Hybrid Index, C-coded utilities
These C-coded utilitites speed up index preprocessing considerably.
intrle(x)
intisasc(x, na.method = c("none", "break", "skip")[2])
intisdesc(x, na.method = c("none", "break", "skip")[1])x |
an integer vector |
na.method |
one of "none","break","skip", see details. The strange defaults stem from the initial usage. |
intrle is by factor 50 faster and needs less RAM (2x its input
vector) compared to rle which needs 9x the RAM of its input
vector. This is achieved because we allow the C-code of intrle to
break when it turns out, that rle-packing will not achieve a compression
factor of 3 or better. intisasc is a faster version of
is.unsorted: it checks whether x is sorted.intisdesc checks for being sorted descending and
by default default assumes that the input x contains no NAs.
na.method="none" treats NAs (the smallest integer) like every other integer and hence returns either TRUE or FALSE
na.method="break" checks for NAs and returns either NA as soon as NA is encountered.
na.method="skip" checks for NAs and skips over them, hence decides the return value only on the basis of non-NA values.
intrle returns an object of class rle or NULL,
if rle-compression is not efficient (compression factor <3 or length(x)<3).
intisasc returns one of FALSE, NA, TRUE intisdesc returns one of FALSE, TRUE (if the input contains
NAs, the output is undefined)
intisasc: check whether integer vector is ascending
intisdesc: check whether integer vector is descending
Jens Oehlschlägel
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")
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