Return DataObjects or DataObject identifiers that match search terms.
Usage
selectMember(x, ...)
# S4 method for DataPackage
selectMember(x, name, value, as = "character")Arguments
- x
A DataPackage instance
- ...
(Not yet used)
- name
The name of the DataObject slot to inspect, for example "sysmeta@formatId".
- value
A character or logical value to match. If specified as a character value, PERL style regular expressions can be used (see ?grepl).
- as
A character value to specify the return type, either "DataObject" or "character" (the default)
Value
A list of matching DataObjects or DataObject identifiers. The default is to return a list of DataObject identifiers.
Details
The "selectMember" method inspects the DataObject slot "name" for a match with "value"
for each DataObject in a DataPackage. Matching DataObjects are returned as a list containing either package member
identifiers (character) or the DataObjects themselves, depending on the value of the as parameter.
Examples
#' library(datapack)
dp <- new("DataPackage")
# Add the script to the DataPackage
progFile <- system.file("./extdata/pkg-example/logit-regression-example.R", package="datapack")
# An 'id' parameter is not specified, so one will be generated automatically.
progObj <- new("DataObject", format="application/R", filename=progFile)
dp <- addMember(dp, progObj)
# Add a script input to the DataPackage
inFile <- system.file("./extdata/pkg-example/binary.csv", package="datapack")
inObj <- new("DataObject", format="text/csv", filename=inFile)
dp <- addMember(dp, inObj)
# Add a script output to the DataPackage
outFile <- system.file("./extdata/pkg-example/gre-predicted.png", package="datapack")
outObj <- new("DataObject", format="image/png", file=outFile)
dp <- addMember(dp, outObj)
# Now determine the package member identifier for the R script
progIds <- selectMember(dp, name="sysmeta@formatId", value="application/R", as="character")
inputId <- selectMember(dp, name="sysmeta@fileName", value="binary.csv")