heads function

Apply head() across each element in a list of vectors

heads(x, n = 6, ...)

Arguments

• x: list of atomic vectors, assumed to be the same atomic type.
• n: integer maximum number of items to include from each element in the list x. When n contains multiple values, they are recycled to length(x) and applied to each list element in order.
• ...: additional arguments are passed to utils::head().

Returns

list with at most n elements per vector.

Details

Note that this function currently only operates on a list of vectors. This function is notably faster than lapply(x, head, n) because it operates on the entire vector in one step.

Also the input n can be a vector so that each element in the list has a specific number of items returned.

Examples

l <- list(a=1:10, b=2:5, c=NULL, d=1:100);
heads(l, 1);

heads(l, 2);

heads(l, n=c(2, 1, 3, 5))

See Also

Other jam list functions: cPaste(), jam_rapply(), list2df(), mergeAllXY(), mixedSorts(), rbindList(), relist_named(), rlengths(), sclass(), sdim(), uniques(), unnestList()