How To Check If A String Is Nan In Python

In Python, you’ll often encounter situations where you need to check if a given string is a representation of Not a Number (NaN). This tutorial will guide you through a simple method to check if a string is NaN in Python, using a function provided by the Pandas library.

Step 1: Install the Pandas Library

Before you start, you need to install the Pandas library, which can be done using pip, a package installer for Python. Open your terminal/command prompt and type the following command:

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pip install pandas

Once the installation is complete, you can proceed to use Pandas in your Python code.

Step 2: Import Pandas Library

In your Python script, you need to import the Pandas library. Add the following line at the beginning of your script:

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import pandas as pd

Step 3: Create the is_nan Function

Now, create a function called is_nan that will accept a string as input and return True if the string is NaN and False otherwise. The function will use the pd.isna() function from Pandas library:

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def is_nan(string):
    return pd.isna(string)

Step 4: Test the is_nan Function

You can now test the is_nan function by providing a few test cases:

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print(is_nan("NaN"))  # Output: True
print(is_nan("123"))  # Output: False
print(is_nan("NaN1"))  # Output: False
print(is_nan(""))  # Output: False

Full Code

Here is the complete Python script described in this tutorial:

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import pandas as pd
 
def is_nan(string):
    return pd.isna(string)
 
print(is_nan("NaN"))
print(is_nan("123"))
print(is_nan("NaN1"))
print(is_nan(""))

Output

True
False
False
False

Conclusion

In this tutorial, you learned how to check if a string is NaN in Python by using the Pandas library and the pd.isna() function. This simple approach ensures that your Python code can efficiently and accurately determine if a given string represents a NaN value.