Rename 'character' --> 'blob'

The term 'character' is a bit misleading. Splitting the input string on
whitespace doesn't give you individual characters; you get blobs of
text.
Remove unnecessary assignments

There's no need to do these assignments. Assignment in Ruby happens to
be an expression (so the value of `a = b` is `b`), so the function still
works, but it's cleaner if you just return the result of the call to
`map`. Same deal in the else branch: `blob = blob` is unnecessary.
Remove an extra name

This is a matter of taste; I prefer to not have to name the call the
string.split(" ").
Spelling mistake :)
Pull out op regex test into function

One fewer opportunity to introduce a typo, plus it reads at a higher
level.
Merge pull request #1 from happy4crazy/code-review

Code review :)