Problem

Write a function that takes in a dataframe and a list of column names and returns a new dataframe with only the columns in the list.
Example input:
df = pd.DataFrame({'col1': [1, 2, 3], 'col2': [4, 5, 6], 'col3': [7, 8, 9]})
columns_to_keep = ['col1', 'col3']
Example output:
df = pd.DataFrame({'col1': [1, 3], 'col3': [7, 9]})

Solution

import pandas as pd

def keep_columns(df, columns_to_keep):
    return df[columns_to_keep]

df = pd.DataFrame({'col1': [1, 2, 3], 'col2': [4, 5, 6], 'col3': [7, 8, 9]})
columns_to_keep = ['col1', 'col3']

print(keep_columns(df, columns_to_keep))