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R: Classes for user-defined Producers and Consumers

Function*

R Documentation

Classes for user-defined Producers and Consumers

Description

The FunctionProducer and FunctionConsumer classes provide an easy way to quickly create Producer and Consumer instances from user-provided functions.

Usage

FunctionProducer(FUN, RESET, ..., state=NULL)
FunctionConsumer(FUN, RESET, ..., state=NULL)

Arguments

`FUN`	User defined function to yield successive records in the stream. The `FunctionProducer` function must return an object of length 0 (e.g., `logical(0)`) when the stream is complete.
`RESET`	An optional function of one arugment (‘state’) to reset the stream to its original state. If missing, the stream cannot be reset.
`...`	Arguments passed to the `Producer`-class or `Consumer`-class constructors.
`state`	Any information, made available to `RESET`.

Constructors

Use FunctionProducer or FunctionConsumer to construct instances of this class.

Methods

See Producer and Consumer Methods.

Internal Class Fields and Methods

Internal fields of this class are are described with, e.g., getRefClass("FunctionProducer")$fields.

Internal methods of this class are described with getRefClass("FunctionProducer")$methods() and getRefClass("FunctionProducer")$help().

Author(s)

Nishant Gopalakrishnan ngopalak@fhcrc.org

Examples

## A ProducerFunction
producerFun <- function() 
    ## produce the mean of 10 random uniform numbers
    ## stop when the mean is greater than 0.8
{
    x <- mean(runif(10))
    if (x > .8) numeric(0) else x
}
randomSampleMeans <- FunctionProducer(producerFun)
result <- sapply(randomSampleMeans, c)
length(result)
head(result)

## A FunctionConsumer:
consumerFun <- function(y)
    ## transform input by -10 log10
{
    -10 * log10(y)
}

neg10log10 <- FunctionConsumer(consumerFun)

strm <- Stream(randomSampleMeans, neg10log10)
result <- sapply(strm, c)
length(result)
head(result)

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
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Platform: x86_64-pc-linux-gnu (64-bit)

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> library(Streamer)
> png(filename="/home/ddbj/snapshot/RGM3/R_BC/result/Streamer/FunctionProducerConsumer-classes.Rd_%03d_medium.png", width=480, height=480)
> ### Name: Function*
> ### Title: Classes for user-defined Producers and Consumers
> ### Aliases: Function* FunctionProducerConsumer-classes FunctionProducer
> ###   FunctionProducer-class FunctionConsumer FunctionConsumer-class
> ### Keywords: classes
> 
> ### ** Examples
> 
> ## A ProducerFunction
> producerFun <- function() 
+     ## produce the mean of 10 random uniform numbers
+     ## stop when the mean is greater than 0.8
+ {
+     x <- mean(runif(10))
+     if (x > .8) numeric(0) else x
+ }
> randomSampleMeans <- FunctionProducer(producerFun)
> result <- sapply(randomSampleMeans, c)
> length(result)
[1] 15072
> head(result)
[1] 0.5053140 0.5057702 0.5349482 0.4751352 0.5840785 0.5205261
> 
> ## A FunctionConsumer:
> consumerFun <- function(y)
+     ## transform input by -10 log10
+ {
+     -10 * log10(y)
+ }
> 
> neg10log10 <- FunctionConsumer(consumerFun)
> 
> strm <- Stream(randomSampleMeans, neg10log10)
> result <- sapply(strm, c)
> length(result)
[1] 4236
> head(result)
[1] 2.270060 3.112534 2.085345 1.800820 2.779226 2.826138
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>