n/a
There is a filter method on iterators. For example to get only odd numbers in a list:
val it = Iterator(1, 2, 4, 3, 7, 8)
val it1 = it.filter(_ % 2 == 1)
it1.foreach(println)
// 1
// 3
// 7
regards,
Siddhartha
I’m not sure what you mean by punctuation?
You want only some of the chars (like only digits and letters)?
you can use Iterator.filter or Iterator.filterNot
and predicates on Char: isDigit, isControl, isLetter, isLetterOrDigit, and so on…
“Andy Jones”, you can use piazza and I have office hours too… 
Expanding on the above: as you’re getting used to the idea of higher-order functions, I recommend doing a lot of playing with .filter() (filter out some of the elements) and .map() (transform each element into something else), which in my experience tend to be the most commonly-useful ones.
There are a bajillion little ways to use these, most of them little one-liners like this – the surprising bit is often how concise the results are. For example, depending on how you define it, the answer to your question might be as simple as it.filter(_.isLetterOrDigit). (As shown here.)
More questions welcomed…