SpatialPoints.Rdcreate objects of class SpatialPoints-class or
SpatialPointsDataFrame-class from
coordinates, and from coordinates and data.frames
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)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
projection string of class CRS-class
bounding box matrix, usually NULL and constructed from the data, but may be passed through for coercion purposes if clearly needed
object of class data.frame; the number of rows in data
should equal the number of points in the coords object
numeric; if present, records the column positions where
in data the coordinates were taken from (used by coordinates<-)
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.
SpatialPoints returns an object of class SpatialPoints;
SpatialPointsDataFrame returns an object of class SpatialPointsDataFrame;
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
#> Warning: forming a SpatialPointsDataFrame based on maching IDs, not on record order. Use match.ID = FALSE to match on record order
#> coordinates a
#> a (1, 1) 5
#> b (2, 2) 4
#> c (3, 3) 3
#> d (4, 4) 2
#> e (5, 5) 1
SpatialPointsDataFrame(pts, df, match.ID = TRUE) # don't warn
#> coordinates a
#> a (1, 1) 5
#> b (2, 2) 4
#> c (3, 3) 3
#> d (4, 4) 2
#> e (5, 5) 1
SpatialPointsDataFrame(pts, df, match.ID = FALSE) # don't warn
#> coordinates a
#> e (1, 1) 1
#> d (2, 2) 2
#> c (3, 3) 3
#> b (4, 4) 4
#> a (5, 5) 5
df$m = letters[5:1]
SpatialPointsDataFrame(pts, df, match.ID = "m") # don't warn
#> coordinates a m
#> a (1, 1) 5 a
#> b (2, 2) 4 b
#> c (3, 3) 3 c
#> d (4, 4) 2 d
#> e (5, 5) 1 e
dimnames(pts)[[1]] = letters[5:1]
SpatialPointsDataFrame(pts, df) # don't warn: ID matching doesn't reorder
#> coordinates a m
#> e (1, 1) 1 e
#> d (2, 2) 2 d
#> c (3, 3) 3 c
#> b (4, 4) 4 b
#> a (5, 5) 5 a