Claire Eddy alarmed me a few days back by telling me about a website that diagrams sentences. “They can’t possibly!” I said. “The best AIs we have couldn’t handle that, and Fowler Himself says you can’t diagram the English subjunctive.”
Things cleared up when I looked at the site. They have samples of diagrammed sentences, and they’ll diagram a sentence if you send it to them, but they haven’t tried to make it an automated process. That’s feasible. I can live with it.
While I’m no great fan of diagramming sentences, I have to admit it’s as good a site as you could put together, given the subject. For one thing, they quote from Dave Barry’s “Ask Mr. Language Person”:
Q. Please explain how to diagram a sentence.And, in a virtuoso display of sentence-diagramming macho, they diagram The Pledge of Allegiance and the Preamble to the Constitution.
A. First spread the sentence out on a clean, flat surface, such as an ironing board. Then, using a sharp pencil or X-Acto knife, locate the “predicate,” which indicates where the action has taken place and is usually located directly behind the gills. For example, in the sentence: “LaMont never would of bit a forest ranger,” the action probably took place in a forest. Thus your diagram would be shaped like a little tree with branches sticking out of it to indicate the locations of the various particles of speech, such as your gerunds, proverbs, adjutants, etc.