Diff, Patch and Merge for Data.frames

Diff, patch and merge for data frames. Document changes in data sets and use them to apply patches. Changes to data can be made visible by using render_diff(). The 'V8' package is used to wrap the 'daff.js' 'JavaScript' library which is included in the package.

Daff: diff, patch and merge for data.frames

daff is an R package that can find difference in values between data.frames, store this difference, render it and apply this difference to patch a data.frame. It can also merge two versions of a data.frame having a common parent. It wraps the daff.js library using the V8 package.

The diff format is described in https://paulfitz.github.io/daff-doc/spec.html.

Functions:

• diff: diff_data
• patch: patch_data
• write/read diff: read_diff and write_diff
• render to html: render_diff
• merge two tables based on a same version: merge_data

Installation

You can install the development version of daff from GitHub with:

# install.packages("devtools")
devtools::install_github("edwindj/daff")

Usage

diff_data

Calculate the difference between a reference and a changed data.frame

library(daff)
y <- iris[1:3,]
x <- y

x <- head(x,2) # remove a row
x[1,1] <- 10 # change a value
x$hello <- "world"  # add a column
x$Species <- NULL # remove a column

patch <- diff_data(y, x)

# write a patch to disk
write_diff(patch, "patch.csv")

render_diff(patch) will generate the following HTML page:

patch_data

Patch a data.frame using a diff generated with diff_data.

# read a diff from disk
patch <- read_diff("patch.csv")

# apply patch
y_patched <- patch_data(y, patch)

merge_data

Merge two data.frames that have diverged from a common parent data.frame.

parent <- a <- b <- iris[1:3,]
a[1,1] <- 10
b[2,1] <- 11
# succesful merge
merge_data(parent, a, b)

parent <- a <- b <- iris[1:3,]
a[1,1] <- 10
b[1,1] <- 11
# conflicting merge (both a and b change same cell)
merged <- merge_data(parent, a, b)
merged #note the conflict

#find out which rows contain a conflict
which_conflicts(merged)