in df if condtion of column is true replace another column code example

Example 1: set value based on column

df.loc[df['c1'] == 'Value', 'c2'] = 10

Example 2: how to change entry in a row based on another columns entry python

import pandas
df = pandas.read_csv("test.csv")
df.loc[df.ID == 103, 'FirstName'] = "Matt"
df.loc[df.ID == 103, 'LastName'] = "Jones"