根据土地覆盖类别计算r中的p值（t检验）

Question

我有3个栅格：

> Observedraster
class      : RasterLayer 
dimensions : 2803, 5303, 14864309  (nrow, ncol, ncell)
resolution : 0.008333333, 0.008333333  (x, y)
extent     : 60.85, 105.0417, 15.95833, 39.31667  (xmin, xmax, ymin, ymax)
crs        : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
source     : memory
names      : A1 
values     : 0, 20(min, max)

> Modelledraster
class      : RasterLayer 
dimensions : 47, 89, 4183  (nrow, ncol, ncell)
resolution : 0.5, 0.5  (x, y)
extent     : 60.75, 105.25, 15.75, 39.25  (xmin, xmax, ymin, ymax)
crs        : NA 
source     : C:/Users/XXX.tif 
names      : agbmpi 
values     : 0, 18.852  (min, max)

Landcover raster
class      : RasterLayer 
dimensions : 2803, 5303, 14864309  (nrow, ncol, ncell)
resolution : 0.008333333, 0.008333333  (x, y)
extent     : 60.85, 105.0417, 15.95833, 39.31667  (xmin, xmax, ymin, ymax)
crs        : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
source     : C:/Users/XXXX/landusemaskedme.tif 
names      : landusemaskedme 
values     : 1, 12  (min, max)

我想知道如何根据土地覆盖类型计算Observedraster和Modelledraster之间的t检验（p值）？

示例数据：

raster1 <-  raster(matrix(c(1,1,1,2,3,4,5,6,7),ncol =3))

raster2 <- raster(matrix(c(1,1,1,2,2,2,3,3,3),ncol =3))
raster2 <- as.factor(raster2)

rat <- levels(raster2 )[[1]]
rat[["landcover"]] <- c("land","ocean/lake", "rivers")
levels(raster2 ) <- rat