Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks, I have a list of numbers that can be in format like:
8.8458e-119     
1.06542e-52
2.68e-36
2.91405e-35
0.0190644
0.0205511
0.004

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Is there something you can suggest me that I use to have some more "elegance" appearance, i.e: 
8.84e-119     
1.06e-52
2.68e-36
2.91e-35
0.019
0.02
0.004

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? Note that I have all these number formats and I want to use a command that could apply to all of them. I tried using:
 $rounded = sprintf("%.3f", $number);

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, but it returns all 0 (which is natural of course)... So, can I use something else?

Replies are listed 'Best First'.
Re: Round numbers?
by AnomalousMonk (Archbishop) on Oct 01, 2009 at 23:28 UTC
    See sprintf  %g format specifier: 
    >perl -wMstrict -le
"my @nra = (
 8.8458e-119,
 1.06542e-52,
 2.68e-36,
 2.91405e-35,
 0.0190644,
 0.0205511,
 0.004,
 );
 for my $n (@nra) {
   my $fmt = $n > 0.001 ? '%5.2g' : '%5.3g';
   printf qq{$fmt \n}, $n;
   }
"
8.85e-119
1.07e-052
2.68e-036
2.91e-035
0.019
0.021
0.004

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    Update: This loop produces the same output without needing an intermediate variable: 
    printf qq{%5.*g \n}, $_ > 0.001 ? 2 : 3, $_ for @nra;

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      Because I am new to Perl and don't understand it that much, can you please tell me how these lines interpret?
      for my $n (@nra) {
   my $fmt = $n > 0.001 ? '%5.2g' : '%5.3g';
   printf qq{$fmt \n}, $n;
   }

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      It's like:
      for my $n (@nra) {
    my $fmt=$n;
    if($n>0.001){
                    ?????  
                }
     else
                {
                     ??????
                }
     printf qq{$fmt \n}, $n;
    }

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      Thank you for your time!
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        No, like: 
        for my $n (@nra) {
    my $fmt;
    if ($n > 0.001){
        $fmt = '%5.2g';  
        }
    else {
        $fmt = '%5.3g';
        }
    printf qq{$fmt \n}, $n;
    }

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        See Conditional Operator in perlop.

        Note that
            $x = $y > $z ? 'foo' : 'bar';
        is perhaps more clearly written as
            $x = ($y > $z) ? 'foo' : 'bar';

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