Matplotlib Hlines and Vlines

Introduction

In this lab, you will learn how to use hlines and vlines functions in Matplotlib. These functions are used to draw horizontal and vertical lines across a plot.

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Skills Graph

Import Libraries

The first step is to import the libraries we need. In this lab, we will be using Matplotlib and NumPy libraries. Matplotlib is a data visualization library and NumPy is used for scientific computing with Python.

import matplotlib.pyplot as plt
import numpy as np

Define Data

The next step is to define the data that we will be using in our plot. We will use NumPy's arange function to create an array of values from 0 to 5 with a step of 0.1. We will use this array as the x-axis. We will also define the y-axis by using the exponential function and sine function from NumPy.

## Define the data
t = np.arange(0.0, 5.0, 0.1)
s = np.exp(-t) + np.sin(2 * np.pi * t) + 1

Add Noise to Data

In this step, we will add some noise to the data to make it more realistic. We will use NumPy's normal function to generate random numbers with a mean of 0.0 and a standard deviation of 0.3.

## Add noise to the data
nse = np.random.normal(0.0, 0.3, t.shape) * s

Create the Plot

Now, we will create the plot using Matplotlib's subplots function. We will create two subplots, one for vertical lines and one for horizontal lines. We will set the figure size to (12, 6) for better visibility.

## Create the plot
fig, (vax, hax) = plt.subplots(1, 2, figsize=(12, 6))

Add Vertical Lines

In this step, we will add vertical lines to the plot. We will use Matplotlib's vlines function to draw the vertical lines. We will also use the transform parameter to set the y-coordinates to be scaled from 0 to 1. We will draw two vertical lines at x=1 and x=2.

## Add vertical lines
vax.plot(t, s + nse, '^')
vax.vlines(t, [0], s)
vax.vlines([1, 2], 0, 1, transform=vax.get_xaxis_transform(), colors='r')
vax.set_xlabel('time (s)')
vax.set_title('Vertical lines demo')

Add Horizontal Lines

In this step, we will add horizontal lines to the plot. We will use Matplotlib's hlines function to draw the horizontal lines. We will draw horizontal lines at y=0.5, y=2.5, and y=4.5.

## Add horizontal lines
hax.plot(s + nse, t, '^')
hax.hlines(t, [0], s, lw=2)
hax.set_xlabel('time (s)')
hax.set_title('Horizontal lines demo')

Display the Plot

Finally, we will display the plot using Matplotlib's show function.

## Display the plot
plt.show()

Summary

In this lab, you learned how to use Matplotlib's hlines and vlines functions to draw horizontal and vertical lines across a plot. You also learned how to add noise to data and create subplots in a figure.