Hash join: Difference between revisions
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(→Tcl: Added implementation) |
(→{{header|Tcl}}: Some extra notes) |
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=={{header|Tcl}}== |
=={{header|Tcl}}== |
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Tcl uses hash tables to implement both its associative arrays and its dictionaries. |
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<lang tcl>package require Tcl 8.6 |
<lang tcl>package require Tcl 8.6 |
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# Only for lmap, which can be replaced with foreach |
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proc joinTables {tableA indexA tableB indexB} { |
proc joinTables {tableA indexA tableB indexB} { |
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foreach value $tableA { |
foreach value $tableA { |
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set hashmap([lindex $value $indexA]) $value |
set hashmap([lindex $value $indexA]) $value |
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#dict version# dict set hashmap [lindex $value $indexA] $value |
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} |
} |
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lmap value $tableB { |
lmap value $tableB { |
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set key [lindex $value $indexB] |
set key [lindex $value $indexB] |
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if {![info exist hashmap($key)]} continue |
if {![info exist hashmap($key)]} continue |
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#dict version# if {![dict exists $hashmap $key]} continue |
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list $hashmap($key) $value |
list $hashmap($key) $value |
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#dict version# list [dict get $hashmap $key] $value |
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} |
} |
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} |
} |
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