Merge SpatRasters, or merge a SpatVector with a data.frame

Merge multiple SpatRasters to create a new SpatRaster with a larger spatial extent. The SpatRasters must have the same origin and spatial resolution. In areas where the SpatRasters overlap, the values of the SpatRaster that is first in the sequence of arguments (or in the SpatRasterCollection) will be retained (unless first=FALSE). Cells that are NA are ignored unless na.rm=FALSE

There is also a method for merging SpatVector with a data.frame; that is, to join the data.frame to the attribute table of the SpatVector.

Usage

# S4 method for class 'SpatRaster,SpatRaster'
merge(x, y, ..., first=TRUE, na.rm=TRUE, filename="", overwrite=FALSE, wopt=list())

# S4 method for class 'SpatRasterCollection,missing'
merge(x, first=TRUE, na.rm=TRUE, filename="", ...)

# S4 method for class 'SpatVector,data.frame'
merge(x, y, ...)

Arguments

x

SpatRaster, SpatRasterCollection, or SpatVector

y

missing if x is a SpatRasterCollection. SpatRaster if x is a SpatRaster. data.frame if x is a SpatVector

...

if x is a SpatRaster: additional objects of the same class as x. If x is a SpatRasterCollection: options for writing files as in writeRaster. If x is a SpatVector, the same arguments as in merge

first

logical. If TRUE, in areas where rasters overlap, the first value is used. Otherwise the last value is used

na.rm

logical. If TRUE values that are NA are ignored

filename

character. Output filename

overwrite

logical. If TRUE, filename is overwritten

wopt

list with named options for writing files as in writeRaster

Value

SpatRaster or SpatVector

See also

Combining tiles with vrt may be more efficient than using merge. See mosaic for averaging overlapping regions.

See classify to merge a SpatRaster and a data.frame and union to combine SpatExtent objects.

Examples

x <- rast(xmin=-110, xmax=-80, ymin=40, ymax=70, res=1, vals=1)
y <- rast(xmin=-85, xmax=-55, ymax=60, ymin=30, res=1, vals=2)
z <- rast(xmin=-60, xmax=-30, ymax=50, ymin=20, res=1, vals=3)

m1 <- merge(x, y, z)
m2 <- merge(z, y, x)
m3 <- merge(y, x, z)

# if you have many SpatRasters, it may be convenient
# to make a SpatRasterCollection
rlist <- list(x, y, z)
rsrc <- sprc(rlist)

m <- merge(rsrc)


## SpatVector with data.frame
f <- system.file("ex/lux.shp", package="terra")
p <- vect(f)
dfr <- data.frame(District=p$NAME_1, Canton=p$NAME_2, Value=round(runif(length(p), 100, 1000)))
dfr <- dfr[1:5, ]
pm <- merge(p, dfr, all.x=TRUE, by.x=c('NAME_1', 'NAME_2'), by.y=c('District', 'Canton'))
pm
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 12, 7  (geometries, attributes)
#>  extent      : 5.74414, 6.528252, 49.44781, 50.18162  (xmin, xmax, ymin, ymax)
#>  coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#>  names       :   NAME_1   NAME_2  ID_1  ID_2  AREA       POP Value
#>  type        :    <chr>    <chr> <num> <num> <num>     <num> <num>
#>  values      : Diekirch Clervaux     1     1   312 1.808e+04   433
#>                Diekirch Diekirch     1     2   218 3.254e+04   961
#>                Diekirch  Redange     1     3   259 1.866e+04   922
values(pm)
#>          NAME_1           NAME_2 ID_1 ID_2 AREA    POP Value
#> 1      Diekirch         Clervaux    1    1  312  18081   433
#> 2      Diekirch         Diekirch    1    2  218  32543   961
#> 3      Diekirch          Redange    1    3  259  18664   922
#> 4      Diekirch          Vianden    1    4   76   5163   841
#> 5      Diekirch            Wiltz    1    5  263  16735   388
#> 6  Grevenmacher       Echternach    2    6  188  18899    NA
#> 7  Grevenmacher           Remich    2    7  129  22366    NA
#> 8  Grevenmacher     Grevenmacher    2   12  210  29828    NA
#> 9    Luxembourg         Capellen    3    8  185  48187    NA
#> 10   Luxembourg Esch-sur-Alzette    3    9  251 176820    NA
#> 11   Luxembourg       Luxembourg    3   10  237 182607    NA
#> 12   Luxembourg           Mersch    3   11  233  32112    NA