Shell Programming and Scripting

Hi,

I need to match up some numbers in one file to the closest numbers in other file and produce an output file.

File one (f1.txt) is laid out like this
etc,,,,

File two (F2.txt) is liad out like this
etc,,,

And I would like the output file to read
As you can see I need to find the closest match from collumn 2 on boths files and collumn 3 on both files and output the above.


Many thanks,
Ian

What you are asking requires substantial logic. How do you determine 'close enough'
We need an exact statement of how you intend to determine 'closeness' and what to do when no close match is found.

Is it 1%? You cannot just 'eyeball' data with programming languages easily.

Hi Jim,

Perhaps nearest should be the key. How I'm thinking is that as the files are looping the nearest match can be found and that is the one to use.

So $2 on file one has a number of 53.728563 and the nearest match on $2 on file two is 53.78.
Once that number has been found then loop though $3 on both files, but only look at the 53.78 numbers (the number we found on $2) there will be quite a few on file 2 and return then nearest match which would be -2.44 and print out the rest..........

I dont think I'm making this sound easy am I? But please stay with me on this :-)

Cheers,
Ian

---------- Post updated at 01:17 PM ---------- Previous update was at 01:07 PM ----------

Hang on.....I will try and explain this again..

If I have one file called A.txt with
1
2
3
4
5
And I have another with
1.1
2.1
1.3
5.1
0.9
Is it possible to return a output file like this
1 0.9
1 1.1
1 1.3
2 2.1
5 5.1

As you can see I have matched up the nearest number from one file to another... I'm not sure whether this is possible to do, but this is what I desire :-)

Many thanks for looking at this

Cheers,
Ian

Code:

open $fh,"<f1.txt";
while(<$fh>){
	chomp;
	my @arr = split;
	$hash{$arr[2]}->{'SEQ'}=$.;
	$hash{$arr[2]}->{'VAL'}=$_;
	$hash{$arr[2]}->{'GAP'}=10000;
}
open $fh2,"<f2.txt";
while(<$fh2>){
	my @tmp = split;
	foreach my $key(keys %hash){
		my $new_gap = abs($key-$tmp[1]);
		if($new_gap < $hash{$key}->{'GAP'}){
			$hash{$key}->{'GAP'} = $new_gap;
			$hash{$key}->{'APPEND'}=$tmp[1]." ".$tmp[2]." ".$tmp[0];
		}
	}
}
foreach my $key(sort {$hash{$a}->{'SEQ'} <=> $hash{$b}->{'SEQ'}} keys %hash){
	print $hash{$key}->{'VAL'}," ", $hash{$key}->{'APPEND'},"\n";
}

Hi Summer,

thanks for the script. I have not really tried perl, only bits and bobs, nothing major. I will have a go at it though, if you don't mind coaching me along every now and again. :-)