| read_vc {git2rdata} | R Documentation |
Read a Git2rdata Object from Disk
Description
read_vc() handles git2rdata objects stored by write_vc(). It reads and
verifies the metadata file (.yml). Then it reads and verifies the raw data.
The last step is back-transforming any transformation done by meta() to
return the data.frame as stored by write_vc().
read_vc() is an S3 generic on root which currently handles "character"
(a path) and "git-repository" (from git2r). S3 methods for other version
control system could be added.
Usage
read_vc(file, root = ".")
Arguments
file |
the name of the git2rdata object. Git2rdata objects cannot
have dots in their name. The name may include a relative path. |
root |
The root of a project. Can be a file path or a |
Value
The data.frame with the file names and hashes as attributes.
See Also
Other storage:
list_data(),
prune_meta(),
relabel(),
rename_variable(),
rm_data(),
verify_vc(),
write_vc()
Examples
## on file system
# create a directory
root <- tempfile("git2rdata-")
dir.create(root)
# write a dataframe to the directory
write_vc(iris[1:6, ], file = "iris", root = root, sorting = "Sepal.Length")
# check that a data file (.tsv) and a metadata file (.yml) exist.
list.files(root, recursive = TRUE)
# read the git2rdata object from the directory
read_vc("iris", root)
# store a new version with different observations but the same metadata
write_vc(iris[1:5, ], "iris", root)
list.files(root, recursive = TRUE)
# Removing a column requires version requires new metadata.
# Add strict = FALSE to override the existing metadata.
write_vc(
iris[1:6, -2], "iris", root, sorting = "Sepal.Length", strict = FALSE
)
list.files(root, recursive = TRUE)
# storing the orignal version again requires another update of the metadata
write_vc(iris[1:6, ], "iris", root, sorting = "Sepal.Width", strict = FALSE)
list.files(root, recursive = TRUE)
# optimize = FALSE stores the data more verbose. This requires larger files.
write_vc(
iris[1:6, ], "iris2", root, sorting = "Sepal.Width", optimize = FALSE
)
list.files(root, recursive = TRUE)
## on git repo using a git2r::git-repository
# initialise a git repo using the git2r package
repo_path <- tempfile("git2rdata-repo-")
dir.create(repo_path)
repo <- git2r::init(repo_path)
git2r::config(repo, user.name = "Alice", user.email = "alice@example.org")
# store a dataframe in git repo.
write_vc(iris[1:6, ], file = "iris", root = repo, sorting = "Sepal.Length")
# This git2rdata object is not staged by default.
status(repo)
# read a dataframe from a git repo
read_vc("iris", repo)
# store a new version in the git repo and stage it in one go
write_vc(iris[1:5, ], "iris", repo, stage = TRUE)
status(repo)
# store a verbose version in a different gir2data object
write_vc(
iris[1:6, ], "iris2", repo, sorting = "Sepal.Width", optimize = FALSE
)
status(repo)