我有一个栅格,我想检查带有值的像元是否与我的关注区域重叠,这是一个空间多边形文件。
有快速的方法吗?
我的栅格看起来像这样:
我试过的
r <- raster("C:/user/test.jp2")
studyarea <- readOGR("C:/user/boundary.shp")
dummi <- as(extent(r), "SpatialPolygons")
if (gContainsProperly(studyarea, dummi)) {
print("Raster extent is fully within the Area of interest")
}
else if (gIntersects(studyarea, dummi)) {
print("Raster extent is not fully within the Area of interest")
} else {
print("Raster extent is fully outside the Area of interest")
}
as(extent(r), "SpatialPolygons")
在值以及NA中创建一个多边形。但是我只想检查值部分和学习区域是否重叠
栅格和学习区域的数据示例:
matrix <- matrix(c(NA,NA,NA,1,NA,NA,2,1,NA,1,3,4,2,3,4,1), nrow=4)
r <- raster(matrix)
extent(r) <- c(399960, 509760, 5290200, 5400000)
crs(r) <- "+proj=utm +zone=32 +datum=WGS84 +units=m +no_defs"
writeRaster(r, paste(getwd(),"filename.jp2"))
matrix <- matrix(c(1,1,NA,NA,1,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA), nrow=4)
rpoly<- raster(matrix)
extent(rpoly) <- c(399960, 509760, 5290200, 5400000)
crs(rpoly) <- "+proj=utm +zone=32 +datum=WGS84 +units=m +no_defs"
studyarea <- rasterToPolygons(rpoly)
谢谢
我找到了更快的解决方案。可以通过多边形裁剪栅格,然后可以通过多边形遮蔽栅格。如果“多边形”区域中没有栅格值。栅格将具有最小值= 0和最大值= 0。
建立资料
matrix <- matrix(c(NA,NA,NA,1,NA,NA,2,1,NA,1,3,4,2,3,4,1), nrow=4)
r <- raster(matrix)
extent(r) <- c(399960, 509760, 5290200, 5400000)
crs(r) <- "+proj=utm +zone=32 +datum=WGS84 +units=m +no_defs"
writeRaster(r, paste(getwd(),"filename.jp2"))
matrix <- matrix(c(1,1,NA,NA,1,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA), nrow=4)
rpoly<- raster(matrix)
extent(rpoly) <- c(399960, 509760, 5290200, 5400000)
crs(rpoly) <- "+proj=utm +zone=32 +datum=WGS84 +units=m +no_defs"
studyarea <- rasterToPolygons(rpoly)
解
# Reproject. Make sure both have the same projection
studyarea <- spTransform(studyarea, projection(r))
# Crop and clip raster with study area polygon
r_crop <- crop(r, studyarea)
r_mask <- mask(r_crop, studyarea, updatevalue = NA, updateNA= TRUE)
if (r_mask@data@min == 0 && r_mask@data@max == 0){
print("raster and studyarea do not overlap))
}
else {
print("Raster and studyarea do overlap")
}
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