ssm.compositionality {cultevo}

Find a segmentation that maximises the overall string coverage across all signals.

Description

This algorithm builds on Spike's measure of compositionality (see sm.compositionality), except instead of simply determining which segment(s) have the highest mutual predictability for each meaning feature separately, it attempts to find a combination of non-overlapping segments for each feature that maximises the overall string coverage over all signals. In other words, it tries to find a segmentation which can account for (or 'explain') as much of the string material in the signals as possible.

Usage

ssm.compositionality(x, y, groups = NULL)

ssm.segmentation(x, y, mergefeatures = FALSE, verbose = FALSE)

Arguments

x

a list or vector of character sequences

y

a matrix or data frame with as many rows as there are strings (see section Meaning data format)

groups

a list or vector with as many items as strings, used to split the signals and meanings into data sets for which the compositionality measures are computed separately.

mergefeatures

logical: if TRUE, ssm.segmentation will try to improve on the initial solution by incrementally merging pairs of meaning features as long as doing so improves the overall string coverage of the segmentation.

verbose

logical: if TRUE, messages detailed information about the number of segment combinations considered for every coverage computed.

Details

For large data sets and long strings, this computation can get very slow. If the attested signals are such that no perfect segmentation is possible, this algorithm is not guaranteed to find any segmentation (as no such segmentation might exist).

See Also

sm.compositionality

Examples

ssm.segmentation(c("as", "bas", "basf"),
  cbind(a=c(TRUE, FALSE, TRUE), b=c(FALSE, TRUE, TRUE)))


# signaling system where one meaning distinction is not encoded in the signals
print(threebytwoanimals <- enumerate.meaningcombinations(list(animal=c("dog", "cat", "tiger"),
  colour=c("col1", "col2"))))

ssm.segmentation(c("greendog", "bluedog", "greenfeline", "bluefeline", "greenfeline", "bluefeline"),
  threebytwoanimals)

# the same analysis again, but allow merging of features
ssm.segmentation(c("greendog", "bluedog", "greenfeline", "bluefeline", "greenfeline", "bluefeline"),
  threebytwoanimals, mergefeatures=TRUE)