我是R的新手，有这个问题：

if（type ==“xls”）{：缺少值需要TRUE / FALSE时出错

我有这个代码，我不知道问题是什么：

for (i in 1:length(data))
{ 
  setwd("D:\\Baltoro\\Landsat_2017\\Shape_area")
  Shape = shapefile(data[i])
  filename = file[i]

    for (ii in 1:14)
  { 
    area = shapefile(name_area[ii])
    trans = spTransform(area, CRS("+proj=utm +zone=43 +ellps=WGS84"))
    Shape1 = crop(Shape,trans)
    name = sapply(filename, FUN=function(k) paste0(k, "_", ii, ".xlsx"))

    if (is.na(Shape1))
    { 
      print(name)
     print("empty")
     }

   else
    {
    Shape1$area_sqm = area(Shape1)
    Table = Shape1$area_sqm
    setwd("D:\\Baltoro\\Auswertung\\Detail_2017")
    write.xlsx(Table, file=name[i])
    print(name)
    print("done")
    }
  }
}
r