# rename Pandas columns to lower case
df.columns= df.columns.str.lower()
df.columns
Index(['column1', 'column2', 'column3'], dtype='object')
# Creating 'columnB' that has Uppercase versions of all of columnA's values
df['columnB'] = df['columnA'].str.upper()
df = df.applymap(lambda s:s.lower() if type(s) == str else s)
df['col_name'].str.lower()