Dear all,

I want to calculate mean values for multiple rows:

structure(list(Name = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L,
2L, 2L), .Label = c("AKT", "CKT"), class = "factor"), val1 = c(2,
3, 2, 2, 2, 5, 3, 8, 2), val2. = c(4, 5, 4, 8, 4, 8, 4, 7, 4),
    val3 = c(5, 6, 5, 9, 5, 9, 5, 9, 5)), .Names = c("Name",
"val1", "val2.", "val3"), class = "data.frame", row.names = c(NA,
9L))

For example: as an output I must get

 Name val1 val2  val3  AKT   CKT

I wrote this :


#as.matrix(tapply(dat[,2:4], dat[,1], FUN = mean))

Error in as.matrix(tapply(met[, 2:4], met[, 1], FUN = mean)) :
  error in evaluating the argument 'x' in selecting a method for function
'as.matrix': Error in tapply(met[, 2:4], met[, 1], FUN = mean) :
  arguments must have same length

Thanks for you kind advise


Nico

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