Versions

Give data sets versions, and identify them by version.

Giving data sets a version

Multiple editions of a data set can be described by using the same name, but setting the version parameter to differentiate them.

For instance, say that Ronald Fisher released a second version of the "Iris" data set, with more flowers. We could specify this as:

[[iris]]
version = "1"
...

[[iris]]
version = "2"
...

Matching by version

Version matching is done via the Identifier parameter "version". As shorthand, instead of providing the "version" parameter manually, the version can be tacked onto the end of an identifier with @, e.g. iris@1 or iris@2.

The version matching re-uses machinery from Pkg, and so all Pkg-style version specifications are supported. In addition to this, one can simply request the "latest" version.

The following are all valid identifiers, using the @-shorthand:

iris@1
iris@~1
iris@>=2
iris@latest

When multiple data sets match the version specification, the one with the highest matching version is used.