Matplotlib Line Plot with Data Points

Introduction

In this lab, we will learn how to create a line plot with data points using Matplotlib in Python. We will use the EventCollection class in Matplotlib to mark the locations of the x and y data points on the respective axes for each curve.

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Import necessary libraries

First, we need to import the required libraries. We will use numpy to create random data, matplotlib.pyplot to create the plot, and EventCollection from matplotlib.collections to mark the locations of data points.

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.collections import EventCollection

Create random data

We will create random data for two curves using numpy.random.random() function. We will generate two sets of 10 random numbers between 0 and 1 and store them in an array.

## create random data
xdata = np.random.random([2, 10])

Sort the data

To make clean curves, we will sort the data using the sort() method.

## split the data into two parts
xdata1 = xdata[0, :]
xdata2 = xdata[1, :]
## sort the data so it makes clean curves
xdata1.sort()
xdata2.sort()

Create y data points

We will create some y data points for each curve by performing some mathematical operations on the sorted x data points.

## create some y data points
ydata1 = xdata1 ** 2
ydata2 = 1 - xdata2 ** 3

Create the plot

We will create the plot using matplotlib.pyplot.plot() function.

## plot the data
fig = plt.figure()
ax = fig.add_subplot(1, 1, 1)
ax.plot(xdata1, ydata1, color='tab:blue')
ax.plot(xdata2, ydata2, color='tab:orange')

Create the events

We will create the events marking the x and y data points using EventCollection() function.

## create the events marking the x data points
xevents1 = EventCollection(xdata1, color='tab:blue', linelength=0.05)
xevents2 = EventCollection(xdata2, color='tab:orange', linelength=0.05)

## create the events marking the y data points
yevents1 = EventCollection(ydata1, color='tab:blue', linelength=0.05,
                           orientation='vertical')
yevents2 = EventCollection(ydata2, color='tab:orange', linelength=0.05,
                           orientation='vertical')

Add the events to the plot

We will add the events to the plot using matplotlib.pyplot.add_collection() function.

## add the events to the axis
ax.add_collection(xevents1)
ax.add_collection(xevents2)
ax.add_collection(yevents1)
ax.add_collection(yevents2)

Set the limits and add title

We will set the limits of the x and y axes and add a title to the plot using matplotlib.pyplot.xlim(), matplotlib.pyplot.ylim(), and matplotlib.pyplot.title() functions.

## set the limits
ax.set_xlim([0, 1])
ax.set_ylim([0, 1])
ax.set_title('line plot with data points')

Display the plot

Finally, we will display the plot using matplotlib.pyplot.show() function.

## display the plot
plt.show()

Summary

In this lab, we learned how to create a line plot with data points using Matplotlib in Python. We used the EventCollection class in Matplotlib to mark the locations of the x and y data points on the respective axes for each curve.