changing values in dataframe in Python

# Changing values in a column
titanic.loc[1:3, "age"] = 42
titanic.loc[1:4, 3] = [43, 44, 45]
titanic.loc[titanic.age < 1, "age"] = 1

# Changing values in a row
titanic.loc[0, "survived" : "sex"] = [1, 1, "female"]

######################################
titanic.replace(0, "Zero")