How to calculate percentage change between values using pandas

Calculating percentage difference between values in pandas is a very common task, in this article i will show you some examples one how you can perform such tasks in an easy and efficient manner, lets start!

Calculate the percentage difference between values of a column

Assume that we have a dataframe with one column of 10 integer values ranging from 1 to 100, and we want to add another column to the dataframe that will indicate the percentage change of the values, to create a dataframe with one column with 10 integer values is very easy

import pandas as pd 
import random 
 
# Generate 10 random integer values from 1 to 100 
random_data = [random.randint(1, 100) for _ in range(10)] 
df = pd.DataFrame(random_data, columns=['Values'])

Now we have the dataframe the next step is to calculate a column with the percentage change of each value from the previous value, to do this we will use the .pct_change() function to the Values column and multiply the result with 100.

# Calculate the percentage change and add it as a new column 
df['PctChange'] = df['Values'].pct_change() * 100

Now lets make things a bit more complicate, what if we wanted to calculate the percentage difference not by every row but every second row, to do this we can use the periods option!

df['PctChange'] = df['Values'].pct_change(periods=2) * 100

This will calculate the percentage difference of row versus every second row

Calculate the percentage difference between two columns of the same dataframe

Now assume that we have two columns and we need to calculate the percentage difference between the correspoding values of the columns, lets create first our dataframe

import pandas as pd 
import random 
 
# Generate 10 random integer values from 1 to 100 
random_data_1 = [random.randint(1, 100) for _ in range(10)] 
random_data_2 = [random.randint(1, 100) for _ in range(10)] 
df = pd.DataFrame(random_data, columns=['Values1']) 
df['Values2'] = random_data_2

Now lets calculate the percentage difference which is a very straight forward math operation!

df['Percentage_Diff'] = ((df['Values2'] - df['Values1']) / df['Values1']) * 100

Conclusion

Calculating percentage change of rows is a very essential but easy task! i hope this article made it clear for you on how to achieve this!