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Setting up an array and sorting the elements by key
Arrays and dicts example from a Well House Consultants training course
More on Arrays and dicts [link]
Source code: ar_rail Module: T208
# Setting up an array and sorting the elements by key
# 5337 FMR BN1 9PU TQ 346088 50.8621241499 -0.0873836155 Falmer 771095 838150 920259 1009988 1045586 1033392 set fh [open railstats.xyz r] proc byquantity {a b} { global uses # Following line is useful as a demo of how sort works # puts "$a .... $b" return [expr $uses($a) - $uses($b)] } while {[set line [gets $fh]] != ""} { set fields [split $line "\t"] set placename [lindex $fields 6] set passengers [lindex $fields 8] # NULL is not special in Tcl ... it just happens to be a value in # our data file and we wish to elimitate data lines that have it in # the passengers field if {$passengers != "NULL"} { set uses($placename) $passengers } } foreach pl [lsort -command byquantity [array names uses South*]] { puts [format "%8d %s" $uses($pl) $pl] exit # --------------- never gets past here in running # sample results munchkin:ta grahamellis$ tclsh ar_rail 1942 South Bank 6106 South Greenford 7245 Southease 35812 South Wigston 42090 South Tottenham 46146 South Hampstead 50424 South Merton 78239 South Milford 80995 South Acton 135017 Southminster 185022 South Kenton 200700 Southbourne 245667 South Bermondsey 252079 Southwick 263038 Southbury 265547 South Elmsall 424306 South Gyle 772355 South Croydon 797470 Southend East 859286 Southall 1421305 Southampton Airport (Parkway) 1582115 Southport 1719370 Southend Victoria 3018137 Southend Central 4844998 Southampton Central munchkin:ta grahamellis$ } Learn about this subject
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