Common higher-order functions in functional programming languages

Description

Reduce uses a binary function to successively combine the elements of a given list-like or vector-like object and a possibly given initial value. Filter extracts the elements of a list-like or vector-like object for which a predicate (logical) function gives true. Find and Position give the first or last such element and its position in the object, respectively. Map applies a function to the corresponding elements of given list-like or vector-like objects.

NOTE: This man page is for the Reduce, Filter, Find, Map and Position S4 generic functions defined in the BiocGenerics package. See ?base::Reduce for the default methods (defined in the base package). Bioconductor packages can define specific methods for objects (typically list-like or vector-like) not supported by the default methods.

Usage

Reduce(f, x, init, right=FALSE, accumulate=FALSE, simplify=TRUE)
Filter(f, x)
Find(f, x, right=FALSE, nomatch=NULL)
Map(f, ...)
Position(f, x, right=FALSE, nomatch=NA_integer_)

Arguments

Value

See ?base::Reduce for the value returned by the default methods.

Specific methods defined in Bioconductor packages should behave as consistently as possible with the default methods.

See Also

• base::Reduce for the default Reduce, Filter, Find, Map and Position methods.

• showMethods for displaying a summary of the methods defined for a given generic function.

• selectMethod for getting the definition of a specific method.

• Reduce,List-method in the S4Vectors package for an example of a specific Reduce method (defined for List objects).

• BiocGenerics for a summary of all the generics defined in the BiocGenerics package.

Examples

Reduce  # note the dispatch on the 'x' arg only
showMethods("Reduce")
selectMethod("Reduce", "ANY")  # the default method

Filter  # note the dispatch on the 'x' arg only
showMethods("Filter")
selectMethod("Filter", "ANY")  # the default method

Find  # note the dispatch on the 'x' arg only
showMethods("Find")
selectMethod("Find", "ANY")  # the default method

Map  # note the dispatch on the '...' arg only
showMethods("Map")
selectMethod("Map", "ANY")  # the default method

Position  # note the dispatch on the 'x' arg only
showMethods("Position")
selectMethod("Position", "ANY")  # the default method