What is the difference between lemmatization vs stemming?

Question

When do I use each ?

Also...is the NLTK lemmatization dependent upon Parts of Speech? Wouldn\'t it be more accurate if it was?

Answer 1

An example-driven explanation on the differenes between lemmatization and stemming:

Lemmatization handles matching “car” to “cars” along with matching “car” to “automobile”.

Stemming handles matching “car” to “cars” .

Lemmatization implies a broader scope of fuzzy word matching that is still handled by the same subsystems. It implies certain techniques for low level processing within the engine, and may also reflect an engineering preference for terminology.

[...] Taking FAST as an example, their lemmatization engine handles not only basic word variations like singular vs. plural, but also thesaurus operators like having “hot” match “warm”.

This is not to say that other engines don’t handle synonyms, of course they do, but the low level implementation may be in a different subsystem than those that handle base stemming.

http://www.ideaeng.com/stemming-lemmatization-0601