[R] error: arguments imply differing number

mydata - read.table(textConnection( Id cat1 location item_values p-values sequence a111 1 3002737 100 0.01 1 a112 1 3017821 102 0.05 2 a113 2 3027730 103 0.02 3 a114 2 3036220 104 0.04 4 a115 1 3053984

Re: [R] error: arguments imply differing number

Hi, Thanks for including code and data so that we could reproduce what you're doing. Your problem is that you tell ddply to split the dataset by runNumber and cat1, which results in 4 groups. ddply then applies my.summary() to these four groups. One of these groups (cat1 = 1 and runNumber=1) has

Re: [R] Error: arguments imply differing number of rows

Try str() on both objects and see what you get. It does not look like you have two vectors of length=1762. See this for example = aa - c(A, B, D, D,B, B,D, A, C, C, A,D) bb - rnorm(length(aa)) cc - matrix(rnorm(length(aa)),nrow=2) length(bb)