By the way... if YOU are creating the files.. why not simplify things and write out CSV records, where each line is:
"string tag",x,y,rot

We have a topic on reading CSV text files:
[code] reading a CSV file

EDIT: Oh you are using MatLab written files, as in this post http://forums.sketchucation.com/viewtopic.php?f=180&t=35961&start=30#p319047

From the looks of your code you're interested specifically in blocks of four lines, in which case you may gain some mileage out of the array.slice method by doing the following.

for i in 0..a.length/4 #there are i blocks of four lines machine,x,y,rot = a.slice(i*4,4) #more code end

Thanks Dan.

As explained my example is just an example - you need to tailor it to you needs so 'f' >>> 'machine' with the .3ds added etc...
In you example it much more difficult to read than mine.
Your 'processing' is inside the if...end test when rotation is set, BUT my way will work with less likelihood of massing up - you simply gather the 4 lines of data as I show and use the references you set from them to do your processing for each 'machine'...

Your
machine = "a[0].3ds"
Is simply a string - with no reference to array 'a' at all.
machine = a[0].to_s+".3ds"
Takes the value of the first item in the array 'a' and adds .3ds onto the end of that all as a string...
If you are sure the first item in the array 'a' is a string you don't need the .to_s part a[0]+".3ds" will do...