Hi Lakssreedhar
Use a 2D array to read a file column wise. Then adopt the folowing steps :
1. count the number of lines of your file.
2. Use some regular expression to split the file with respect to the column delimiters i.e tab in your case .
Thus build the 2D array.
3. Use a sub routine to get all the values of the 9th column and push them in an array.
4. Process the array to look where at which index I is preceded by O. Find those indexes.
5. open your data file again and using the 2D matrix just replace those positions .
The following code could be a bit help to you
my @matrix;
my $row = 0;
# count no. of lines
open(DATA, "< data.txt");
my @lines = <DATA>;
close(DATA);
my $c = @lines;
open(DATA, "< data.txt");
push @{$matrix[$row++]}, split while <DATA>;
dd @matrix;
&colprint(\@matrix);
close(DATA);
my @arrayOfninth_col;
sub colprint
{
my $matrix_ref = shift;
for (1 .. $c)
{
print "$matrix_ref->[$c-1][9] \n";
my $value = $matrix_ref->[$c-1][9];
push @arrayOfninth_col , $value;
}
# process the array @arrayOfninth_col for indexes
}
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