ff (version 2.2-14)

CFUN: Collapsing functions for batch processing

Description

These are used in aggregating the chunks resulting from batch processing. They are usually called via do.call

Usage

ccbind(…)
crbind(…)
cfun(…, FUN, FUNARGS = list())
cquantile(…, probs = seq(0, 1, 0.25), na.rm = FALSE, names = TRUE, type = 7)
csummary(…, na.rm = "ignored")
cmedian(…, na.rm = FALSE)
clength(…, na.rm = FALSE)
csum(…, na.rm = FALSE)
cmean(…, na.rm = FALSE)

Arguments

…

…

FUN

a aggregating function

FUNARGS

further arguments to the aggregating function

na.rm

TRUE to remove NAs

probs

see quantile

names

see quantile

type

see quantile

Value

depends on the CFUN used

ff options

xx TODO: extend this for weighted means, weighted median etc., see http://tolstoy.newcastle.edu.au/R/help/02a/1073.html and http://tolstoy.newcastle.edu.au/R/help/02a/1060.html or google "Re: [R] Weighted median"

Details

CFUN	FUN	comment
ccbind	cbind	like cbind but respecting names
crbind	rbind	like rbind but respecting names
cfun		crbind the input chunks and then apply 'FUN' to each column
cquantile	quantile	crbind the input chunks and then apply 'quantile' to each column
csummary	summary	crbind the input chunks and then apply 'summary' to each column
cmedian	median	crbind the input chunks and then apply 'median' to each column
clength	length	crbind the input chunks and then determine the number of values in each column
csum	sum	crbind the input chunks and then determine the sum values in each column
cmean	mean	crbind the input chunks and then determine the (unweighted) mean in each column

In order to use CFUNs on the result of lapply or ffapply use do.call.

See Also

ffapply, do.call, na.count

Examples

# NOT RUN {
   X <- lapply(split(rnorm(1000), 1:10), summary)
   do.call("crbind", X)
   do.call("csummary", X)
   do.call("cmean", X)
   do.call("cfun", c(X, list(FUN=mean, FUNARGS=list(na.rm=TRUE))))
   rm(X)
# }