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45 lines
1.3 KiB
R
45 lines
1.3 KiB
R
# Cache the value of an expression on the file system.
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#
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# The expression will be evaluated if there is no matching cache file found.
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# The cache files will be located in a directory "cache" located in the current
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# working directory.
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#
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# @param name Human readable part of the cache file name.
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# @param objects A vector of objects that this expression depends on. The hash
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# of those objects will be used for identifying the cache file.
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cached <- function(name, objects, expr) {
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if (!dir.exists("cache")) {
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dir.create("cache")
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}
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id <- rlang::hash(objects)
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cache_file <- sprintf("cache/%s_%s.rda", name, id)
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if (file.exists(cache_file)) {
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# If the cache file exists, we restore the data from it.
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load(cache_file)
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} else {
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# If the cache file doesn't exist, we have to do the computation.
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data <- expr
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# The results are cached for the next run.
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save(data, file = cache_file, compress = "xz")
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}
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data
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}
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#' Format and round a numeric value.
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#'
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#' @param number The number to use.
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#' @param digits Number of decimal places.
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#'
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#' @return A character value.
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#' @noRd
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num <- function(number, digits) {
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format(round(number, digits = digits), nsmall = digits)
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}
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# This is needed to make data.table's symbols available within the package.
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#' @import data.table
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NULL
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