[R] How to append to a list dynamically?

[Nick Angelou]

Hi,

I have a problem with dynamic appending to a list. Here is the list
variable:


clusters <- vector("list", 0)


I extended in the function below:


cluster <- function (pair, clusters)
{
  found <- FALSE
  for (i in length(clusters))
  {
    if (length(intersect(pair, clusters[i])) > 0)
    {
     clusters[i] <- union(clusters[i], pair)
     found <- TRUE
    }
  }
  if (!found)
  {
   clusters <- list(clusters, as.vector(pair))
  }
}


The function is executed in a loop:


for (i in 1:nrow(adjMatrix))
{
for (j in 1:nrow(adjMatrix))
{
  if ((i != j) && adjMatrix[i,j] >0) # the matrix element has to be non-zero
in order to be clustered
  {
    cat(rownames(adjMatrix)[i], colnames(adjMatrix)[j], "\n")
    cluster(as.vector(c(rownames(adjMatrix)[i], colnames(adjMatrix)[j])),
clusters)
  }  
}
}


But the list variable remains empty (i.e. length(clusters) = 0) even though
it should not. Somehow the dynamic extension of the list does not work in
this case. Any suggestions?

Best regards,

Nick
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