How to record numbers of array elements based on selection comparision criteria

Question

I have many files which has many 2x2 arrays. In the present example I show only one file (file1)

Input file(file1):

1: 6.1703
 541.631 46.0391

2: 6.1930
 537.446 45.9239

3: 6.1931
 177.171 288.579

4: 6.1939
 167.171 298.579

5: 8.2281
 533.686 53.7245

6: 8.6437
 519.219 65.0547

7: 9.0823
 484.191 95.0753

8: 9.3884
 237.75 240.082

9: 9.4701
 167.525 246.234

10: 9.7268
 411.929 70.7877

First, I need to see the value of the position (1,2) of each matrix, and choose it if it is near to 6.1937 and has a large value in the element(2,1). In this example the chosen value should be 6.1930.

Second, I need to choose the lowest value of the position (1,2) of each matrix, which has large value of the element (2,2).In this case, the chosen value is 6.1931

So the output should be like this

 6.1930  6.1931

Answer 1

Perl to the rescue:

#!/usr/bin/perl
use warnings;
use strict;

my $close_to = 6.1937;

my ($close, $lowest);

$/ = q();
while (<>) {
    my @arr = split;
    if ((! defined $close || abs($arr[1] - $close_to) < abs($close - $close_to))
        && $arr[2] > $arr[3]
        ) {
        $close = $arr[1];
    }
    if ((! defined $lowest || $arr[1] < $lowest)
        && $arr[2] < $arr[3]
        ) {
        $lowest = $arr[1];
    }
    if (eof) {
        print "$close $lowest\n";
        undef $close;
        undef $lowest;
    }
}

Save as script.pl, call as script.pl file1 file2 file3...