Dear list,
this must be an easy one:
I have a data.frame of two columns, "ID" with four different levels (A
to D) and numerical "size", and each of the 4 different IDs is
repeated a
different number of times. I would like to get the mean size for each
ID as another data.frame. I have tried the following:
>ID= as.character(unique(data[,1])) # I use unique() because "data"
will be larger in future
>nIDs = length(ID)
>for(i in 1:nIDs){
+ subdata = subset(data,V1==ID[i])
+ average = as.data.frame(cbind(1:i,ID[i],mean(subdata[,2]))
+ }
Unfortunately, my output only gets the last level of ID four times:
>average
V1 V2 V3
1 1 D 179.777777777778
2 2 D 179.777777777778
3 3 D 179.777777777778
4 4 D 179.777777777778
How can I get what I need? there might be an easier way to do it, but
I guess my skills aren´t that good. Any suggestions are welcome
Regards,
David
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