More so than many genres of music, rap is based around words. They hold a special importance. It's why there are full books and websites dedicated to lyrics alone.
To help quantify some of the the variance in words that rappers use, Matt Daniels, who is a coder, designer and data scientist, put together a project he called "The Largest Vocabulary in Hip Hop." To do this, he compiled dozens of rappers' first 35,000 lyrics, using the website RapGenius, and sought to determine which MC had the largest vocab.
"I used a research methodology called token analysis to determine each artist’s vocabulary," he exlpains on his site. "Each word is counted once, so pimps, pimp, pimping, and pimpin are four unique words. To avoid issues with apostrophes (e.g., pimpin’ vs. pimpin), they’re removed from the dataset. It still isn’t perfect. Hip hop is full of slang that is hard to transcribe (e.g., shorty vs. shawty), compound words (e.g., king sh--), featured vocalists, and repetitive choruses.
Some of the results are surprising. For instance, Eminem, at 4,494 unique words, used less than 100 more than Diddy. Bone Thugs-N-Harmony, with their rapid fire deliveries, were fourth to last on the list.
Others aren't quite as jarring, like the fact that members of Wu-Tang Clan, Outkast and Kool G Rap were all near the top in terms of unique words used.
Head over to Daniels' site for the entire interactive project