bitwhich {bit} | R Documentation |
A bitwhich object represents a boolean filter like a bit
object (NAs are not allowed)
but uses a sparse representation suitable for very skewed (asymmetric) selections.
Three extreme cases are represented with logical values, no length via logical(),
all TRUE with TRUE and all FALSE with FALSE. All other selections are represented with
positive or negative integers, whatever is shorter.
This needs less RAM compared to logical
(and often less than bit
or which
).
Logical operations are fast if the selection is asymetric (only few or almost all selected).
bitwhich( maxindex = 0L, x = NULL, xempty = FALSE, poslength = NULL, is.unsorted = TRUE, has.dup = TRUE )
maxindex |
length of the vector |
x |
Information about which positions are FALSE or TRUE: either |
xempty |
what to assume about parameter |
poslength |
tuning: |
is.unsorted |
tuning: FALSE implies that |
has.dup |
tuning: FALSE implies that |
an object of class 'bitwhich' carrying two attributes
see above
see above
bitwhich_representation
, as.bitwhich
, bit
bitwhich() bitwhich(12) bitwhich(12, x=TRUE) bitwhich(12, x=3) bitwhich(12, x=-3) bitwhich(12, x=integer()) bitwhich(12, x=integer(), xempty=TRUE)