cendist: Compute distances from centroid

In olobiolo/centroidr: Find Centroid of a Set of Points in n-dimensional Space

Description

Generic function that, given a set of pionts, finds distances between them and their centroid. Calls centroid and euclidean.

Usage

cendist(x, ...)

## S3 method for class 'numeric'
cendist(x, ...)

## S3 method for class 'matrix'
cendist(x, ...)

## S3 method for class 'data.frame'
cendist(x, ...)

## S3 method for class 'grouped_df'
cendist(x, ...)

Arguments

x	numeric vector, matrix or data frame
...	for data frame method, columns that store cooridinates

Details

A set of coordinates in n-dimensional space can be provided as a matrix or a data frame with points listed in rows and dimensions listed in columns (see Column specification). First the centroid coordinates is found by centroid and then the point-centroid distances are computed by euclidean.

Value

numeric vector of distances

Methods (by class)

• numeric: returns deviations from the mean

• matrix: finds the centroid and applies the catresian function across the matrix rows; if x only has one column, drops dimensions and calls vector method

• data.frame: extracts the requested columns and converts them to a matrix and then calls the matrix method

• grouped_df: see data.frame__to__grouped_df

Special cases

For a 1-dimensional set (one column matrix) deviations from the mean are returned.

For a single point (one row matrix) expect Value to be 0.

Any missing coordinates (NAs) will derail distance calculation for that point.

Column specification

Matrices are accepted as is, all columns are considered. If x is a data frame, columns that carry coordinates may be specified. They can be given as strings, bare names or numerical indices but they must all be specified in the same way. Also, each column must be specified separately, vectors are not accepted. If no columns are specified, all numeric ones are considered.

olobiolo/centroidr documentation built on Dec. 3, 2019, 12:55 p.m.