I aim to combine biodiversity data with land cover information (rasters and vectors). However, I need to match the resolution, extent, CRS, and dimensions of each raster (predictor variables) with my biodiversity data (answer variables). I had succeed to do it individually but there are six rasters. Although, when I try a loop for the raster stack. I got some errors.
library(terra)
library(raster)
#Create a raster stack with land cover predictors:
CDI_stack<-raster::stack(list.files(path = dir_Proj1, pattern='.tif', full.names=T))
#Convert to cylindrical equal area projection
equalareaproj<-" proj=cea lon_0=0 lat_ts=30 x_0=0 y_0=0 datum=WGS84 units=m no_defs"
crs(CDI_stack, warn=FALSE)<-equalareaproj
#Raster with standard dimension, resolution, extention and CRS
standard<-terra::subset(study_area, 2)
#Loop for the raster stack
for(i in 1:length(CDI_stack@layers)){
#Creating a single raster with each layer to maintain values
CDI_layer<-terra::rast(terra::subset(CDI_stack, i))
#Matching a raster extention individually
CDI_layer<-ext(standard)
#Cropping it with standard raster to reduce matching error
raster::crop(CDI_layer[i],standard)
#Resample resolution
terra::resample(CDI_layer[i], standard, method= "near", threads= T)
#Write the raster:
return(writeRaster(Resampled_layer,
filename=paste0("~/Land use/Chronic_Anthropogenic_Disturbance_Surface/", CDI_layer[i]),
format="GTiff", overwrite=TRUE))
}
I found these errors:
Error in h(simpleError(msg, call)) :
error evaluating argument 'x' in method selection for function 'crop': 'this S4 class is not subsettable
Error in (function (classes, fdef, mtable) :
unable to find an inherited method for function ‘crop’ for signature ‘"numeric"’
I would like to know if there's any complication to use raster stack or whether I am doing any code step wrongly. I expect to found the correction on the code or of the use of class object.
Please, I hope for your support. Thank you! G.
CodePudding user response:
It should be easy enough to find out what is going wrong when you run the code line by line; including inside the for-loop (set i
to 1 or whatever the valye is when the error occurs).
You will see that this fails:
CDI_layer <- ext(standard)
raster::crop(CDI_layer[i],standard)
Because CDI_layer[i]
is a single number.
There are other things that are awkward. Especially, just use "terra", do not also use "raster" at the same time to avoid confusion.
CodePudding user response:
Thank you for your advices, Mr. Hijimanns. I found too many errors. I preferred to work with a list from the raster stack than the stack, it worked better in the loop. Also, I used a vector to crop the raster, it preserved raster values (avoiding return NA).
#Create a list from the stack with land cover predictors:
CDI_list<-terra::as.list(CDI_stack)
rm(study_area,CDI_stack)
#Create a list to store the results
results <- list()
#Loop for each SpatRaster from the list
for(i in 1:length(CDI_list)) {
r<-rast(CDI_list[[i]]) # create a raster for each layer
ext(r) <-ext(standard) # redefine extension for each layer
#Crop rasters using the vector to avoid 'NA' values
rc <- terra::crop(r, standard_vec)
#Resample rasters following standard parameters
rc <- terra::resample(rc, standard, method= "bilinear", threads= T)
#Rewrite the list layers with the result
results[[i]] <- rc
}
#Check the values
results[[4]]
#Rasterize the list to save it as a data frame
resampled<-rast(results)
df<-as.data.frame(resampled)
summary(df)
#Save the data frame in the project directory
data.table::fwrite(df, "~/Land use/DATASETS/resampled.csv")