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Returns the first item of a vector or list, or the first row of a data.frame or data.table.
first(x, ...)A vector, list, data.frame or data.table. Otherwise the S3 method
of xts::first is deployed.
Not applicable for data.table::first. Any arguments here
are passed through to xts::first.
If no other arguments are supplied it depends on the type of x. The first item
of a vector or list. The first row of a data.frame or data.table.
Otherwise, whatever xts::first returns (if package xts has been loaded,
otherwise a helpful error).
If any argument is supplied in addition to x (such as n or
keep in xts::first), regardless of x's type, then
xts::first is called if xts has been loaded, otherwise a helpful error.
# NOT RUN {
first(1:5) # [1] 1
x = data.table(x=1:5, y=6:10)
first(x) # same as x[1]
# }
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