last {data.table} | R Documentation |
Returns the first/last item of a vector or list, or the first/last row of a data.frame
or data.table. The main difference to head/tail is that the default for n
is 1
rather than 6.
first(x, n=1L, ...)
last(x, n=1L, ...)
x |
A vector, list, data.frame or data.table. Otherwise the S3 method
of |
n |
A numeric vector length 1. How many items to select. |
... |
Not applicable for |
If no other arguments are supplied it depends on the type of x
. The first/last item
of a vector or list. The first/last row of a data.frame
or data.table
.
For other types, or if any argument is supplied in addition to x
(such as n
, or
keep
in xts
) regardless of x
's type, then xts::first
/
xts::last
is called if xts
has been loaded, otherwise utils::head
/utils::tail
.
first(1:5) # [1] 1
x = data.table(x=1:5, y=6:10)
first(x) # same as head(x, 1)
last(1:5) # [1] 5
x = data.table(x=1:5, y=6:10)
last(x) # same as tail(x, 1)