Still very stuck on this one if anyone can provide more code/help it would be most appreciated. Thanks Dave

Hi I have a parsing issue that I was wondering if someone can please help me out. Thanks for your consideration Dave If I have a data file like below: 

$start $stop $id1 $id2
1    100    1    2
101    200    1    2
201    300    1    0
301    400    1    0
401    500    0    2
501    600    0    2
601    700    0    0
701    800    1    1
801    900    1    2

[download]

I want to go down each column $id1 and $id2 and replacing the zeros '0' in a block of zeros with a number only if the number before and after the end zero blocks are the same, eg: the results would be: 

1    100    1    2
101    200    1    2
201    300    1    2
301    400    1    2
401    500    1    2
501    600    1    2
601    700    1    0
701    800    1    1
801    900    1    2

[download]
here is some code I started off: 
while(<>){
chomp;
($start, $stop, $id1, $id2)=split(/\t/,$_);





$old_id1=$id1;
$old_id2=$id2;

}

[download]

In reply to filling in the zeros...please help by david_lyon

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