The variables that serve as unique identifiers. Defaults to NULL, at which point, all names which are not identified as variable groups are used as the identifiers.
var.stubs
The prefixes of the variable groups.
sep
The character that separates the "variable name" from the "times"
in the wide data.frame. Alternatively, can be set to
"var.stubs" (in quotes) if you do not have a value for sep.
keep.all
Logical. Should all the variables from the source
data.frame be kept (keep.all = TRUE) or should the resulting
data.table comprise only columns for
the id.vars, var.stubs, and "times" (keep.all = FALSE).
Other variables are recycled to appropriate length. For this to work,
both id.vars and var.stubs must be specified.
keyed
Logical. Should the Stacked function automatically set
the key for the resulting data.tables. If TRUE
(default) the key is set to the id.vars and the "time"
variables that are created by Stacked.
keep.rownames
Logical. Should rownames be kept when converting the input to a data.table? Defaults to FALSE.
...
Other arguments to be passed on when sep = "var.stubs" (specifically, atStart: A logical argument to indicate whether the stubs come at the start or at the end of the variable names).
Value
A list of data.tables with one data.table for
each "var.stub". The key is set to the
id.vars and .time_# vars.
Note
This is the function internally called by merged.stack.