Matplotlib pylab Module

PyLab is the process interface of Matplotlib's object-oriented plotting library. Matplotlib is the entire package; matplotlib.pyplot is a module in Matplotlib; it and PyLab are modules installed with Matplotlib.

PyLab is a very convenient module that can batch import matplotlib.pyplot (for plotting) and NumPy (for mathematics and using arrays) in a single namespace. Although there are many examples using PyLab, it is no longer recommended to use it.

Basic plotting

Drawing curves is completed using the plot command, which requires a pair of arrays (or sequences) of the same length, as shown in the following example code -

# Filename : example.py
# Copyright :　2020 By w3codebox
# Author by : www.oldtoolbag.com
# Date :　2020-08-08
#!　/usr/bin/env python
　#coding=utf-8
　from numpy import　*
　from pylab import　*
　x = linspace(-3,　3,　30)
　y = x**2
　#plt.title('title')
　plot(x, y)
　show()

Execute the above code line to generate the following result -

If you want to draw symbols instead of lines, please provide other string parameters. The available symbol parameters are as follows:

Symbols: ^ , v , < , > , s , + , x , D , d , 1 , 2 , 3 , 4 , h , H , p , | , _ , - , –, -, , . , , , o , Color: b, g, r, c, m, y, k, w

Next, let's take a look at the following code -

# Filename : example.py
# Copyright :　2020 By w3codebox
# Author by : www.oldtoolbag.com
# Date :　2020-08-08
from pylab import　*
　x = linspace(-3,　3,　30)
　y = x**2
　plot(x, y, 'r|')
　show()

Executing the above example code gives the following result -

You can overlay plots. Just use multiple plotting commands. Use clf() to clear the plot.

# Filename : example.py
# Copyright :　2020 By w3codebox
# Author by : www.oldtoolbag.com
# Date :　2020-08-08
#!　/usr/bin/env python
　#coding=utf-8
　from pylab import　*
　x = linspace(-3,　3,　30)
　y = x**2
　plot(x, sin(x))
　plot(x, cos(x), 'r-')
　plot(x,　-sin(x), 'g--')
　show()

The following code line generates the following output -