Digest an arbitrary R object

Fingerprints any R object by hashing its serialization, so a list, a data frame, a function or a fitted model all get a stable digest. The counterpart of digest::digest(), computed with this package's own hashes.

Usage

digest_object(x, algo = c("sha256", "sha512", "blake2b", "crc32"), key = NULL)

Arguments

x

Any R object.

algo

"sha256" (default), "sha512", "blake2b" or "crc32".

key

Optional key, for "blake2b" only: gives a keyed fingerprint that only a key holder can reproduce.

Value

A length-1 character vector (or numeric for "crc32") .

Details

Serialization is pinned to version 2 with XDR byte order, so the digest is the same on a big-endian machine as on a little-endian one. Two objects that are identical() produce the same digest; two that merely print the same need not, because attributes are part of the serialization.

See also

core_sha256() for hashing text or bytes directly, bricklayer_json_serialize() for a readable lossless form.

Examples

digest_object(list(a = 1L, b = "x"))
#> [1] "bf5d21a8b26f6cec8503a46f69e854bf98fea03b62dfaf90cb780feac7165b27"

# Stable across calls, and sensitive to any change.
identical(digest_object(1:10), digest_object(1:10))
#> [1] TRUE
digest_object(1:10) == digest_object(1:11)
#> [1] FALSE

# Attributes are part of the object, so they are part of the digest.
digest_object(matrix(1:6, nrow = 2)) == digest_object(1:6)
#> [1] FALSE

# Any of the hashes, and a keyed fingerprint.
digest_object(mtcars, algo = "sha512")
#> [1] "c53613500c91362b1d1ff5b142277240a9f80aa35ad4e6e8f1642c8c1023d79d2e249b54ffe9c6f1a176fb337eca8cd57c7e057d473f0f3137e319c890477655"
digest_object(mtcars, algo = "crc32")
#> [1] 358362979
digest_object(mtcars, algo = "blake2b", key = "secret")
#> [1] "fa9c0c955ca0d50abcb2bc2a984cbd143035beeaf7366c689755873d8aa84d8d"

# A data frame's digest pins the data, so it can go in a manifest.
digest_object(data.frame(x = 1:3))
#> [1] "24b0995a368ea8d1178b7f6e44c6d8956db4aadfc91d3e6f6911868b38c06d21"