Re: Round numbers?

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
[download]

Update: This loop produces the same output without needing an intermediate variable:

printf qq{%5.*g \n}, $_ > 0.001 ? 2 : 3, $_ for @nra;
[download]

Comment on Re: Round numbers? Select or Download Code

Replies are listed 'Best First'.
Re^2: Round numbers? by Anonymous Monk on Oct 01, 2009 at 23:48 UTC
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; }` [download] It's like: `for my $n (@nra) { my $fmt=$n; if($n>0.001){ ????? } else { ?????? } printf qq{$fmt \n}, $n; }` [download] Thank you for your time!	[reply] [d/l] [select]
Re^3: Round numbers? by AnomalousMonk (Archbishop) on Oct 02, 2009 at 00:05 UTC
No, like: `for my $n (@nra) { my $fmt; if ($n > 0.001){ $fmt = '%5.2g'; } else { $fmt = '%5.3g'; } printf qq{$fmt \n}, $n; }` [download] See Conditional Operator in perlop. Note that `$x = $y > $z ? 'foo' : 'bar';` is perhaps more clearly written as `$x = ($y > $z) ? 'foo' : 'bar';`	[reply] [d/l] [select]
Re^4: Round numbers? by Anonymous Monk on Oct 02, 2009 at 00:51 UTC
A million thanx to you! It was very kind you explained all that to me!	[reply]