Description Usage Arguments Details Value Author(s) See Also Examples
Various functions and methods for looping on List objects, functional programming on List objects, and evaluation of an expression in a List object.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44  ## Looping on List objects:
## 
## S4 method for signature 'List'
lapply(X, FUN, ...)
## S4 method for signature 'List'
sapply(X, FUN, ..., simplify=TRUE, USE.NAMES=TRUE)
endoapply(X, FUN, ...)
revElements(x, i)
mendoapply(FUN, ..., MoreArgs=NULL)
pc(...)
## Functional programming methods for List objects:
## 
## S4 method for signature 'List'
Reduce(f, x, init, right=FALSE, accumulate=FALSE)
## S4 method for signature 'List'
Filter(f, x)
## S4 method for signature 'List'
Find(f, x, right=FALSE, nomatch=NULL)
## S4 method for signature 'List'
Map(f, ...)
## S4 method for signature 'List'
Position(f, x, right=FALSE, nomatch=NA_integer_)
## Evaluation of an expression in a List object:
## 
## S4 method for signature 'List'
within(data, expr, ...)
## Constructing list matrices:
## 
## S4 method for signature 'List'
rbind(..., deparse.level=1L)
## S4 method for signature 'List'
cbind(..., deparse.level=1L)

X, x 
A list, data.frame or List object. 
FUN 
The function to be applied to each element of 
... 
For For 
simplify, USE.NAMES 
See 
MoreArgs 
A list of other arguments to 
i 
Index specifying the elements to replace. Can be anything supported
by 
f, init, right, accumulate, nomatch 
See 
data 
A List object. 
expr 
Expression to evaluate. 
deparse.level 
See 
Like the standard lapply
function defined in the
base package, the lapply
method for List objects
returns a list of the same length as X
, with each element being
the result of applying FUN
to the corresponding element of X
.
Like the standard sapply
function defined in the
base package, the sapply
method for List objects
is a userfriendly version of lapply
by default returning a vector
or matrix if appropriate.
endoapply
and mendoapply
perform the endomorphic equivalents
of lapply
and mapply
by returning
objects of the same class as the inputs rather than an ordinary list.
revElements(x, i)
reverses the list elements in x
specified
by i
. It's equivalent to, but faster than, doing
x[i] < endoapply(x[i], rev)
.
pc(...)
combine listlike objects by concatenating them in an
elementwise fashion. It's similar to, but faster than,
mapply(c, ..., SIMPLIFY=FALSE)
. With the following differences:
pc()
ignores the supplied objects that are NULL.
pc()
does not recycle its arguments. All the supplied
objects must have the same length.
If one of the supplied objects is a List object, then
pc()
returns a List object.
pc()
always returns a homogenous list or List object,
that is, an object where all the list elements have the same type.
The R base package defines some higherorder functions that are commonly
found in Functional Programming Languages.
See ?base::Reduce
for the details, and, in particular,
for a description of their arguments.
The S4Vectors package provides methods for List objects, so,
in addition to be an ordinary vector or list, the x
argument can
also be a List object.
within
evaluates expr
within as.env(data)
via
eval(data)
. Similar to with
, except assignments made
during evaluation are taken as assignments into data
, i.e.,
new symbols have their value appended to data
, and assigning
new values to existing symbols results in replacement.
There are methods for cbind
and rbind
that will bind
multiple lists together into a basic list matrix. The usual
geometric constraints apply. In the future, this might return a List
(+ dimensions), but for now the return value is an ordinary list.
endoapply
returns an object of the same class as X
,
each element of which is the result of applying FUN
to the
corresponding element of X
.
mendoapply
returns an object of the same class as the first
object specified in ...
, each element of which is the result
of applying FUN
to the corresponding elements of ...
.
pc
returns a list or List object of the same length as the
input objects.
See ?base::Reduce
for the value returned by the
functional programming methods.
See ?base::within
for the value returned by
within
.
cbind
and rbind
return a list matrix.
P. Aboyoun and H. Pagès
The List class.
base::lapply
and base::mapply
for the default lapply
and mapply
methods.
base::Reduce
for the default functional
programming methods.
base::within
for the default within
method.
base::cbind
and
base::rbind
for the default matrix binding
methods.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30  a < data.frame(x = 1:10, y = rnorm(10))
b < data.frame(x = 1:10, y = rnorm(10))
endoapply(a, function(x) (x  mean(x))/sd(x))
mendoapply(function(e1, e2) (e1  mean(e1)) * (e2  mean(e2)), a, b)
x < list(a=11:13, b=26:21, c=letters)
y < list((5:1), c("foo", "bar"), 0.25)
pc(x, y)
library(IRanges)
x < IntegerList(a=11:13, b=26:21, c=31:36, d=4:2)
y < NumericList((5:1), 1:2, numeric(0), 0.25)
pc(x, y)
Reduce("+", x)
Filter(is.unsorted, x)
pos1 < Position(is.unsorted, x)
stopifnot(identical(Find(is.unsorted, x), x[[pos1]]))
pos2 < Position(is.unsorted, x, right=TRUE)
stopifnot(identical(Find(is.unsorted, x, right=TRUE), x[[pos2]]))
y < x * 1000L
Map("c", x, y)
rbind(x, y)
cbind(x, y)

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