Home/ Questions/The dim(x) must have a positive length error: what should you do?
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Lucas Besnard
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Asked: 2022-05-17T12:45:13+00:00 In:

The dim(x) must have a positive length error: what should you do?

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I am new to r and searching the “dim(x) must have a positive length” to understand it better. It seems it doesn’t work as expected when I used some suggestions before. Here is the command line I use:

best_recom <- function(x,n=1) {
  y <- result2[x,order(-result2[x,])[n]]
  inds = which(result2[x,] == y, arr.ind=TRUE)
  recom <- names(inds[1])
  return(recom)
 }
apply(last_visit[,2], 1, best_recom)
dim(X) must have a positive length
apply(as.matrix(last_visit)[,2],1,recomenda_n_melhor)
X1.0 X1.1 X2.1 X3.1
 X1.0 0.0000000 0.5000000 0.3872983 0.3162278
 X1.1 0.5000000 0.0000000 0.2581989 0.0000000
 X2.1 0.3872983 0.2581989 0.0000000 0.0000000
 X3.1 0.3162278 0.0000000 0.0000000 0.0000000
customer cat
 1 1 X5.1
 2 2 X6.1
 3 3 X1.1
 4 4 X2.1

The error I’m getting is below:

dim(X) must have a positive length

Please give me the solution to this issue.

dim(x)
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1 Answer

  1. Best Answer
    Expert

    The cause: The error appears because R coerces last_visit[,2] to a dimensionless vector, whereas apply needs to have some dimensions of the object.

    Solution: You can stop the compulsion by adding drop=F to the command:

    apply(last_visit[,2,drop=F], 1, best_recom)

    Or on the vector, you use lapply or sapply like this:

    lapply(last_visit[,2], best_recom)
    • 23

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