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Making charts with python matplotlib

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About matplotlib

Matplotlib is a python plotting library which can help generate plots, and charts.

Installation

Install python3 matplotlib on my Ubuntu 16.04 box

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$ sudo apt install python3-matplotlib

Creating a simple chart in python shell

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$ python3
Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import matplotlib.pyplot as plt
>>> plt
<module 'matplotlib.pyplot' from '/usr/lib/python3/dist-packages/matplotlib/pyplot.py'>
>>> x = range(10) # create X coordinate data
>>> y = [ i*i for i in x ] # create Y coordinate data with square of data on X.
>>> plt.plot(x, y)
[<matplotlib.lines.Line2D object at 0x7f4f7d4433c8>]
>>> plt.show()

Then I got the chart

Creating a bar chart

Next I wrote a script to generate a bar chart of the average monthly high temperature of San Francisco.

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import matplotlib.pyplot as plt
def main():
    print('This program will generate a bar chart of the monthly average high temperature of San Francisco')
    # Create the list of X and Y cordinate data
    left_edges = [ i for i in range(12)]
    temperature = [57, 60, 62, 63, 64, 66, 67, 68, 70, 69, 63, 57]
    bar_width = 0.3
    plt.bar(left_edges, temperature, bar_width, color=('r','g','b','r','k','r','g','b','r','k','r','g'))
    # Add a title
    plt.title('San Francisco Climate Graph-Chart')
    # Add the label to the axes
    plt.xlabel('Month')
    plt.ylabel('Average High Temperature')
    # Customize the tick marks
    months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    plt.xticks(left_edges, months)
    plt.yticks([50, 55, 60, 65, 70, 75], ['50F', '55F', '60F', '65F', '70F', '75F'])
    # Add a grid
    plt.grid(True)
    # Display the bar chart graph
    plt.show()

main()

Then I got the bar chart

Creating a pie chart

This script I wrote generates a pie chart of the Population for California by race in 2017 and 2016

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import matplotlib.pyplot as plt
def main():
    print('This program will generate a pie chart of Population for California by race in 2017 and 2016')
    values = [21454, 14014, 2299, 4861, 363, 8600]
    plt.pie(values)
    slice_label = ['White', 'Hispanic', 'Black', 'Asian', 'American Indian', 'Others']
    # Add a title
    plt.title('Population for California by race in 2017 and 2016')
    # Add the label to the axes
    plt.pie(values, labels=slice_label)
    # save the chart image
    plt.savefig('pie_chart.png')
    # Display the pie chart graph
    plt.show()
main()

The pie chart I got

Save the chart to a image file

Just use the savefig() method.

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plt.savefig('bar_chart.png')