I made an edit to a question and the portion mentioning the n-gram chart was reverted. I was reading the Wikipedia article about n-grams and added the hyphen based on that usage. This article says Ngram is just Google’s branding for its Ngram Viewer tool. Which spelling is correct?
In my mind n-gram should refer to the word phrase, and Ngram should be rephrased to Ngram comparison when referring to a chart showing the comparison of n-grams.