# 64-bit integer matching `match` returns a vector of the positions of (first) matches of its first argument in its second. `%in%` is a more intuitive interface as a binary operator, which returns a logical vector indicating if there is a match or not for its left operand. ```r ## S3 method for class 'integer64' match(x, table, nomatch = NA_integer_, nunique = NULL, method = NULL, ...) ## S3 method for class 'integer64' x %in% table, ... ``` ## Arguments - `x`: integer64 vector: the values to be matched, optionally carrying a cache created with `hashcache` - `table`: integer64 vector: the values to be matched against, optionally carrying a cache created with `hashcache` or `sortordercache` - `nomatch`: the value to be returned in the case when no match is found. Note that it is coerced to integer. - `nunique`: NULL or the number of unique values of table (including NA). Providing `nunique` can speed-up matching when `table` has no cache. Note that a wrong nunique can cause undefined behaviour up to a crash. - `method`: NULL for automatic method selection or a suitable low-level method, see details - ``...``: ignored ## Details These functions automatically choose from several low-level functions considering the size of `x` and `table` and the availability of caches. Suitable methods for `%in%.integer64` are `hashpos` (hash table lookup), `hashrev` (reverse lookup), `sortorderpos` (fast ordering) and `orderpos` (memory saving ordering). Suitable methods for `match.integer64` are `hashfin` (hash table lookup), `hashrin` (reverse lookup), `sortfin` (fast sorting) and `orderfin` (memory saving ordering). ## Returns A vector of the same length as `x`. `match`: An integer vector giving the position in `table` of the first match if there is a match, otherwise `nomatch`. If `x[i]` is found to equal `table[j]` then the value returned in the `i`-th position of the return value is `j`, for the smallest possible `j`. If no match is found, the value is `nomatch`. `%in%`: A logical vector, indicating if a match was located for each element of `x`: thus the values are `TRUE` or `FALSE` and never `NA`. ## Author(s) Jens Oehlschlägel ## See Also `match` ## Examples ```r x <- as.integer64(c(NA, 0:9), 32) table <- as.integer64(c(1:9, NA)) match.integer64(x, table) "%in%.integer64"(x, table) x <- as.integer64(sample(c(rep(NA, 9), 0:9), 32, TRUE)) table <- as.integer64(sample(c(rep(NA, 9), 1:9), 32, TRUE)) stopifnot(identical(match.integer64(x, table), match(as.integer(x), as.integer(table)))) stopifnot(identical("%in%.integer64"(x, table), as.integer(x) %in% as.integer(table))) ## Not run: message("check when reverse hash-lookup beats standard hash-lookup") e <- 4:24 timx <- timy <- matrix(NA, length(e), length(e), dimnames=list(e,e)) for (iy in seq_along(e)) for (ix in 1:iy){ nx <- 2^e[ix] ny <- 2^e[iy] x <- as.integer64(sample(ny, nx, FALSE)) y <- as.integer64(sample(ny, ny, FALSE)) #hashfun(x, bits=as.integer(5)) timx[ix,iy] <- repeat.time({ hx <- hashmap(x) py <- hashrev(hx, y) })[3] timy[ix,iy] <- repeat.time({ hy <- hashmap(y) px <- hashpos(hy, x) })[3] #identical(px, py) print(round(timx[1:iy,1:iy]/timy[1:iy,1:iy], 2), na.print="") } message("explore best low-level method given size of x and table") B1 <- 1:27 B2 <- 1:27 tim <- array(NA, dim=c(length(B1), length(B2), 5) , dimnames=list(B1, B2, c("hashpos","hashrev","sortpos1","sortpos2","sortpos3"))) for (i1 in B1) for (i2 in B2) { b1 <- B1[i1] b2 <- B1[i2] n1 <- 2^b1 n2 <- 2^b2 x1 <- as.integer64(c(sample(n2, n1-1, TRUE), NA)) x2 <- as.integer64(c(sample(n2, n2-1, TRUE), NA)) tim[i1,i2,1] <- repeat.time({h <- hashmap(x2);hashpos(h, x1);rm(h)})[3] tim[i1,i2,2] <- repeat.time({h <- hashmap(x1);hashrev(h, x2);rm(h)})[3] s <- clone(x2); o <- seq_along(s); ramsortorder(s, o) tim[i1,i2,3] <- repeat.time(sortorderpos(s, o, x1, method=1))[3] tim[i1,i2,4] <- repeat.time(sortorderpos(s, o, x1, method=2))[3] tim[i1,i2,5] <- repeat.time(sortorderpos(s, o, x1, method=3))[3] rm(s,o) print(apply(tim, 1:2, function(ti)if(any(is.na(ti)))NA else which.min(ti))) } ## End(Not run) ```

match.integer64.rd function