How to Draw a Figure

In this lesson, we will learn how to draw a line on a canvas by using the function subplot().

Let’s draw our first figure by following a step-by-step process. This process will teach us how to draw a figure using the formal method. In this figure, we will draw two lines. Each will be generated from a defined number, obtained by using numpy.

Step 1 - Create a dataset

We will start by creating our dataset, which will consist of two lines. In this example, we will use numpy to generate a series of points on the x-axis. Then, we will use sin to generate a corresponding series of points on the y-axis.

import numpy as np

points = np.linspace(-5, 5, 256)
y1 = np.power(points, 3) + 2.0
y2 = np.sin(points) - 1.0

Step 2 - Create a canvas

We will then create a canvas with only one axis. The function subplots() helps us create a figure, or canvas, with a specified layout. If we don’t pass the nrows or ncols parameters, subplots() will create a canvas with only one axes.

import matplotlib.pyplot as plt
fig, axe = plt.subplots()

Step 3 - Add data to the axes

Next, we will add data to the axes by using plot. By default, the first argument is for the x-axis, and the second argument is for the y-axis.

axe.plot(points, y1)
axe.plot(points, y2)

Step 4 - Show the figure

We can show our figure by calling

Notice: The plt here is a reference to matplotlib.pyplot.

NOTICE: The code above is different from the code below. On a PC, we can call to display an image on the screen. However, in the example code below, we need to output the image as a file.

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