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merge.data.table = function(x, y, by = NULL, by.x = NULL, by.y = NULL, all = FALSE, all.x = all,
all.y = all, sort = TRUE, suffixes = c(".x", ".y"), no.dups = TRUE, allow.cartesian=getOption("datatable.allow.cartesian"), incomparables=NULL, ...) {
if (!sort %in% c(TRUE, FALSE))
stopf("Argument 'sort' should be logical TRUE/FALSE")
if (!no.dups %in% c(TRUE, FALSE))
stopf("Argument 'no.dups' should be logical TRUE/FALSE")
class_x = class(x)
if (!is.data.table(y)) {
y = as.data.table(y)
if (missing(by) && missing(by.x)) {
by = key(x)
}
}
x0 = length(x)==0L
y0 = length(y)==0L
if (x0 || y0) {
if (x0 && y0)
warningf("Neither of the input data.tables to join have columns.")
else if (x0)
warningf("Input data.table '%s' has no columns.", "x")
else
warningf("Input data.table '%s' has no columns.", "y")
}
nm_x = names(x)
nm_y = names(y)
if (anyDuplicated(nm_x)) stopf("%s has some duplicated column name(s): %s. Please remove or rename the duplicate(s) and try again.", "x", brackify(nm_x[duplicated(nm_x)]))
if (anyDuplicated(nm_y)) stopf("%s has some duplicated column name(s): %s. Please remove or rename the duplicate(s) and try again.", "y", brackify(nm_y[duplicated(nm_y)]))
## set up 'by'/'by.x'/'by.y'
if ( (!is.null(by.x) || !is.null(by.y)) && length(by.x)!=length(by.y) )
stopf("`by.x` and `by.y` must be of same length.")
if (!missing(by) && !missing(by.x))
warningf("Supplied both `by` and `by.x/by.y`. `by` argument will be ignored.")
if (!is.null(by.x)) {
if (length(by.x)==0L || !is.character(by.x) || !is.character(by.y))
stopf("A non-empty vector of column names is required for `by.x` and `by.y`.")
if (!all(by.x %chin% nm_x))
stopf("Elements listed in `by.x` must be valid column names in x.")
if (!all(by.y %chin% nm_y))
stopf("Elements listed in `by.y` must be valid column names in y.")
by = by.x
names(by) = by.y
} else {
if (is.null(by))
by = intersect(key(x), key(y))
if (!length(by)) # was is.null() before PR#5183 changed to !length()
by = key(x)
if (!length(by))
by = intersect(nm_x, nm_y)
if (length(by) == 0L || !is.character(by))
stopf("A non-empty vector of column names for `by` is required.")
if (!all(by %chin% intersect(nm_x, nm_y)))
stopf("Elements listed in `by` must be valid column names in x and y")
by = unname(by)
by.x = by.y = by
}
# warn about unused arguments #2587
if (length(list(...))) {
ell = as.list(substitute(list(...)))[-1L]
for (n in setdiff(names(ell), "")) warningf("Unknown argument '%s' has been passed.", n)
unnamed_n = length(ell) - sum(nzchar(names(ell)))
if (unnamed_n)
warningf("Passed %d unknown and unnamed arguments.", unnamed_n)
}
# with i. prefix in v1.9.3, this goes away. Left here for now ...
## sidestep the auto-increment column number feature-leading-to-bug by
## ensuring no names end in ".1", see unit test
## "merge and auto-increment columns in y[x]" in test-data.frame.like.R
start = setdiff(nm_x, by.x)
end = setdiff(nm_y, by.y)
dupnames = intersect(start, end)
if (length(dupnames)) {
start[chmatch(dupnames, start, 0L)] = paste0(dupnames, suffixes[1L])
end[chmatch(dupnames, end, 0L)] = paste0(dupnames, suffixes[2L])
}
# If no.dups = TRUE we also need to added the suffix to columns in y
# that share a name with by.x
dupkeyx = intersect(by.x, end)
if (no.dups && length(dupkeyx)) {
end[chmatch(dupkeyx, end, 0L)] = paste0(dupkeyx, suffixes[2L])
}
# implement incomparables argument #2587
if (!is.null(incomparables)) {
# %fin% to be replaced when #5232 is implemented/closed
"%fin%" = function(x, table) if (is.character(x) && is.character(table)) x %chin% table else x %in% table
xind = rowSums(x[, lapply(.SD, function(x) !(x %fin% incomparables)), .SDcols=by.x]) == length(by)
yind = rowSums(y[, lapply(.SD, function(x) !(x %fin% incomparables)), .SDcols=by.y]) == length(by)
# subset both so later steps still work
x = x[xind]
y = y[yind]
}
dt = y[x, nomatch=if (all.x) NA else NULL, on=by, allow.cartesian=allow.cartesian] # includes JIS columns (with a i. prefix if conflict with x names)
if (all.y && nrow(y)) { # If y does not have any rows, no need to proceed
# Perhaps not very commonly used, so not a huge deal that the join is redone here.
missingyidx = y[!x, which=TRUE, on=by, allow.cartesian=allow.cartesian]
if (length(missingyidx)) dt = rbind(dt, y[missingyidx], use.names=FALSE, fill=TRUE, ignore.attr=TRUE)
}
# X[Y] syntax puts JIS i columns at the end, merge likes them alongside i.
newend = setdiff(nm_y, by.y)
# fix for #1290, make sure by.y order is set properly before naming
setcolorder(dt, c(by.y, setdiff(names(dt), c(by.y, newend)), newend))
setnames(dt, c(by.x, start, end))
if (nrow(dt) > 0L) {
setkeyv(dt, if (sort) by.x else NULL)
}
# Throw warning if there are duplicate column names in 'dt' (i.e. if
# `suffixes=c("","")`, to match behaviour in base:::merge.data.frame)
resultdupnames = names(dt)[duplicated(names(dt))]
if (length(resultdupnames)) {
warningf("column names %s are duplicated in the result", brackify(resultdupnames))
}
# retain custom classes of first argument that resulted in dispatch to this method, #1378
setattr(dt, "class", class_x)
dt
}
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