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Hashing

Source: R/hash.R
hash.Rd

  • hash() hashes an arbitrary R object.

  • hash_file() hashes the data contained in a file.

The generated hash is guaranteed to be reproducible across platforms that have the same endianness and are using the same R version.

Usage

hash(x)

hash_file(path)

Arguments

x

An object.

path

A character vector of paths to the files to be hashed.

Value

  • For hash(), a single character string containing the hash.

  • For hash_file(), a character vector containing one hash per file.

Details

These hashers use the XXH128 hash algorithm of the xxHash library, which generates a 128-bit hash. Both are implemented as streaming hashes, which generate the hash with minimal extra memory usage.

For hash(), objects are converted to binary using R's native serialization tools. Serialization version 3 is used. See serialize() for more information about the serialization version.

Examples

hash(c(1, 2, 3))
#> [1] "702f7dd6e81ea41d26ea3b248627ece4"
hash(mtcars)
#> [1] "d0487363db4e6cc64fdb740cb6617fc0"

authors <- file.path(R.home("doc"), "AUTHORS")
copying <- file.path(R.home("doc"), "COPYING")
hashes <- hash_file(c(authors, copying))
hashes
#> [1] "fc4d57b62fa48aa0e3fb847cdce2cf88"
#> [2] "cdb3a24318136e74f38209c219ca104b"

# If you need a single hash for multiple files,
# hash the result of `hash_file()`
hash(hashes)
#> [1] "a061b5938a6bd7c4beb6e2dc25f470a3"