I want to join this two dataframes:
id mean
2_1 40
2_3 50
2_4 60
id a
2_1 testa
2_2 testb
2_3 testc
2_4 testd
But because of the missing id in dataframe one, I get this incorrect output with lines slipped:
id mean a
2_1 40 testa
2_3 50 testb
2_4 60 testc
How to merge correctly?
