Subset dataframe using a loop

Question

I have a data frame that looks like this:

index   ID   date              Amount
2       1001 2010-06-08         0
21      1001 2010-10-08        10
6       10         


        

Answer 1

may be like this

    IDs<-unique(df$ID)
    for (i in 1:length(IDs)){ 
    temp <- df[df$ID==IDs[i],]
    #more things to do with temp
    }