How To Plot Graph In Python Using Text File

Python is one of the most popular programming languages among data scientists, developers, and researchers.

It provides an easy-to-learn syntax, a broad range of libraries to use, and a wide variety of applications. One of its key strengths is its ability to easily generate graphs and visualizations.

However, many users may not know how to plot a graph in Python using a text file. In this tutorial, we will guide you through the process of generating a graph in Python using data from a text file.

Steps:

Step 1: Create a file with data

Create a text file called “data.txt” and fill it with the following data:

0.0 1.0
1.0 2.0
2.0 3.0
3.0 4.0
4.0 5.0
5.0 6.0

Step 2: Import two libraries: NumPy and Matplotlib.

NumPy is a fundamental library for scientific computing, and Matplotlib is a library for creating static, animated, and interactive visualizations in Python. Open a new Python file and type the following code:

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import numpy as np
    import matplotlib.pyplot as plt

Step 3: Load the data from the text file.

Let’s assume that our data is contained in a text file named ‘data.txt’, and it has two columns: x and y. To load the data, we will use the loadtxt() function from NumPy. Type the following code:

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data = np.loadtxt('data.txt')

This will load the data from the ‘data.txt’ file into a NumPy array named ‘data’.

Step 4: Generate the graph using the data in the NumPy array.

To do this, we will use the plot() function from Matplotlib. Type the following code:

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plt.plot(data[:,0], data[:,1])
    plt.show()

This code will create a simple line graph using the x values in the first column and y values in the second column of the ‘data’ array.

Step 5: Add more details to the graph

You can add labels for the x and y axes, a title, or a legend, you can use various functions from Matplotlib. Type the following code:

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plt.plot(data[:,0], data[:,1])
    plt.xlabel('X-axis label')
    plt.ylabel('Y-axis label')
    plt.title('Graph title')
    plt.legend(['Legend label'])
    plt.show()

This code will create a labeled line graph with a title and a legend.

Step 6: Save the graph as a file using the savefig() function from Matplotlib.

Type the following code:

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plt.plot(data[:,0], data[:,1])
    plt.xlabel('X-axis label')
    plt.ylabel('Y-axis label')
    plt.title('Graph title')
    plt.legend(['Legend label'])
    plt.savefig('graph.png')
    plt.show()

This code will save the graph as a PNG file named ‘graph.png’ in the same directory as your Python file.

Full code:

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import numpy as np
import matplotlib.pyplot as plt
 
data = np.loadtxt('data.txt')
plt.plot(data[:,0], data[:,1])
plt.xlabel('X-axis label')
plt.ylabel('Y-axis label')
plt.title('Graph title')
plt.legend(['Legend label'])
plt.savefig('graph.png')
plt.show()

Conclusion:

Generating a graph in Python using a text file is a simple process that involves loading the data, plotting the graph using Matplotlib, and adding details such as labels and a legend.

With this tutorial, you should be able to create basic graphs and customize them according to your needs.

Output: