[GIS] Using the same mask on two rasters, but I get different extents in R

climatemaskingrrasterrgdal

I loaded a shapefile in R, and cropped and masked it with the same mask, but I get different extents. Any suggestions?

Code below:

library(raster)
library(rgdal)
library(GISTools)
library(sp)
library(maptools)

##Loading the first mask
Mask <- readOGR("C:\\Users\\rameshv\\Downloads\\Climate Stability\\SPV_Mask\\mask.shp")
proj4string(Mask) <- CRS("+init=epsg:4326")

#Loading the Rasters For Present and LGM and clipping them to the right extent
bio5 <- raster("C:\\Users\\rameshv\\Downloads\\Climate Stability\\Data_LGM_Present\\Present\\1_RawData\\bio_5")
proj4string(bio5) <- CRS("+init=epsg:4326")
lg5 <- raster("C:\\Users\\rameshv\\Downloads\\Climate Stability\\Data_LGM_Present\\LGM\\1_RawData\\cclgmbi5.tif")
proj4string(lg5) <- CRS("+init=epsg:4326")

##Cropping by using the Crop and Mask functions
cr<- crop(bio5, extent(Mask))
bio5 <- mask(cr, Mask)

cr2<- crop(lg5, extent(Mask))
lg5<- mask(cr2, Mask)

> bio5
 class       : RasterLayer 
 dimensions  : 339, 246, 83394  (nrow, ncol, ncell)
 resolution  : 0.04166667, 0.04166667  (x, y)
 extent      : 72.45835, 82.70835, 8.083337, 22.20834  (xmin, xmax, ymin, ymax)
 coord. ref. : +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
 data source : in memory
 names       : bio_5 
 values      : 207, 432  (min, max)
 attributes  :
    ID COUNT
 from: -86     1
 to  : 489    38

 > lg5
 class       : RasterLayer 
 dimensions  : 339, 246, 83394  (nrow, ncol, ncell)
 resolution  : 0.04166667, 0.04166667  (x, y)
 extent      : 72.45833, 82.70833, 8.083333, 22.20833  (xmin, xmax, ymin, ymax)
 coord. ref. : +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
 data source : in memory
 names       : cclgmbi5 
 values      : 187, 392  (min, max)

EDIT

Following a projection, I am able to align extents of the rasters, however, if I coerce them to a vector, I am getting differences in number of elements. Any thoughts?

new.lg5 <- projectRaster(lg5,bio5)

x <- as(bio5,"SpatialPixelsDataFrame")
y <- as(new.lg5, "SpatialPixelsDataFrame")

> str(x)
 Formal class 'SpatialPixelsDataFrame' [package "sp"] with 7 slots
  ..@ data       :'data.frame': 54202 obs. of  1 variable:

> str(y)
  Formal class 'SpatialPixelsDataFrame' [package "sp"] with 7 slots
  ..@ data       :'data.frame': 54747 obs. of  1 variable:

Best Answer

You could try this: 

library(raster)
new.lg5 <- projectRaster(lg5, bio5)

This will use the projection of one of your layers and applies it to the others, but it also sets the extent of a raster file.

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