[R-sig-Geo] Same mask for two rasters, but obtaining different extents in R

[Sarah Goslee]

The most likely explanation seems to me that the rasters were not
aligned before cropping, so they are not aligned after cropping.

Have you checked the original extent and resolution?

Sarah

On Tue, Mar 14, 2017 at 5:31 PM, Vijay Ramesh via R-sig-Geo
<r-sig-geo at r-project.org> wrote:
> 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)
>
>

-- 
Sarah Goslee
http://www.functionaldiversity.org