objectdiff: Generate patch to turn one R object into another.

In robertzk/objectdiff: Objectdiff

Description

objectdiff is the central method used to generate "patches", closures that record a minimal amount of information to convert one object to another.

Objectdiff is an R package for measuring differences between arbitrary R objects using patches, a la Git. For example, if you have slightly modified a data.frame, and you would like to record the change, it would be more efficient to only record what is different, rather than a full copy of both data sets.

Usage

objectdiff(old_object, new_object, ...)

Arguments

old_object	ANY. The "before" object.
new_object	ANY. The "new" object. These are usually a data.frame or an environment.
...	future compatibility for extensions to this generic.

Value

a function that can transform old_object into new_object, but tries to keep memory footprint minimal. For example, if both are two data.frame's of 100,000s of rows and 1,000s of columns, but the only change made was the dropping of one column, the patching function will record only that information and not a full copy of both datasets.

Examples

iris2 <- iris[-1]
stopifnot(identical(objectdiff(iris, iris2)(iris), iris2))

beaver <- beaver1
patches <- list()
for (i in seq_len(10)) {
  old_beaver <- beaver
  beaver[seq(i*10, 9 + i*10), 1] <- i
  patches <- c(patches, objectdiff(old_beaver, beaver))
}
stopifnot(identical(
 beaver, Reduce(function(data, patch) patch(data), patches, beaver1)))
# The patches record the history of how we got from beaver1 to beaver
# We could go back to any previous step by applying only some of the
# patches.

robertzk/objectdiff documentation built on May 27, 2019, 10:35 a.m.