Q:

When parsing text for n-grams - should punctuation be included? 

I want to start working on data-mining by parsing text.  It seems like the best place to start is by processing n-grams out of text to try sentiment analysis. 
Muffins are fine, I wouldn't say I like them though. 

However, I'm curious to know if I should include punctuation or not. ( I plan on starting with 3-grams and working up since I'm not sure 2-grams include enough information for accurate results.) 
Muffins are fine | are fine [,] | I wouldn't say | ....

Since a "," was found, start over at next word after the ",".  Instead of including the punctuation like normal. 
Muffins are fine | are fine , | fine , I | , I wouldn't | ...

Can anyone tell me if this is a bad idea? 

A:

Google ignores punctuation, but there are non-alphanumeric characters that are not ignored. 
For example, search these word/phrases:

tech spec
tech-spec
tech,spec
tech_spec

The search results vary, showing Google does consider some characters significant. 
Also, are you doing this in non-English languages? 
If so, then consider creating n-grams from a certain number of characters, instead of words.  This will lead to better results on many non-English languages, and it's the only way to effectively parse CJK-type languages that don't use significant whitespace. 

A:

Here's a hint: Google doesn't include punctuation in n-grams.