Extract Positions of Unique Elements
unipos returns the positions of those elements returned by unique.
unipos(x, incomparables = FALSE, order = c("original","values","any"), ...)
## S3 method for class 'integer64'
unipos(x, incomparables = FALSE, order = c("original","values","any")
, nunique = NULL, method = NULL, ...)x |
a vector or a data frame or an array or |
incomparables |
ignored |
order |
The order in which positions of unique values will be returned, see details |
nunique |
NULL or the number of unique values (including NA). Providing |
method |
NULL for automatic method selection or a suitable low-level method, see details |
... |
ignored |
This function automatically chooses from several low-level functions considering the size of x and the availability of a cache.
Suitable methods are hashmapupo (simultaneously creating and using a hashmap)
, hashupo (first creating a hashmap then using it)
, sortorderupo (fast ordering)
and orderupo (memory saving ordering).
The default order="original" collects unique values in the order of the first appearance in x like in unique, this costs extra processing.
order="values" collects unique values in sorted order like in table, this costs extra processing with the hash methods but comes for free.
order="any" collects unique values in undefined order, possibly faster. For hash methods this will be a quasi random order, for sort methods this will be sorted order.
an integer vector of positions
Jens Oehlschlägel <Jens.Oehlschlaegel@truecluster.com>
unique.integer64 for unique values and match.integer64 for general matching.
x <- as.integer64(sample(c(rep(NA, 9), 1:9), 32, TRUE)) unipos(x) unipos(x, order="values") stopifnot(identical(unipos(x), (1:length(x))[!duplicated(x)])) stopifnot(identical(unipos(x), match.integer64(unique(x), x))) stopifnot(identical(unipos(x, order="values"), match.integer64(unique(x, order="values"), x))) stopifnot(identical(unique(x), x[unipos(x)])) stopifnot(identical(unique(x, order="values"), x[unipos(x, order="values")]))
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