On 2012-07-08 06:57, fabiano wrote:
Thanks Peter.

We had a look at both Hab and habitat. These are integers representing
habitat types.

habitat <- read.csv("Ungulate_vegetation.csv")
habitat <- habitat[,3]
habitat
[1] 3 3 4 3 3 3 4 4 3 3 3 3 3 4 2 3 2 3 2 3

Hab <- cbind(seq(1,20),habitat)
Hab
          habitat
  [1,]  1       3
  [2,]  2       3
  [3,]  3       4
  [4,]  4       3
  [5,]  5       3
  [6,]  6       3
  [7,]  7       4
  [8,]  8       4
  [9,]  9       3
[10,] 10       3
[11,] 11       3
[12,] 12       3
[13,] 13       3
[14,] 14       4
[15,] 15       2
[16,] 16       3
[17,] 17       2
[18,] 18       3
[19,] 19       2
[20,] 20       3

hab
      [,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,]   NA   NA   NA   NA   NA   NA   NA
[2,]   NA   NA   NA   NA   NA   NA   NA

for(i in 1:2){ hab[i, ] <- Hab[habitat==i,1] }

The idea is to assign habitat types to hab.

I don't understand how this relates to a 2-by-7 matrix,
but it's easy to see where your problem with the loop is.
Try this and see if it sheds light:

  hab[1,] <- Hab[habitat==1,1]
  #Error in hab[1, ] <- Hab[habitat == 1, 1] : replacement has length zero

  hab[2,] <- Hab[habitat==2,1]
  #Error in hab[2, ] <- Hab[habitat == 2, 1] :
  number of items to replace is not a multiple of replacement length

Now do:
  Hab[habitat==1,1]    ## how many 1s are in habitat?
  Hab[habitat==2,1]    ## how many 2s are in habitat?

I think that you may have to rethink your approach.

Peter Ehlers


Thanks

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