I have 2 huge Pandas dataframes and have to break them into chunks to compare the data between the dataframes chunk by chunk based on the custom index (Primary Key) and get data mismatch for each column.

I have an issue of performing .diff() and .pct_change() calls on rows. The original table has 51 countries so I will use an example of three countries here as follows:

I have the below columns in my dataframe ABC.