Concatenate two columns in python code example

Example 1: python merge strings in columns

df["period"] = df["Year"].astype(str) + df["quarter"]

Example 2: merge two columns name in one header pandas

df['A'] = df[a_cols].apply(' '.join, axis=1)

Example 3: add two column values of a datframe into one

df["period"] = df["Year"] + df["quarter"]

Example 4: pandas dataframe add two columns int and string

df = df['Day'].map(str) + '-' + df['Month'].map(str) + '-' + df['Year'].map(str)