gapstat_ord {phyloseq} | R Documentation

## Estimate the gap statistic on an ordination result

### Description

This is a wrapper for the `clusGap` function, expecting an ordination result as the main data argument.

### Usage

    gapstat_ord(ord, axes = c(1:2), type = "sites",
      FUNcluster = function(x, k) {     list(cluster = pam(x, k, cluster.only
      = TRUE)) }, K.max = 8, ...)

### Arguments

`ord` | (Required). An ordination object. The precise class can vary. Any ordination classes supported internally by the phyloseq package should work, ultimately by passing to the `scores` function or its internal extensions in phyloseq.
`axes` | (Optional). The ordination axes that you want to include.
`type` | (Optional). One of `"sites"` (the vegan package label for samples) or `"species"` (the vegan package label for OTUs/taxa). Default is `"sites"`.
`FUNcluster` | (Optional). This is passed to `clusGap`. The documentation is copied here for convenience: a function which accepts as first argument a (data) matrix like `x`, second argument, say (the number of desired clusters) `k`, where `k >= 2`, and returns a list with a component named (or shortened to) cluster which is a vector of length `n = nrow(x)` of integers in `1:k` determining the clustering or grouping of the `n` observations. The default value is the following function, which wraps partitioning around medoids, `pam`: `function(x, k){list(cluster = pam(x, k, cluster.only=TRUE))}` Any function that has these input/output properties (performing a clustering) will suffice. The more appropriate the clustering method, the better chance your gap statistic results will be useful.
`K.max` | (Optional). A single positive integer value. It indicates the maximum number of clusters that will be considered. Value must be at least two. This is passed to `clusGap`.
`...` | (Optional). Additional named parameters passed on to `clusGap`. For example, the `method` argument provides for extensive options regarding the method by which the “optimal” number of clusters is computed from the gap statistics (and their standard deviations). See the `clusGap` documentation for more details.

### Value

An object of S3 class `"clusGap"`, basically a list with components. See the `clusGap` documentation for more details.

### Examples

    data("soilrep")
    sord  = ordinate(soilrep, "PCoA", "bray")
    # Evaluate axes with scree plot
    plot_scree(sord)
    # Gap Statistic
    gs = gapstat_ord(sord, axes=1:3, verbose=FALSE)
    # plot_ordination(soilrep, sord,  color="Treatment")
    plot_clusgap(gs)
    print(gs, method="Tibs2001SEmax")

[Package phyloseq version 1.28.0 Index]