R- Collapse rows and sum the values in the column
问题 I have the following dataframe (df1): ID someText PSM OtherValues ABC c 2 qwe CCC v 3 wer DDD b 56 ert EEE m 78 yu FFF sw 1 io GGG e 90 gv CCC r 34 scf CCC t 21 fvb KOO y 45 hffd EEE u 2 asd LLL i 4 dlm ZZZ i 8 zzas I would like to collapse the first column and add the corresponding PSM values and I would like to get the following output: ID Sum PSM ABC 2 CCC 58 DDD 56 EEE 80 FFF 1 GGG 90 KOO 45 LLL 4 ZZZ 8 It seems doable with aggregate function but don't know the syntax. Any help is really