Apply functions on every node in a dendrogram

dend_node_apply(dend, fun)

Arguments

dend: A dendrogram.
fun: A self-defined function.

Details

The function returns a vector or a list as the same length as the number of nodes in the dendrogram.

The self-defined function can have one single argument which is the sub-dendrogram at a certain node. E.g. to get the number of members at every node:


    dend_node_apply(dend, function(d) attr(d, "members"))

The self-defined function can have a second argument, which is the index of current sub-dendrogram in the complete dendrogram. E.g. dend[[1]] is the first child node of the complete dendrogram and dend[[c(1, 2)]] is the second child node of dend[[1]], et al. This makes that at a certain node, it is possible to get information of its child nodes and parent nodes.


    dend_node_apply(dend, function(d, index) {
        dend[[c(index, 1)]] # is the first child node of d, or simply d[[1]]
        dend[[index[-length(index)]]] # is the parent node of d
        ...
    })

Note for the top node, the value of index is NULL.

Value

A vector or a list, depends on whether fun returns a scalar or more complex values.

Examples

mat = matrix(rnorm(100), 10)
dend = as.dendrogram(hclust(dist(mat)))
# number of members on every node
dend_node_apply(dend, function(d) attr(d, "members"))
#>  [1] 10  6  4  1  3  1  2  1  1  2  1  1  4  1  3  1  2  1  1
# the depth on every node
dend_node_apply(dend, function(d, index) length(index))
#>  [1] 0 1 2 3 3 4 4 5 5 2 3 3 1 2 2 3 3 4 4