SpatialPoints: create objects of class SpatialPoints or...

In sp: Classes and Methods for Spatial Data

create objects of class SpatialPoints or SpatialPointsDataFrame

Description

create objects of class SpatialPoints-class or SpatialPointsDataFrame-class from coordinates, and from coordinates and data.frames

Usage

 
SpatialPoints(coords, proj4string=CRS(as.character(NA)), bbox = NULL)
SpatialPointsDataFrame(coords, data, coords.nrs = numeric(0), 
      proj4string = CRS(as.character(NA)), match.ID, bbox = NULL)

Arguments

coords	numeric matrix or data.frame with coordinates (each row is a point); in case of SpatialPointsDataFrame an object of class SpatialPoints-class is also allowed
proj4string	projection string of class CRS-class
bbox	bounding box matrix, usually NULL and constructed from the data, but may be passed through for coercion purposes if clearly needed
data	object of class data.frame; the number of rows in data should equal the number of points in the coords object
coords.nrs	numeric; if present, records the column positions where in data the coordinates were taken from (used by coordinates<-)
match.ID	logical or character; if missing, and coords and data both have row names, and their order does not correspond, matching is done by these row names and a warning is issued; this warning can be suppressed by setting match.ID to TRUE. If TRUE AND coords has non-automatic rownames (i.e., coerced to a matrix by as.matrix, dimnames(coords)[[1]] is not NULL), AND data has row.names (i.e. is a data.frame), then the SpatialPointsDataFrame object is formed by matching the row names of both components, leaving the order of the coordinates in tact. Checks are done to see whether both row names are sufficiently unique, and all data are matched. If FALSE, coordinates and data are simply "glued" together, ignoring row names. If character: indicates the column in data with coordinates IDs to use for matching records. See examples below.

Value

SpatialPoints returns an object of class SpatialPoints; SpatialPointsDataFrame returns an object of class SpatialPointsDataFrame;

See Also

coordinates, SpatialPoints-class, SpatialPointsDataFrame-class

Examples

set.seed(1331)
pts = cbind(1:5, 1:5)
dimnames(pts)[[1]] = letters[1:5]
df = data.frame(a = 1:5)
row.names(df) = letters[5:1]

library(sp)
options(warn=1) # show warnings where they occur
SpatialPointsDataFrame(pts, df) # warn
SpatialPointsDataFrame(pts, df, match.ID = TRUE) # don't warn
SpatialPointsDataFrame(pts, df, match.ID = FALSE) # don't warn
df$m = letters[5:1]
SpatialPointsDataFrame(pts, df, match.ID = "m") # don't warn

dimnames(pts)[[1]] = letters[5:1]
SpatialPointsDataFrame(pts, df) # don't warn: ID matching doesn't reorder

sp documentation built on May 29, 2024, 5:33 a.m.