modifyList {utils}

Recursively Modify Elements of a List

Description

Modifies a possibly nested list recursively by changing a subset of elements at each level to match a second list.

Usage

modifyList(x, val, keep.null = FALSE)

Arguments

x

A named list, possibly empty.

val

A named list with components to replace corresponding components in x or add new components.

keep.null

If TRUE, NULL elements in val become NULL elements in x. Otherwise, the corresponding element, if present, is deleted from x.

Value

A modified version of x, with the modifications determined as follows (here, list elements are identified by their names). Elements in val which are missing from x are added to x. For elements that are common to both but are not both lists themselves, the component in x is replaced (or possibly deleted, depending on the value of keep.null) by the one in val. For common elements that are in both lists, x[[name]] is replaced by modifyList(x[[name]], val[[name]]).

Author(s)

Deepayan Sarkar [e-mail]

Examples

foo <- list(a = 1, b = list(c = "a", d = FALSE))
bar <- modifyList(foo, list(e = 2, b = list(d = TRUE)))
str(foo)
str(bar)