i have a 'fct' column and 'true' column, how to create a new column with mse for each row in a pandas dataframe in python

If df is the pandas DataFrame containing the columns fct and true, the new column MSE can be created as follows:

main.py
import numpy as np
import pandas as pd

df['MSE'] = np.square(df['fct'] - df['true'])
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This computes the square of the difference between the fct and true columns for each row, and stores the result in the new MSE column.