def xact_type(df):
    """
    Adds transfer, expense, income category column to df
    """
    def categorise(row):
        if row['Master Category'] == "Transfer":
            return 'Transfer'
        if row['Master Category'] == "Income":
            return 'Income'
        return 'Expense'

    df['Type'] = df.apply(lambda row: categorise(row), axis=1)