Hash join: Difference between revisions

=={{header|Swift}}==

{{trans|Rust}}

<lang swift>func hashJoin<A, B, K: Hashable>(_ first: [(K, A)], _ second: [(K, B)]) -> [(A, K, B)] {

var map = [K: [B]]()

for (key, val) in second {

map[key, default: []].append(val)

}

var res = [(A, K, B)]()

for (key, val) in first {

guard let vals = map[key] else {

continue

}

res += vals.map({ (val, key, $0) })

}

return res

}

let t1 = [

("Jonah", 27),

("Alan", 18),

("Glory", 28),

("Popeye", 18),

("Alan", 28)

]

let t2 = [

("Jonah", "Whales"),

("Jonah", "Spiders"),

("Alan", "Ghosts"),

("Alan", "Zombies"),

("Glory", "Buffy")

]

print("Age | Character Name | Nemesis")

print("----|----------------|--------")

for (age, name, nemesis) in hashJoin(t1, t2) {

print("\(age) | \(name) | \(nemesis)")

}</lang>

{{out}}

<pre>Age | Character Name | Nemesis

----|----------------|--------

27 | Jonah | Whales

27 | Jonah | Spiders

18 | Alan | Ghosts

18 | Alan | Zombies

28 | Glory | Buffy

28 | Alan | Ghosts

28 | Alan | Zombies</pre>