# Basic syntax:

# If both columns are already string typed:

your_df["combined_col"] = your_df["column_1"] + your_df["column_2"]

# If one (or both) of the columns are not string typed:

your_df["combined_col"] = your_df["column_1"].astype(str) + your_df["column_2"]

df['FullName'] = df[['First_Name', 'Last_Name']].agg('-'.join, axis=1)

#suppose you have two dataframes df1 and df2, and 

#you need to merge them along the column id

df_merge_col = pd.merge(df1, df2, on='id')

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

cols = ['foo', 'bar', 'new']

df['combined'] = df[cols].apply(lambda row: '_'.join(row.values.astype(str)), axis=1)

df["station"] = df["End station"].combine_first(df["Start station"])

df.drop(["End station", "Start station"], 1, inplace=True)