**PyLab** is a drawing library interface for **Matplotlib**, and its syntax is very similar to that of **MATLAB**. It can be used together with the **PyPlot** module to implement the drawing function of **Matplotlib**. **PyLab** is a separate module that is installed with the **Matplotlib** package.

### 1. How To Import PyLab & PyPlot.

- First, make sure you have installed the python Matplotlib library, please read the article How To Install Python Package Numpy, Pandas, Scipy, Matplotlib On Windows, Mac, And Linux.
- Then you can use the below python source code to import the
**PyLab**&**PyPlot**modules.# below code can import the Pyplot library. from matplotlib import pytplot as plt # you can use the below 2 way to import the PyLab library. import pylab # import all the sub classes in the pylab module. from pylab import *

### 2. Draw Curve Examples With PyLab Plot Function.

#### 2.1 Draw Quadratic Curve.

- Below is the python source code.
>>> from pylab import * # import all the methods from the pylab library. >>> >>> x = linspace(-3, 3, 30) # calculate the x axis values. >>> >>> y = x**2 # the y axis value is x**2 >>> >>> plot(x, y) # draw the quadratic curve. [<matplotlib.lines.Line2D object at 0x000001E1C4A26A60>] >>> show() # show the curve picture.

- Below is the quadratic curve graph.

#### 2.2 Draw Red Dot Quadratic Curve.

- Below is the python source code.
>>> from pylab import * # import the pylab library. >>> >>> x = linspace(-3, 3, 30) # calculate the x axis values >>> >>> y = x**2 # the y axis value is x**2 >>> >>> plot(x, y, 'r.') # r means red and . means dot line. [<matplotlib.lines.Line2D object at 0x000001E1C9AFC220>] >>> show()

- Below is the example graph.

#### 2.3 Draw Multiple Curves.

- Below is the example source code.
>>> from pylab import * # import the pylab module. >>> >>> plot(x, cos(x), 'b.') # plot a blue cos curve use the dot line. [<matplotlib.lines.Line2D object at 0x000001E1CE4392B0>] >>> >>> plot(x, -sin(x), 'r--') # plot a red -sin curve use two short line. [<matplotlib.lines.Line2D object at 0x000001E1CE439730>] >>> >>> plot(x, sin(x), 'g-') # plot a green sin curve use single short line. [<matplotlib.lines.Line2D object at 0x000001E1CE439AF0>] >>> >>> show() # show the multiple curve graph.

- Below is the above example generated graph.