Using `dplyr` you could do `mydata %>% group_by(Date) %>% summarise(across(-1, sum))`. If this doesn't work for you, please edit your question to make your example reproducible.
– Allan CameronNov 14 '20 at 19:31
3
Welcome to [so]! Please read [ask] and give a [mre] in your question! `help(by)`
– jogoNov 14 '20 at 20:51