saving and naming files in R automatically based on input filename - r

Question

I have generated several Utilisation Distributions (UD) with AdehabitatHR and stored them as Geotiffs. I am now using the same UDs with the Lattice package to generate some maps and saving them to a high-res tiff image with LZW compression. Problem is that I have literally hundreds of maps to make, save and name. Is there a way automatically do this once i have loaded all the necessary files from a directory? Each one of my UDs has the following structure of the filename "UD_resolution_species_area_year_season. tif" and in the final name I give to my map I would like to keep the same structure (or entire filename) but add the prefix "blablabla_" e.g. "blablabla_UD_resolution_species_area_year_season.tiff". The image also include a main name, a capital letter, which should also change.
At the moment I am using the following:
rlist = list.files(getwd(), pattern = "tif$", full.names = FALSE)
for (i in rlist) {
assign(unlist(strsplit(i, "[.]"))[1], raster(i))
}
shplist = list.files(getwd(), pattern = "shp$", full.names = FALSE)
for (i in shplist) {
assign(unlist(strsplit(i, "[.]"))[1], readOGR(i))
}
UD <- 'UD_resolution_species_area_year_season'
ext <- extent(UD) + 0.3 # set the extent for the plot
aa <-
quantile(UD,
probs = c(0.25, 0.75),
type = 8,
names = TRUE)
my.at <- c(aa[1], aa[2])
my.at <- round(my.at, 3)
maxval <- maxValue(UD)
tiff(
"C:/myworkingdirectory/maps/blablabla_UD_resolution_species_area_year_season.tiff",
res = 600,
compression = "lzw",
width = 15,
height = 15,
units = "cm"
)
levelplot(
UD,
xlab = "",
ylab = "",
xlim = c(ext[1], ext[2]),
ylim = c(ext[3], ext[4]),
margin = FALSE,
contour = FALSE,
col.regions = viridis(1000),
colorkey = list(at = seq(0, maxval)),
main = "A",
maxpixels = 2e5
) + latticeExtra::layer(sp.polygons(Land, fill = "grey50", col = NA)) + contourplot(
`UD`,
at = my.at[1],
labels = FALSE,
margin = FALSE,
lty = 2,
col = "orange",
pretty = TRUE
) + contourplot(
UD,
at = my.at[2],
labels = FALSE,
margin = FALSE,
lty = 2,
col = "red",
pretty = TRUE,
)
dev.off()

Answer 1

It is a common beginners mistake to use assign. Do not use it, it creates the type of trouble you are now facing. In stead, you can make lists and/or use a loop.
Also what you are asking is basic R stuff, but you are complicating the question with adding lots of irrelevant detail about setting the extent, and levelplot. It is better to learn about doing these basic things by removing the clutter and focus on a simple case first. That is also how you should write questions for this forum.
In essence you have a bunch of files you want to process. Below I show how you can loop over a vector of the names and then loop and do what you need to do in that loop.
library(raster)
rastfiles <- list.files(pattern = "tif$", full.names=TRUE)
outputfiles <- file.path("output/path", paste0("prefix_", basename(rastfiles)))
for (i in 1:length(rastfiles))
r <- raster(rastfiles[i])
png(outputfiles[i])
plot(r)
dev.off()
}
You can also first read all the files into a list
rastfiles <- list.files(pattern = "tif$", full.names=TRUE)
rlist <- lapply(rastfiles, raster)
names(rlist) <- gsub(".tif$", "", basename(rastfiles))
rastfiles <- list.files(pattern = "shp$", full.names=TRUE)
slist <- lapply(shpfiles, readOGR)
names(slist) <- gsub(".shp$", "", basename(shpfiles))
And perhaps create a vector of output filenames
outputtif <- file.path("output/dir", basename(rastfiles))
And then loop over the items in the list, or the output filenames