我有 175 个 tif 文件,包括全球(陆地)各种作物的网格数据。我想创建一个仅包含最高值索引的栅格数据集。这样对于每个单元格,我都知道哪种作物具有最高的价值。
我的代码有效。但如果我运行 calc() 函数,有时会出现无法解释的错误:
Error in .calcTest(x[1:5], fun, na.rm, forcefun, forceapply) : cannot use this function. Perhaps add '...' or 'na.rm' to the function arguments?
library(raster)
# Get the file names for later import
file_list <- list.files(path = "C:/folder/test", full.names = TRUE)
filtered_file_list <- file_list[grep("HarvestedAreaFraction.tif",file_list,fixed=TRUE)]
#init
raster_stack <- stack()
crop_names <- character() #list to save the index of crops
for (file_path in filtered_file_list){
raster_layer <- raster(file_path)
# Aggregate the raster to a 1-degree resolution, all tif-files have the same resolution
aggregated_raster_layer <- aggregate(raster_layer, fact=c(12,12), fun=mean)
raster_layer <- na.omit(aggregated_raster_layer)
raster_stack <- addLayer(raster_stack, raster_layer)
crop_name <- gsub(".*/(.*?)_HarvestedAreaFraction\\.tif$", "\\1", file_path)
crop_names <- c(crop_names, crop_name)
}
# Function to get the name of the crop with the maximum fraction
get_max_crop_name <- function(x, na.rm = TRUE, ...) {
max_index <- which.max(x)
# max_name <- crop_names[max_index]
if (length(max_index) == 0 || all(x == 0) || all(is.na(x))) {
max_name <- 0
} else {
max_name <- max_index
}
return(max_name)
}
max_crop_raster <- calc(raster_stack, fun=get_max_crop_name, na.rm=TRUE)
仅当我导入较大的 tif 文件时才会出现该错误。在 175 个文件中,大约有 100 个文件大小约为 30MB,其他文件大小约为 2-3MB。它对于较小的文件工作得很好,但是一旦我包含其中一个较大的文件,我就会收到此错误
有什么想法吗?
这不起作用的原因是你的函数不是向量化,因为
if
语句一次只能计算一个值。wich.max
。像这样(用“terra”代替“raster”):
library(terra)
ff <- list.files(path = "C:/folder/test", full.names = TRUE, pattern="HarvestedAreaFraction.tif")
x <- rast(ff)
mxcrop <- which.max(x)