subListExtract: Extract the same element from the sublists of a list
In turaganitesh/test-package: Test package: Base functions for Bioconductor

Description Usage Arguments Details Value Author(s) Examples

Given a list of lists, this function can be used to extract a named element from each sublist.

1	subListExtract(L, name, simplify = FALSE, keep.names = TRUE)

`L`	A list of named lists
`name`	The name of the element in the sublists that should be extracted. This should be a length one character vector.
`simplify`	When `TRUE`, the return value will be an atomic vector. If any extracted sublist value has length not equal to one and `simplify=TRUE`, an error will be raised. When `FALSE`, a list is returned containing the extracted elements.
`keep.names`	If `TRUE` (default), the names of `L` will be attached to the returned vector.

This function is implemented in C and is intended to be faster than calling lapply or sapply.

If simplify=FALSE, a list will be returned having the same length as L, but with each element containing the element named name from the corresponding inner list of L.

When simplify=TRUE, an atomic vector will be returned containing the extracted elements. If any of the inner list elements do not have length one or cannot be put inside an atomic vector, an error will be raised.

Seth Falcon

list_size = 500000
innerL = list(foo="foo", bar="bar")
L = rep(list(innerL), list_size)

system.time({j0 = sapply(L, function(x) x$foo)})
system.time({j1 = subListExtract(L, "foo", simplify=TRUE)})
stopifnot(all.equal(j0, j1))

LS = L[1:3]
names(LS) = LETTERS[1:3]
subListExtract(LS, "bar", simplify=TRUE)
subListExtract(LS, "bar", simplify=FALSE)
subListExtract(LS, "bar", simplify=TRUE, keep.names=FALSE)