.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
x = np.linspace(0, 10, 100)
y = np.sin(x)

fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=3)
plt.rcParams['axes.facecolor'] = 'lightgray'

plt.xlabel('X')
plt.ylabel('Y')

plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue')

plt.legend()

plt.show()

The above code generates the following graph.

> plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue')

The line color can be changed by specifying the argument "color=".

How to change marker color

I show how to change marker color.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
x = np.linspace(0, 10, 100)
y = np.sin(x)

fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=3)
plt.rcParams['axes.facecolor'] = 'lightgray'

plt.xlabel('X')
plt.ylabel('Y')

plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue',
        markeredgecolor='k',markerfacecolor='g')

plt.legend()

plt.show()

The above code generates the following graph.

> plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue',
> markeredgecolor='k',markerfacecolor='g')

The marker color can be changed by specifying the argument "markerfacecolor=".

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How to change title color

I show how to change title color.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
x = np.linspace(0, 10, 100)
y = np.sin(x)

fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=3)
fig.suptitle("Title", size=16, color='r')
plt.rcParams['axes.facecolor'] = 'lightgray'

plt.xlabel('X')
plt.ylabel('Y')

plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue',
        markeredgecolor='k',markerfacecolor='g')

plt.legend()

plt.show()

The above code generates the following graph.

> fig.suptitle("Title", size=16, color='r')

The title is added to the figure object.

The title color can be changed by specifying the argument "color=".

How to change legend color

I show how to change legend color.

This is the example code.

import matplotlib.pyplot as plt
import numpy as np
 
x = np.linspace(0, 10, 100)
y = np.sin(x)

fig = plt.figure(figsize = (6,4), facecolor='lightblue', edgecolor='darkblue', linewidth=3)
fig.suptitle("Title", size=16, color='r')
plt.rcParams['axes.facecolor'] = 'lightgray'

plt.xlabel('X')
plt.ylabel('Y')

plt.plot(x, y, linestyle='solid', marker='o', label='sin', color='darkblue',
        markeredgecolor='k',markerfacecolor='g')

plt.legend(facecolor='w', edgecolor='k', labelcolor='r')

plt.show()

The above code generates the following graph.

> plt.legend(facecolor='w', edgecolor='k', labelcolor='r')

You can specify facecolor, edgecolor, and labelcolor.

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