Matplotlib Timeseries Line Plot: A Complete Guide

NISHANT TIWARI 10 Feb, 2024 • 6 min read

Introduction

This article delves into the intricate art of data visualization and demystifies the process of creating, customizing, and interpreting timeseries line plots. Whether you’re a seasoned data analyst or a budding enthusiast, join us as we navigate through the essentials and intricacies of Matplotlib, equipping you with the tools to harness the power of timeseries data visualization.

What is Timeseries Line Plot?

A Timeseries Line Plot is a graphical representation of data points plotted against time. It is a powerful tool in data visualization that helps us understand patterns, trends, and relationships in time-dependent data. Plotting data points on a line graph allows us to quickly identify any changes or fluctuations over time.

Importance of Timeseries Line Plots in Visualization

Timeseries Line Plots play a crucial role in data visualization for several reasons. Firstly, they allow us to visualize our data’s temporal patterns and trends, making it easier to identify any seasonality, trends, or anomalies. This is particularly useful in finance, economics, and weather forecasting, where understanding time-dependent patterns is essential.

Secondly, Timeseries Line Plots help us analyze and compare multiple time series datasets. Plotting various lines on the same graph allows us to quickly compare the trends and patterns between different variables or categories.

Lastly, Timeseries Line Plots clearly and concisely represent complex data. Labels, legends, and annotations help us effectively communicate our findings to a broader audience.

Also Read: A Comprehensive Guide to Time Series Analysis and Forecasting

Getting Started with Matplotlib

Installing Matplotlib

To start with Matplotlib, you must first install it on your system. Installing Matplotlib is a straightforward process. You can install it using pip, which is the package installer for Python. Open your command prompt or terminal and type the following command:

Code:

pip install matplotlib

Once the installation is complete, you can verify it by importing the library in your Python script without errors.

Importing the Required Libraries

After installing Matplotlib, import the required libraries in your Python script. Along with Matplotlib, you must also import NumPy and Pandas libraries for data manipulation and analysis. Here is an example of how you can import these libraries:

Code:

import matplotlib.pyplot as plt

import numpy as np

import pandas as pd

By importing these libraries, you will have access to various functions and methods that will help you create and customize your time series line plots.

Creating a Basic Timeseries Line Plot

Here, we will learn how to create a basic timeseries line plot using Matplotlib. We will start by loading and preparing the data, then proceed to plot the timeseries line plot. After that, we will customize the plot by adding labels and titles.

Loading and Preparing the Data

To create a timeseries line plot, we need a dataset containing time-related information. We can use various data sources, such as CSV and Excel files, or even create a short dataframe to plot values.

For example, let’s say we have a dataset that contains a week’s daily temperature readings. We can load this data into a pandas DataFrame and convert the date column to a datetime object.

Code:

import pandas as pd

# Create a DataFrame with date and temperature columns

data = {'date': ['2024-02-01', '2024-02-02', '2024-02-03', '2024-02-04', '2024-02-05', '2024-02-06', '2024-02-07'],

        'temperature': [18, 17, 21, 20, 20, 19, 20]}

df = pd.DataFrame(data)

# Convert the date column to datetime object

df['date'] = pd.to_datetime(df['date'])

df.head()

Output:

Matplotlib Timeseries Line Plot: A Complete Guide

Plotting the Timeseries Line Plot

Once the data is prepared, we can use Matplotlib to create a timeseries line plot. The `plot()` function from Matplotlib creates the line plot.

Code:

import matplotlib.pyplot as plt

# Plot the timeseries line plot

plt.plot(df['date'], df['temperature'])

# Display the plot

plt.show()

Output:

Customizing the Plot

We can customize the timeseries line plot by adding grid lines, axis labels, legends, and xticks using the functions provided by Matplotlib.

Code:

import matplotlib.pyplot as plt

# Plot the timeseries line plot

plt.plot(df['date'], df['temperature'])

# Add grid lines

plt.grid(True)

# Add x-axis and y-axis labels

plt.xlabel('Date')

plt.ylabel('Temperature')

# Add a title

plt.title('Daily Temperature')

# Rotating the xticks

plt.xticks(rotation = 45)

# Display the plot

plt.show()

Output:

Adding Labels and Titles

To make the timeseries line plot more informative, we can add labels to the data points and a title to the plot. We can use the `annotate()` function from Matplotlib to add labels and the `title()` function to add a title.

Code:

import matplotlib.pyplot as plt

# Plot the timeseries line plot

plt.plot(df['date'], df['temperature'])

# Add labels to the data points

for i in range(len(df)):

    plt.annotate(df['temperature'][i], (df['date'][i], df['temperature'][i]))

# Add a title

plt.title('Daily Temperature')

# Display the plot

plt.xticks(rotation = 45)

plt.show()

Output:

Enhancing Timeseries Line Plots with Matplotlib

This section will explore various ways to enhance our timeseries line plots using Matplotlib. We will learn to change line styles and colors, add gridlines and legends, and adjust axis limits and ticks.

Changing Line Styles and Colors

We can customize the line styles and colors to make our time series line plots more visually appealing. Matplotlib provides a wide range of options for this purpose. We can use line styles such as solid, dashed, dotted, or dash-dot. Additionally, we can choose from various colors to make our plots more vibrant and distinguishable.

Here’s an example of how we can change the line style and color in a timeseries line plot:

Code:

import matplotlib.pyplot as plt

# Create a figure and axis

fig, ax = plt.subplots()

# Plot the timeseries data with a dashed red line

ax.plot(df['date'], df['temperature'], linestyle='--', color='red')

# Add labels and title

ax.set_xlabel('Date')

ax.set_ylabel('Temperature')

ax.set_title('Timeseries Line Plot')

# Show the plot

plt.xticks(rotation = 45)

plt.show()

Output:

Adding Gridlines and Legends

Gridlines can be helpful in timeseries line plots to provide a reference for the data points. We can easily add gridlines to our plots using Matplotlib. Additionally, legends can be added to indicate the meaning of different lines in the plot.

Here’s an example of how we can add gridlines and legends to a timeseries line plot:

Code:

import matplotlib.pyplot as plt

# Create a figure and axis

fig, ax = plt.subplots()

# Plot the timeseries data

ax.plot(df['date'], df['temperature'])

# Add gridlines

ax.grid(True)

# Add a legend

ax.legend(['Value'])

# Add labels and title

ax.set_xlabel('Date')

ax.set_ylabel('Temperature')

ax.set_title('Timeseries Line Plot')

# Show the plot

plt.xticks(rotation = 45)

plt.show()

Output:

Adjusting Axis Limits and Ticks

Gridlines can be helpful to in timeseries line plots to reference the data points. We can easily add gridlines to our plots using Matplotlib. Additionally, legends can be added to indicate the meaning of different lines in the plot.

Here’s an example of how we can adjust the axis limits and ticks in a timeseries line plot:

Code:

import pandas as pd

import matplotlib.pyplot as plt

# Create a DataFrame with date and temperature columns

data = {'date': ['2024-02-01', '2024-02-02', '2024-02-03', '2024-02-04', '2024-02-05', '2024-02-06', '2024-02-07'],

        'temperature': [18, 17, 21, 20, 20, 19, 20]}

df = pd.DataFrame(data)

# Convert the date column to datetime object

df['date'] = pd.to_datetime(df['date'])

# Create a figure and axis

fig, ax = plt.subplots()

# Plot the timeseries data

ax.plot(df['date'], df['temperature'])

# Set the x-axis limits

ax.set_xlim([pd.to_datetime('2024-02-01'), pd.to_datetime('2024-02-10')])

# Set the y-axis limits

ax.set_ylim([10, 25])  # Adjusted the y-axis limit for better visualization

# Add labels and title

ax.set_xlabel('Date')

ax.set_ylabel('Temperature')

ax.set_title('Timeseries Line Plot')

# Rotate the x-axis ticks

plt.xticks(rotation=45)

# Show the plot

plt.show()

Output:

Conclusion

In this comprehensive guide, we have learned how to create timeseries line plots using Matplotlib. We explored the process of importing and preprocessing timeseries data and the steps to plot the data using Matplotlib. Additionally, we enhanced our plots by changing line styles and colors, adding gridlines and legends, and adjusting axis limits and ticks. We can create visually appealing and informative timeseries line plots for various applications by following these techniques.