this can be simplified (and will work with older perl-versions)

perl -F':' -lane '
push @{$h{$F[1]}}, [$F[0],$_] }{
print $_->[1] for map { ( sort {$b->[0] <=> $a->[0]} @$_ )[0..3] } val
+ues %h' file
20470:ZM:Samfya:Africa
20149:ZM:Sesheke:Africa
18638:ZM:Siavonga:Africa

699385:ZW:Bulawayo:Africa
61739:ZW:Chinhoyi:Africa
47294:ZW:Chegutu:Africa
37423:ZW:Bindura:Africa

[download]

Please note that countries with less than 4 cities will have empty lines.

But I'd rather prefer chaining only maps...

Cheers Rolf

( addicted to the Perl Programming Language)

update

to avoid empty lines skip the -l option

perl -F':' -ane '
push @{$h{$F[1]}}, [$F[0],$_] }{
print $_->[1] for map { ( sort {$b->[0] <=> $a->[0]} @$_ )[0..3] } val
+ues %h' file
20470:ZM:Samfya:Africa
20149:ZM:Sesheke:Africa
18638:ZM:Siavonga:Africa
699385:ZW:Bulawayo:Africa
61739:ZW:Chinhoyi:Africa
47294:ZW:Chegutu:Africa
37423:ZW:Bindura:Africa

[download]

elaboration

values instead of keys

(List)[slice] instead of splice

-l chomps and sets auto-newline in $\

In reply to Re^5: Using map function to print few elements of list returned by sort function by LanX
in thread Using map function to print few elements of list returned by sort function by jaypal

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