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Hash join: Difference between revisions
rearranges in order of the language.
m (→{{header|zkl}}: misc) |
(rearranges in order of the language.) |
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[ [ 18 "Alan" ] [ "Alan" "Zombies" ] ]
[ [ 28 "Glory" ] [ "Glory" "Buffy" ] ]
</pre>▼
=={{header|Erlang}}==▼
<lang Erlang>▼
-module( hash_join ).▼
-export( [task/0] ).▼
task() ->▼
Table_1 = [{27, "Jonah"}, {18, "Alan"}, {28, "Glory"}, {18, "Popeye"}, {28, "Alan"}],▼
Table_2 = [{"Jonah", "Whales"}, {"Jonah", "Spiders"}, {"Alan", "Ghosts"}, {"Alan", "Zombies"}, {"Glory", "Buffy"}],▼
Dict = lists:foldl( fun dict_append/2, dict:new(), Table_1 ),▼
lists:flatten( [dict_find( X, Dict ) || X <- Table_2] ).▼
dict_append( {Key, Value}, Acc ) -> dict:append( Value, {Key, Value}, Acc ).▼
dict_find( {Key, Value}, Dict ) -> dict_find( dict:find(Key, Dict), Key, Value ).▼
dict_find( error, _Key, _Value ) -> [];▼
dict_find( {ok, Values}, Key, Value ) -> [{X, {Key, Value}} || X <- Values].▼
</lang>▼
{{out}}▼
<pre>▼
15> hash_join:task().▼
[{{27,"Jonah"},{"Jonah","Whales"}},▼
{{27,"Jonah"},{"Jonah","Spiders"}},▼
{{18,"Alan"},{"Alan","Ghosts"}},▼
{{28,"Alan"},{"Alan","Ghosts"}},▼
{{18,"Alan"},{"Alan","Zombies"}},▼
{{28,"Alan"},{"Alan","Zombies"}},▼
{{28,"Glory"},{"Glory","Buffy"}}]▼
</pre>
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</lang>
▲=={{header|Erlang}}==
▲<lang Erlang>
▲-module( hash_join ).
▲-export( [task/0] ).
▲task() ->
▲ Table_1 = [{27, "Jonah"}, {18, "Alan"}, {28, "Glory"}, {18, "Popeye"}, {28, "Alan"}],
▲ Table_2 = [{"Jonah", "Whales"}, {"Jonah", "Spiders"}, {"Alan", "Ghosts"}, {"Alan", "Zombies"}, {"Glory", "Buffy"}],
▲ Dict = lists:foldl( fun dict_append/2, dict:new(), Table_1 ),
▲ lists:flatten( [dict_find( X, Dict ) || X <- Table_2] ).
▲dict_append( {Key, Value}, Acc ) -> dict:append( Value, {Key, Value}, Acc ).
▲dict_find( {Key, Value}, Dict ) -> dict_find( dict:find(Key, Dict), Key, Value ).
▲dict_find( error, _Key, _Value ) -> [];
▲dict_find( {ok, Values}, Key, Value ) -> [{X, {Key, Value}} || X <- Values].
▲</lang>
▲{{out}}
▲<pre>
▲15> hash_join:task().
▲[{{27,"Jonah"},{"Jonah","Whales"}},
▲ {{27,"Jonah"},{"Jonah","Spiders"}},
▲ {{18,"Alan"},{"Alan","Ghosts"}},
▲ {{28,"Alan"},{"Alan","Ghosts"}},
▲ {{18,"Alan"},{"Alan","Zombies"}},
▲ {{28,"Alan"},{"Alan","Zombies"}},
▲ {{28,"Glory"},{"Glory","Buffy"}}]
▲</pre>
=={{header|Go}}==
Line 981:
28 4 Glory 35 Buffy
</pre>
=={{header|Oberon-2}}==
Works with oo2c version 2
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28 Glory Buffy
</pre>
=={{header|OCaml}}==
This exploits the fact that Hashtbl implements a hash table that can store multiple values for a key, for an especially simple solution:
Line 1,474 ⟶ 1,476:
[[28, "Glory"], ["Glory", "Buffy"]]
</pre>
=={{header|Scala}}==
<lang Scala>def join[Type](left: Seq[Seq[Type]], right: Seq[Seq[Type]]) = {
Line 1,502 ⟶ 1,505:
List(28, Alan, Ghosts)
List(28, Alan, Zombies)</pre>
=={{header|Scheme}}==
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