how to merge columns in pandas code example

Example 1: pandas left join

df.merge(df2, left_on = "doc_id", right_on = "doc_num", how = "left")

Example 2: reorder columns pandas

cols = df.columns.tolist()
# Rearrange the list any way you want
cols = cols[-1:] + cols[:-1]
df = df[cols]

Example 3: pandas merge two columns from different dataframes

#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')

Example 4: python pandas apply to one column

df['a'] = df['a'].apply(lambda x: x + 1)

Example 5: merge two columns pandas

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

Example 6: how to merge two column pandas

DataFrame["new_column"] = DataFrame["column1"] + DataFrame["column2"]