Nameerror: name plt is not defined

In this article, we will walk you through how to fix the Python nameerror: name ‘plt’ is not defined error.

So, if this error gives you a headache, keep on reading!

This article discusses what this error means, why it occurs, and solutions to fix the nameerror name plt is not defined error message.

What is the “plt” alias in Matplotlib?

The “plt” alias is a commonly used abbreviation for the Matplotlib library, which is used for creating visualizations in Python.

What is “nameerror name plt is not defined”?

The nameerror: name ‘plt’ is not defined error message occurs when you are trying to use the pyplot module from matplotlib library without first importing it.

Why does this error occur?

The error message nameerror: name plt is not defined can occur due to several reasons, it includes the following:

❌ pyplot module is not installed.

❌ Incorrect Spelling “plt.”

❌ If you forget to import the Matplotlib library or import it incorrectly.

❌ When you’re using an older version of Python, you may encounter this error because Matplotlib may not be installed or supported in older versions of Python.

How to fix the “nameerror: name ‘plt’ is not defined

To fix the nameerror name plt is not defined, you have to install matplotlib and import plt before using it. This error is the same as nameerror: name plot is not defined.

Solution 1: Install the matplotlib library

If you are using Python 2:

✅ pip install matplotlib

If you are using Python 3:

✅ pip3 install matplotlib

or

✅ python3 -m pip install matplotlib

If you are using Anaconda:

✅ conda install -c conda-forge matplotlib

if you don’t have pip in your PATH environment variable:

✅ python -m pip install matplotlib

If you get a permissions error:

✅ sudo pip3 install matplotlib

If you are using Ubuntu or Debian:

✅ sudo apt-get install python3-matplotlib

Solution 2: Import the pyplot module from matplotlib using the plt alias

This is the most common solution to fix this error. You can do this by adding the following line at the start of your code:

 ✅ import matplotlib.pyplot as plt

For example:

✅ import matplotlib.pyplot as plt

a = [10, 20, 30, 40, 50]
b = [20, 40, 60, 80, 100]

plt.plot(a, b)
plt.show()

Output:

Solution 3: Use different alias

When you have a conflict with the “plt” alias, you can use different alias for the Matplotlib library.

✅ import matplotlib.pyplot as myplot

a = [10, 20, 30, 40, 50]
b = [20, 40, 60, 80, 100]

myplot.plot(a, b)
myplot.show()

As you can see we use new alias, “myplot“, for the Matplotlib library. Then we plots a simple line graph and displays it using the “show()” function.

When you try to run this code, it should display the line graph without any errors.

Output:

Solution 4: Import specific functions

You can import specific functions or variables from the pyplot module. If you only need specific functions from the Matplotlib library, you can import them directly instead of importing the entire library.

For example:

✅ from matplotlib.pyplot import plot, show

a = [1, 2, 3, 4, 5]
b = [6, 7, 8, 9, 10]

plot(a, b)
show()

Output:

Solution 5: Check Your Installation

If none of the above solutions fix the error, you need to check your Matplotlib installation. Ensure you have installed Matplotlib correctly and that it is up to date.

You can check your installation using the following code:

✅ import matplotlib

print(matplotlib.__version__)

Conclusion

In conclusion, the nameerror: name ‘plt’ is not defined error message occurs when you are trying to use the pyplot module from matplotlib library without first importing it.

To fix the error you have to install the matplotlib and import plt modulebefore using it.

This article already provides solutions for this error to help you fix the Python error message.

You could also check out other “nameerror” articles that may help you in the future if you encounter them.

• Nameerror name np is not defined
• Nameerror name ‘raw_input’ is not defined
• Nameerror name ‘model’ is not defined

Hoping that this article helps you fix the error. Thank you for reading itsourcecoders 😊