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

[Ben Tupper]

Hi,

In the short term you could use raster::alignExtent() to get align bio5 to the the extent of lg5.  

I would also inspect the source of your data and compare it to your locally stored copy of it.  If they are different then it would be worthwhile to review the steps you used to download, manipulate and store it.

Cheers,
Ben 

 
> On Mar 15, 2017, at 1:21 PM, Vijay Ramesh via R-sig-Geo <r-sig-geo at r-project.org> wrote:
> 
> I re-checked the original extent and here it is: This is data obtained from
> WorldClim.
> 
>> bio5
> class       : RasterLayer
> dimensions  : 3600, 8640, 31104000  (nrow, ncol, ncell)
> resolution  : 0.04166667, 0.04166667  (x, y)
> extent      : -180, 180, -60, *90.00001 * (xmin, xmax, ymin, ymax) #This
> varies at the 6th decimal place.
> coord. ref. : +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs
> data source : C:\Users\rameshv\Downloads\Climate
> Stability\Data_LGM_Present\Present\1_RawData\bio_5
> names       : bio_5
> values      : -86, 489  (min, max)
> attributes  :
>        ID COUNT
> from: -86     1
> to  : 489    38
> 
> 
>> lg5
> class       : RasterLayer
> dimensions  : 3600, 8640, 31104000  (nrow, ncol, ncell)
> resolution  : 0.04166667, 0.04166667  (x, y)
> extent      : -180, 180, -60, 90  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs
> data source : C:\Users\rameshv\Downloads\Climate
> Stability\Data_LGM_Present\LGM\1_RawData\cclgmbi5.tif
> names       : cclgmbi5
> values      : -204, 519  (min, max)
> 
> What do you suggest?
> 
> Also, any suggestions on aligning them before I crop them? I wouldn't want
> to projectRaster using one of the rasters, as that creates extra number of
> rows (when I coerce the raster to a Spatial Pixels Data Frame).
> 
> 
> 
> On Wed, Mar 15, 2017 at 1:13 PM, Sarah Goslee <sarah.goslee at gmail.com>
> wrote:
> 
>> 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
>> 
> 
> 
> 
> -- 
> Data Manager,
> Barbara Han Lab,
> Cary Institute of Ecosystem Studies,
> 2801 Sharon Turnpike, Millbrook, NY 12545
> Lab Site : http://www.hanlab.science/
> Personal Site : http://evolecol.weebly.com/
> Phone : (845)-677-7600 Ext: 241
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org