iterators (version 1.0.14)

iter: Iterator Factory Functions

Description

iter is a generic function used to create iterator objects.

Usage

iter(obj, …)

# S3 method for default iter(obj, checkFunc=function(...) TRUE, recycle=FALSE, …) # S3 method for iter iter(obj, …) # S3 method for matrix iter(obj, by=c('column', 'cell', 'row'), chunksize=1L, checkFunc=function(...) TRUE, recycle=FALSE, …) # S3 method for data.frame iter(obj, by=c('column', 'row'), checkFunc=function(...) TRUE, recycle=FALSE, …) # S3 method for function iter(obj, checkFunc=function(...) TRUE, recycle=FALSE, …)

Arguments

obj

an object from which to generate an iterator.

by

how to iterate.

chunksize

the number of elements of by to return with each call to nextElem.

checkFunc

a function which, when passed an iterator value, return TRUE or FALSE. If FALSE, the value is skipped in the iteration.

recycle

a boolean describing whether the iterator should reset after running through all it's values.

additional arguments affecting the iterator.

Value

The iterator.

Examples

Run this code
# NOT RUN {
  # a vector iterator
  i1 <- iter(1:3)
  nextElem(i1)
  nextElem(i1)
  nextElem(i1)

  # a vector iterator with a checkFunc
  i1 <- iter(1:3, checkFunc=function(i) i %% 2 == 0)
  nextElem(i1)

  # a data frame iterator by column
  i2 <- iter(data.frame(x=1:3, y=10, z=c('a', 'b', 'c')))
  nextElem(i2)
  nextElem(i2)
  nextElem(i2)

  # a data frame iterator by row
  i3 <- iter(data.frame(x=1:3, y=10), by='row')
  nextElem(i3)
  nextElem(i3)
  nextElem(i3)

  # a function iterator
  i4 <- iter(function() rnorm(1))
  nextElem(i4)
  nextElem(i4)
  nextElem(i4)
# }

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