Core sorted-merge algorithm for as-of join.
Part 1 — asof-search / asof-indices: asof-search — binary search for the last right index where value <= target. asof-indices — two-pointer merge over pre-sorted, pre-grouped vectors; public utility, not used internally by asof-match.
Part 2 — asof-match: full key-handling layer. Groups right rows by exact keys, sorts within each group, runs asof-search (binary search) per left row. Returns a lazy sequence of [left-row-idx right-row-idx-or-nil] pairs.
Part 3 — build-result: assembles a tech.v3.dataset from the index pairs. Left columns always present in original order; right non-key columns appended (nil-filled for unmatched rows). Conflicting non-key column names suffixed :right.<n>.
Core sorted-merge algorithm for as-of join.
Part 1 — asof-search / asof-indices:
asof-search — binary search for the last right index where value <= target.
asof-indices — two-pointer merge over pre-sorted, pre-grouped vectors;
public utility, not used internally by asof-match.
Part 2 — asof-match: full key-handling layer. Groups right rows by exact
keys, sorts within each group, runs asof-search (binary search) per left
row. Returns a lazy sequence of [left-row-idx right-row-idx-or-nil] pairs.
Part 3 — build-result: assembles a tech.v3.dataset from the index pairs.
Left columns always present in original order; right non-key columns
appended (nil-filled for unmatched rows). Conflicting non-key column
names suffixed :right.<n>.(asof-indices left-vals right-vals)Two-pointer merge: for each element in left-vals, return a long-array
of the matched right-row index within right-vals (both must be pre-sorted
ascending). Returns -1 for left rows with no match. Nil values are skipped.
Public utility — not used internally by asof-match, which uses asof-search (binary search per group) instead.
Two-pointer merge: for each element in `left-vals`, return a long-array of the matched right-row index within `right-vals` (both must be pre-sorted ascending). Returns -1 for left rows with no match. Nil values are skipped. Public utility — not used internally by asof-match, which uses asof-search (binary search per group) instead.
(asof-match left right left-keys right-keys)Produce index pairs for an as-of join.
Arguments: left — tech.v3.dataset right — tech.v3.dataset left-keys — vector of column keywords; last = asof col, rest = exact cols right-keys — vector of column keywords; same structure
Returns a lazy sequence of [left-row-idx right-row-idx-or-nil] pairs in left-row order. Unmatched left rows (no exact-key group, or asof-key earlier than all right asof-keys for that group) yield nil for right index.
Produce index pairs for an as-of join. Arguments: left — tech.v3.dataset right — tech.v3.dataset left-keys — vector of column keywords; last = asof col, rest = exact cols right-keys — vector of column keywords; same structure Returns a lazy sequence of [left-row-idx right-row-idx-or-nil] pairs in left-row order. Unmatched left rows (no exact-key group, or asof-key earlier than all right asof-keys for that group) yield nil for right index.
(asof-search right-vals n target)Binary search: find the last index in sorted right-vals where value <= target.
Nils in right-vals are treated as greater than any real value (they sort last),
so a nil at mid causes the search to go left, not right.
Returns -1 if no such element exists. Nil target returns -1.
Binary search: find the last index in sorted `right-vals` where value <= `target`. Nils in right-vals are treated as greater than any real value (they sort last), so a nil at mid causes the search to go left, not right. Returns -1 if no such element exists. Nil target returns -1.
(build-result left right pairs right-keys)Assemble the as-of join result dataset from index pairs.
Arguments: left — tech.v3.dataset (all rows preserved, in original order) right — tech.v3.dataset pairs — seq of [left-row-idx right-row-idx-or-nil] right-keys — right key columns (dropped from the appended right columns)
Returns a dataset with:
Assemble the as-of join result dataset from index pairs. Arguments: left — tech.v3.dataset (all rows preserved, in original order) right — tech.v3.dataset pairs — seq of [left-row-idx right-row-idx-or-nil] right-keys — right key columns (dropped from the appended right columns) Returns a dataset with: - all left columns in original order - right non-key columns appended (nil-filled for unmatched rows) - conflicting non-key column names suffixed with :right.<n>
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