Plotting with Matplotlib

Data visualisation means showing data in a graphical or pictorial form, so that we can see variation and relationships at a glance, which is hard to do from a table of numbers.

Python's Matplotlib library draws charts. Install it with pip install matplotlib, and import its plotting module with import matplotlib.pyplot as plt (plt is just a short alias; any name would work).

The basic steps:

• plt.plot(x, y) draws a line chart by default, with x values on the horizontal axis and y values on the vertical axis;
• plt.show() displays the figure;
• plt.savefig('chart.png') saves the figure as an image file.

Pyplot has functions for other kinds of chart too: bar() (bar chart), boxplot(), hist() (histogram), pie() and scatter(). plot, then show.