How to Replace Infinite Values in Python

Working with various kinds of data in Python often means encountering infinite values. When analyzing large datasets, you may come across these values which can interfere with the reliability of your results. In this tutorial, we will cover several methods to detect and replace these infinite values in your Python project.

Recognizing infinite values

Python recognizes infinite values as a special kind of float. They are defined using the term float('inf') for positive infinity and float('-inf') for negative infinity. These infinite values can participate in operations just like normal float numbers.

Identifying infinite values in a list

To identify infinite values in an array or list, you can use the “math” module’s math.isinf() function. Here’s how to do it:

1
2
3
4
import math
 
numbers = [1, 2, float('inf'), -3, float('-inf')]
infinity_list = [num for num in numbers if math.isinf(num)]

In the snippet above, the list comprehension loops through the numbers and selects only the elements that are infinite.

Sealing with infinite values in pandas DataFrame

If you are dealing with pandas DataFrame, you can identify infinite values using the np.isinf() function from Numpy. Below is an example of how you can use this function:

1
2
3
4
5
6
import pandas as pd
import numpy as np
 
data = {'A': [1, 2, np.inf, 4], 'B': [-4, np.inf, -np.inf, 6]}
df = pd.DataFrame(data)
infinite_df = df[df.apply(lambda series: np.isinf(series)).any(axis=1)]

Replacing infinite values

To replace infinite values in Python, you can use the replace() function, which allows you to replace certain values in your data.

1
df.replace([np.inf, -np.inf], np.nan)

In this code segment, all infinite values in the DataFrame are replaced with NaN values.

Full Code

1
2
3
4
5
6
7
8
9
10
import math
import pandas as pd
import numpy as np
 
numbers = [1, 2, float('inf'), -3, float('-inf')]
infinity_list = [num for num in numbers if math.isinf(num)]
data = {'A': [1, 2, np.inf, 4], 'B': [-4, np.inf, -np.inf, 6]}
df = pd.DataFrame(data)
infinite_df = df[df.apply(lambda series: np.isinf(series)).any(axis=1)]
df.replace([np.inf, -np.inf], np.nan)

In the above code, we first identify and then deal with infinite values in a list and pandas DataFrame.

Conclusion

Dealing with infinite values is an integral part of Python programming, particularly while working with large datasets.

Recognizing, identifying, and replacing these values can help maintain the reliability of your data analysis results. So, making use of available Python libraries like NumPy for handling them can make your computation tasks more streamlined and efficient.