Purple is an interesting color to dissect because it’s only shown once; within the space of Room 237, immediately amping up it’s meaning.
It could be a mixture of red, white, and blue (see: American History), it could equally be a mixture of red and blue (rage and sadness).
Historically, Purple has come to represent wealth and royalty which would sardonically back up No.11’s comment that “All the best people” have stayed within The Overlook’s walls.
In this image · No.48
Green and Purple
Green repeats throughout the suite, especially the light green. Purple is unusually prominent here; the notes propose reading it as a mixture of red, white, and blue.