Subsample a dataset

subsample() creates a smaller version of the original dataset by sampling its rows. Because PCOs should be computed on the full dataset and most other functions take in regions_pco objects, subsample() requires a regions_pco object as its input.

Usage

subsample(pco, sample = NULL, type = "seq")

Arguments

pco

a regions_pco object; the output of a call to svdPCO().

sample

numeric; either the number or proportion of vertebrae to remain the sampled dataset. If NULL, the original dataset is returned.

type

string; the type of subsampling to do, either "seq" for sampling in sequence or "random" for random sampling. Default is "seq". Abbreviations allowed.

Value

A regions_pco object, a subset of the original supplied to pco. The original dataset is stored as an attribute, which itself contains the subsampling indices.

See also

svdPCO(), process_measurements(), plotvertmap() to visualize the vertebral map after subsampling.

Examples

data("alligator")

alligator_data <- process_measurements(alligator,
                                       pos = "Vertebra")

# Compute PCOs
alligator_PCO <- svdPCO(alligator_data)

# Plot vertebrae before subsampling
plotvertmap(alligator_PCO, dropNA = FALSE,
            text = TRUE)


# Subsample data after estimating PCOs; subsample down
# to 15 vertebrae
alligator_PCO_sample <- subsample(alligator_PCO,
                                  sample = 15)

# Plot vertebrae after subsampling; gray vertebrae
# have been dropped
plotvertmap(alligator_PCO_sample, dropNA = FALSE,
            text = TRUE)