Roy Chanslor had a long and interesting career in Hollywood, but he's probably best known for two western movies made from his novel. One of them was Johnny Guitar. Quick, what was the other one? Don't know? Cat Ballou. The novel was The Ballad of Cat Ballou, which in the movie becomes the song sung by Stubby Kaye and Nat King Cole.
I'd wanted to read Johnny Guitar for a good while, but copies were too hard to come by and too expensive. Not long ago, though, one appeared on eBay and I snapped it up. The book's dedicated to Joan Crawford, and as you can see from the page I've reproduced here, she was ready to star in the movie from the beginning. She'd obviously seen the novel before even the hardcover was published, since the movie came out only a few months after the novel.
I'd hoped the novel would have something of the goofy charm of the movie. No such luck. It's basically a sappy love story, so whoever wrote the screenplay (there's some dispute, I believe) and the director (Nicolas Ray) deserve a lot of credit (if that's the word) for what the movie became. I'm not going to do a point-by-point comparison, but it might be fun if someone had the energy. The book has its moments, but they're few and far between. Given the choice, you should watch the movie.