*59*

Often you may want toÂ **normalizeÂ **the data values of one or more columns in a pandas DataFrame.

This tutorial explains two ways to do so:

**1.Â Min-Max Normalization**

**Objective:**Converts each data value to a value between 0 and 1.**Formula:Â**New value = (value â€“ min) / (max â€“ min)

**2. Mean Normalization**

**Objective:**Scales values such that the mean of all values is 0 and std. dev. is 1.Â**Formula:Â**New value = (value â€“ mean) / (standard deviation)

Letâ€™s check out an example of how to use each method on a pandas DataFrame.

**Example 1: Min-Max Normalization**

Suppose we have the following pandas DataFrame:

import pandas as pd #create DataFrame df = pd.DataFrame({'points': [25, 12, 15, 14, 19], 'assists': [5, 7, 7, 9, 12], 'rebounds': [11, 8, 10, 6, 6]}) #view DataFrame print(df) points assists rebounds 0 25 5 11 1 12 7 8 2 15 7 10 3 14 9 6 4 19 12 6

We can use the following code to apply a min-max normalization to each column in the DataFrame:

(df-df.min())/(df.max()-df.min()) points assists rebounds 0 1.000000 0.000000 1.0 1 0.000000 0.285714 0.4 2 0.230769 0.285714 0.8 3 0.153846 0.571429 0.0 4 0.538462 1.000000 0.0

The max value in each column is now equal toÂ **1Â **and the min value in each column is now equal toÂ **0**, with all other values ranging between 0 and 1.

**Example 2: Mean Normalization**

Once again suppose we have the following pandas DataFrame:

import pandas as pd #create DataFrame df = pd.DataFrame({'points': [25, 12, 15, 14, 19], 'assists': [5, 7, 7, 9, 12], 'rebounds': [11, 8, 10, 6, 6]}) #view DataFrame print(df) points assists rebounds 0 25 5 11 1 12 7 8 2 15 7 10 3 14 9 6 4 19 12 6

We can use the following code to apply a mean normalization to each column in the DataFrame:

(df-df.mean())/df.std() points assists rebounds 0 1.554057 -1.133893 1.227881 1 -0.971286 -0.377964 -0.087706 2 -0.388514 -0.377964 0.789352 3 -0.582772 0.377964 -0.964764 4 0.388514 1.511858 -0.964764

The values in each column are now normalized such that the mean of the values in each column is 0 and the standard deviation of values in each column is 1.

If a particular data point has a normalized value greater than 0, itâ€™s an indication that the data point is greater than the mean of its column. Conversely, a normalized value less than 0 is an indication that the data point is less than the mean of its column.

**Additional Resources**

Pandas: How to Group and Aggregate by Multiple Columns

How to Filter a Pandas DataFrame on Multiple Conditions

How to Count Missing Values in a Pandas DataFrame