Merge two pandas DataFrames

merge_dfs.py

def merge_dfs(df1, df2):
    """Merge two DataFrames. Common columns among the dfs are reduced to one."""
    res = pd.merge(df1, df2, how='outer', left_index=True, right_index=True)
    cols = sorted(res.columns)
    pairs = []
    for col1, col2 in zip(cols[:-1], cols[1:]):
        if col1.endswith('_x') and col2.endswith('_y'):
            pairs.append((col1, col2))
    for col1, col2 in pairs:
        res[col1[:-2]] = res[col1].combine_first(res[col2])
        res = res.drop([col1, col2], axis=1)
    return res