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
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/rle.R
\name{intrle}
\alias{intrle}
\alias{intisasc}
\alias{intisdesc}
\title{Hybrid Index, C-coded utilities}
\usage{
intrle(x)
intisasc(x, na.method = c("none", "break", "skip")[2])
intisdesc(x, na.method = c("none", "break", "skip")[1])
}
\arguments{
\item{x}{an integer vector}
\item{na.method}{one of "none", "break", "skip", see details. The strange defaults stem
from the initial usage.}
}
\value{
\itemize{
\item \code{intrle} returns an object of class \code{\link[=rle]{rle()}} or NULL, if rle-compression is not
efficient (compression factor <3 or \code{length(x) < 3}).
\item \code{intisasc} returns one of \verb{FALSE, NA, TRUE}
\item \code{intisdesc} returns one of \verb{FALSE, TRUE} (if the input contains NAs, the output is
undefined)
}
}
\description{
These C-coded utilitites speed up index preprocessing considerably.
}
\details{
\code{intrle} is by factor 50 faster and needs less RAM (2x its input
vector) compared to \code{\link[=rle]{rle()}} which needs 9x the RAM of its input
vector. This is achieved because we allow the C-code of \code{intrle} to
break when it turns out, that rle-packing will not achieve a compression
factor of 3 or better.
\code{intisasc} is a faster version of \code{\link[=is.unsorted]{is.unsorted()}}: it checks whether \code{x} is sorted.
\code{intisdesc} checks for being sorted descending and by default default assumes that the
input \code{x} contains no NAs.
\code{na.method="none"} treats \code{NAs} (the smallest integer) like every other integer and
hence returns either \code{TRUE} or \code{FALSE} \code{na.method="break"} checks for \code{NAs} and
returns either \code{NA} as soon as \code{NA} is encountered. \code{na.method="skip"} checks for
\code{NAs} and skips over them, hence decides the return value only on the basis of
non-NA values.
}
\section{Functions}{
\itemize{
\item \code{intisasc()}: check whether integer vector is ascending
\item \code{intisdesc()}: check whether integer vector is descending
}}
\examples{
intrle(sample(1:10))
intrle(diff(1:10))
intisasc(1:10)
intisasc(10:1)
intisasc(c(NA, 1:10))
intisdesc(1:10)
intisdesc(c(10:1, NA))
intisdesc(c(10:6, NA, 5:1))
intisdesc(c(10:6, NA, 5:1), na.method="skip")
intisdesc(c(10:6, NA, 5:1), na.method="break")
}
\seealso{
\code{\link[ff:hi]{ff::hi()}}, \code{\link[=rle]{rle()}}, \code{\link[=is.unsorted]{is.unsorted()}},
\code{\link[ff:is.sorted]{ff::is.sorted.default()}}
}
\author{
Jens Oehlschlägel
}
\keyword{IO}
\keyword{data}
|
