如何合并每个 ID 的波段以在 R 中创建两个多波段 TIFF？

Question

我有 16 个单独的光栅文件，分别以 ID 和波段命名，用于 8 个波段和 2 个 ID。如何合并每个 ID 的波段以创建两个多波段 TIFF？这是我的数据：

    dput(rastlist)
    c("7398_b10_new.tif", "7398_b2_clip.tif", "7398_b3_clip.tif", 
"7398_b4_clip.tif", "7398_b5_clip.tif", "7398_b6_clip.tif", "7398_b7_clip.tif", 
"7398_pan_new.tif", "9609_b10_new.tif", "9609_b2_clip.tif", "9609_b3_clip.tif", 
"9609_b4_clip.tif", "9609_b5_clip.tif", "9609_b6_clip.tif", "9609_b7_clip.tif", 
"9609_pan_new.tif")

我设法为列表的前 8 个元素做到了这一点。方法如下：

setwd("mydir")

#first import all files in a single folder as a list 
rlist <- list.files(path = "mydir", pattern='.tif$', all.files=T, full.names=F)

#substract the  first 8 raster of the list
n = tail(rlist,8)

#stack layers
rstack = stack(n)

#substract the first element of the list
one = tail(n, 1)

#get the first 4 letters of the first element of a list (to be used as raster name of the raster stack)
rexport = substr(one, 1, 4)

writeRaster(rstack, filename = rexport, options = "INTERLEAVE=BAND", overwrite = T, format = "GTiff")

基本上，我想要的是创建一个函数，每 8 个栅格执行一次上述代码。

Answer 1

循环遍历每个唯一 ID：

for(ras in unique(substr(rastlist, 1, 4))){
  rlist <- list.files(path = "mydir", pattern=paste0(ras, '*.tif$'), all.files=T, full.names=F)
  rstack = stack(rlist)
  writeRaster(rstack, filename = paste0(ras, ".tif"), options = "INTERLEAVE=BAND", overwrite = T, format = "GTiff")
}

或者，同样的事情，但作为一个函数，就像你在问题中所说的那样：

stacker <- function(ras){
  rlist <- list.files(path = "mydir", pattern=paste0(ras, '*.tif$'), all.files=T, full.names=F)
  rstack = stack(rlist)
  writeRaster(rstack, filename = rexport, options = "INTERLEAVE=BAND", overwrite = T, format = "GTiff")
}

rass <- unique(substring(rastlist, 1, 4))

lapply(rass, stacker)