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Fingerprint of objects or files

Source: R/stamps.R
content_hash.Rd

A short hash that changes whenever the content changes: of R objects (texts, rule lists, dictionaries), or of files (files = TRUE). Store it with a derived output (write_stamp()) or in a table column, to know which outputs must be recomputed after an input changed.

Usage

content_hash(x, files = FALSE, algo = "md5")

Arguments

x

An R object, or a character vector of file paths when files = TRUE.

files

Logical. Hash the content of the files named by x rather than x itself.

algo

Character. Hash algorithm passed to digest::digest().

Value

A string.

Details

For R objects, the hash is computed on the serialised object, so it also changes with attributes and types (1L and 1 differ). For text, hash the character vector itself; for files, the hash of each file is combined in the order given.

See also

Other versions: write_stamp()

Examples

content_hash(c("rule one", "rule two"))
#> [1] "7647bc2226a96cbd91182270813d67c4"
f <- tempfile()
writeLines("some text", f)
content_hash(f, files = TRUE)
#> [1] "da006516ab6e08eccf8298f114c3916e"