| bitwhich {bit} | R Documentation |
A bitwhich object like the result of which and as.which does represent integer subscript positions,
but bitwhich objects represent some subscripts rather with negative integers, if this needs less space.
The extreme cases of selecting all/none subscripts are represented by TRUE/FALSE.
This needs less RAM compared to logical (and often less than as.which).
Logical operations are fast if the selection is asymetric (only few or almost all selected).
bitwhich(maxindex, poslength = NULL, x = NULL)
maxindex |
the length of the vector (sum of all TRUEs and FALSEs) |
poslength |
Only use if x is not NULL: the sum of all TRUEs |
x |
Default NULL or FALSE or unique negative integers or unique positive integers or TRUE |
class 'bitwhich' represents a boolean selection in one of the following ways
FALSE to select nothing
TRUE to select everything
unique positive integers to select those
unique negative integers to exclude those
An object of class 'bitwhich' carrying two attributes
maxindex |
see above |
poslength |
see above |
Jens Oehlschlägel
bitwhich(12, x=c(1,3), poslength=2) bitwhich(12, x=-c(1,3), poslength=10)