in reply to Re: Using map function to print few elements of list returned by sort function
in thread Using map function to print few elements of list returned by sort function

Sorry to bug you with a follow up question. Is there a way we can nest two for loops in one line. For eg : 

for $k (sort keys %h) {
  print $_->[1] for splice [sort {$b->[0]<=>$a->[0]} @{$h{$k}}], 0, 4
}

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could be written something like: 

print $_->[1] for splice [sort {$b->[0]<=>$a->[0]} @{$h{$k}}], 0, 4 fo
+r keys %h

[download]

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Re^3: Using map function to print few elements of list returned by sort function
by LanX (Saint) on May 25, 2014 at 23:02 UTC
    No, but you can chain maps.

    Cheers Rolf

    ( addicted to the Perl Programming Language)

[reply]

      With your hint, I was able to do the following 

      perl -F':' -lane '
push @{$h{$F[1]}}, [$F[0],$_] }{
print $_->[1] for map { splice [sort {$b->[0] <=> $a->[0]} @{$h{$_}}],
+0,4 } keys %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]

      Thanks LanX, your guidance was much appreciated.

[reply]
[d/l]
        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 $\

[reply]
[d/l]
[select]

      Thanks LanX for the hint. Will try it out now.

[reply]

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