Re^2: Combining two .csv files

[naturalsciences]

The files had tables in them like these. Min. file

Site1	Site2
3	4
5	6
5	8

And then a similar looking .max file. I couldn't write a script to combine them to a single file that would contain field that have "min - max" in them. I made a workaround and combined those two .csv files into one. Then I was able to write and use this simple script.

 
#!/usr/bin/perl -w
open IN, "minmaxin.csv" || die ("did not open infile"); 
open OUT, ">>minmaxtoprint.csv" || die ("did not open outfile");

     while (<IN>) {
      my @line = split(/,/, $_);  
print OUT "$line[0]-$line[4],$line[1]-$line[5],$line[2]-$line[6],$line
+[3]-$line[7]";}
close IN;
close OUT;

(As you can see there were four test sites.) Why I made my first post. Is this reason - It is not easy for me to write a script that combines two input files. I have learned as much that i can make simple scripts to modify one file. But regularily I came to a problem like this. A sample code - to illustrate my stupidity/greenness.

#!/usr/bin/perl -w
open MIN, "min.csv" || die ("did not open infile");
open MAX "max.csv" || die ("did not open infile");
open OUT, ">>minmaxtoprint.csv" || die ("did not open outfile");

     while (<MIN>) {
      my @minline = split(/,/, $_);
while (<MAX>){my @maxline = split(/,/, $_);}, print OUT "$minline[0]$l
+ine[0] ... etc

Which will obviously not work. The problem is more genral actually - how to I iterate through elements of one entity (file, array etc) while adding/substracting/interacting with elements corresponding to another? That is a thing I would very much like to learn.

To learn is the reason I joined this site, I'm right now in my "knowledge" of perl only limited to what stuff I have been able to find online. I have had no teacher whatsoever :(