nearest_point: Function to select nearest community to a given sampling...

In validmeasures/spatialsampler: An Implementation of the Centric Systematic Area Sampling (CSAS) and Simple Spatial Sampling Method (S3M) sampling approaches in R

Description

Function to select nearest community to a given sampling point (usually the centroid of a square grid for CSAS or of a hexagonal grid for S3M)

Usage

nearest_point(data, x1, y1, query, x2, y2, n = 1, duplicate = FALSE)

Arguments

data	A matrix or data frame of input sampling locations to which nearest village locations are to be matched. Data frame should contain at least information on longitude and latitude coordinates
x1	A character value specifying the variable name in input holding the longitude information of the sampling locations
y1	A character value specifying the variable name in input holding the latitude information of the sampling locations
query	A data frame of village/community locations with at least information on longitude and latitude coordinates from which to query for nearest point
x2	A character value specifying the variable name in query holding the longitude information of the village/community locations
y2	A character value specifying the variable name in query holding the latitude information of the village/community locations
n	Number of nearest village/community locations to select. Default is 1
duplicate	Logical. If TRUE, keep duplicate samples. If FALSE, remove duplicate samples.

Value

A data frame of selected nearest sampling village/community locations

Author(s)

Farah Mohamad Ibrahim <[e-mail]>

Examples

# Use nearest_point() with test sampling points in Sennar
sennar <- subset(sudan01, STATE == "Sennar")
samp.points <- sp::spsample(sennar, type = "hexagonal", n = 20)
nearest_point(data = samp.points@coords, x1 = "x", y1 = "y",
              query = sennar_villages, x2 = "x", y2 = "y",
              n = 3)

validmeasures/spatialsampler documentation built on Oct. 16, 2021, 3:15 a.m.