Answers for "how to append a dataframe to another dataframe in pandas"

pd merge on multiple columns

new_df = pd.merge(A_df, B_df,  how='left', left_on=['A_c1','c2'], right_on = ['B_c1','c2'])

merge two columns name in one header pandas

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

appending dataframes pandas

>>> df = pd.DataFrame([[1, 2], [3, 4]], columns=list('AB'))
>>> df
   A  B
0  1  2
1  3  4
>>> df2 = pd.DataFrame([[5, 6], [7, 8]], columns=list('AB'))
>>> df.append(df2)
   A  B
0  1  2
1  3  4
0  5  6
1  7  8

how to append a dataframe to another dataframe in pandas

# all_res is list of DataFrames : [ dataframe, dataframe, ... ]
df_res = pd.concat(all_res)