CODEWITHSUNDEEP
perlprintfmultiple-columns
mzg
mzg

Reputation: 13

using printf to create columnar data

I am new to perl and scripting in general. I have five variables that hold data and I need to print them as five columns next to each other. Here is the code I have now. 

$i = 0;
foreach $line (<inf>){
    chomp $line;
    @line=split / +/, $line;
    $i = $i + 1;
    if ($i > $n+1) {
        $i = 1;
        $numdata = $numdata + 1;
    }
    if ($i == 1) {
        printf "%20s\n", $n, "\n";
    } else {
        print  $i-1, "BEAD", $line[$col], $line[$col+1], $line[$col+2], "\n";
    }
    # other statistics
}

The output I get from this looks like:

                   5
1BEAD0.00000e+000.00000e+000.00000e+00
2BEAD0.00000e+000.00000e+000.00000e+00
3BEAD0.00000e+000.00000e+000.00000e+00
4BEAD0.00000e+000.00000e+000.00000e+00
5BEAD0.00000e+000.00000e+000.00000e+00
                   5
1BEAD9.40631e-02-3.53254e-022.09369e-01
2BEAD-6.69662e-03-3.13492e-012.62915e-01
3BEAD2.98822e-024.60254e-023.61680e-01
4BEAD-1.45631e-013.45979e-021.50167e-01
5BEAD-5.57204e-02-1.51673e-012.95947e-01
                   5
1BEAD8.14225e-028.10216e-022.76423e-01
2BEAD2.36992e-02-2.74023e-014.47334e-01
3BEAD1.23492e-011.12571e-012.59486e-01
4BEAD-2.05375e-011.25304e-011.85252e-01
5BEAD5.54441e-02-1.30280e-015.82256e-01

I have tried using "%6d %9d %15.6f %28.6f %39.6f\n" before the variables in my print statement to try to space the data out; however, this did not give me the columns I hoped for. Any help/ suggestions are appreciated.

Upvotes: 1

Views: 90

Answers (1)

cincodenada
cincodenada

Reputation: 3087

If you're using Perl and doing more complex stuff, you may want to look into perlform, which is designed for this kind of thing, or a module like Text::Table.

As for using printf though, you can use the padding specifiers to get consistent spacing. For instance, using the Perl docs on it, make sure the field width is before the .: your printf string should probably look something more like this (check out the "precision, or maximum width" section):

printf "%6.d %9.d %15.6f %28.6f %39.6f"

Also, if your things are in an array, you can just pass the array the second argument to printf and save yourself typing everything out. I've also prepended the two other items from your example with unshift:

unshift(@line, $i-1, "BEAD");
printf "%6.d %10s %15.6f %28.6f %39.6f\n", $line;

Note that the %s placeholders don't have the . precision specifier, so leave it out for that. If you want the e-notation for the numbers, use %e or %g instead of %f (%39.6e).

Also, for Perl questions, always check out Perl Monks - much of this answer was culled from a question there.

P.S. Given one of your example columns, here's the proof-of-concept script I tried to make sure everything worked:

perl -e '@line = (8.14225e-02,8.10216e-02,2.76423e-01);
    unshift(@line, 4, "BEAD");
    printf "%6.d %10s %15.6f %28.6f %39.6e\n", @line;'

Upvotes: 1

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