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

Merge multiple SpatRasters to create a new SpatRaster object 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 a also a method for merging SpatVector with a data.frame; that is, to join the data.frame to the attribute table of the SpatVector.

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

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

# S4 method for 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> <int> <num>
#>  values      : Diekirch Clervaux     1     1   312 18081   993
#>                Diekirch Diekirch     1     2   218 32543   493
#>                Diekirch  Redange     1     3   259 18664   282
values(pm)
#>          NAME_1           NAME_2 ID_1 ID_2 AREA    POP Value
#> 1      Diekirch         Clervaux    1    1  312  18081   993
#> 2      Diekirch         Diekirch    1    2  218  32543   493
#> 3      Diekirch          Redange    1    3  259  18664   282
#> 4      Diekirch          Vianden    1    4   76   5163   967
#> 5      Diekirch            Wiltz    1    5  263  16735   694
#> 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