frag.cohesion.ranking: Rank a series of spatial units by comparing their cohesion...

In archeofrag: Spatial Analysis in Archaeology from Refitting Fragments

Rank a series of spatial units by comparing their cohesion values

Description

Rank a series of spatial units based on how many times they feature the highest cohesion value in pairwise comparisons.

Usage

frag.cohesion.ranking(cohesion.df, add.math.signs=TRUE)

Arguments

cohesion.df	Matrix or data.frame, with two columns for the cohesion values for each pair of spatial units and spatial units labesl in row names.
add.math.signs	Boolean. Wheter adding or not (in)equality signs.

Details

Cohesion values computed with the frag.layers.cohesion() are relative to the pair of spatial units under consideration and do not allow for comparison of more than two spatial units. The frag.cohesion.ranking function offers a method to analyse larger series of spatial units.

Given the cohesion values computed for more than two spatial units, it counts how many times each spatial unit features the highest cohesion value in pairwise comparisons. Spatial units are sorted based on this count.

By default, the function's output is formated for human reading, adding equality and inequality signs in the series of spatial units labels to help in interpeting it. This enhancement can be disabled with add.math.signs=FALSE.

The matrix or data frame given to the cohesion.df parameter must be formated as an output of the frag.layers.cohesion() function. Namely, each row corresponds to the comparison of two spatial units, the two columns include the corresponding cohesion values, and the row name gives the labels of the spatial units (separated by the sign '/').

Value

If add.math.signs=TRUE, a data frame inclduding (in)equality signs and empty values. Else, a named numeric vector.

Author(s)

Sebastien Plutniak <sebastien.plutniak at posteo.net>

See Also

frag.layers.cohesion

Examples

g1 <- frag.simul.process(n.components=5,  vertices=20, disturbance=.1)
g2 <- frag.simul.process(n.components=10, vertices=90, disturbance=.03)

# assign different names for these spatial units:
igraph::V(g2)$layer <- as.character(factor(igraph::V(g2)$layer, labels = c(3, 4))) 
igraph::V(g2)$name <- paste0(igraph::V(g2)$name, "g2")

g <- igraph::disjoint_union(g1, g2) # merge the graphs
g$frag_type <- "cr" # this value was lost while merging

cohesion.res <- frag.layers.cohesion(g, layer.attr="layer", verbose=FALSE) # compute cohesions
frag.cohesion.ranking(cohesion.res, add.math.signs = TRUE) # rank the spatial units

archeofrag documentation built on April 22, 2026, 9:07 a.m.