There is no purple in the spectrum. Purple is the color you get when you take white light and put it through a filter which blocks the middle part of the spectrum, or when you combine a red and a blue light source.

Really the named rainbow colors should just end at “blue”, or if you like can include one more color name for very dark and intense “indigo” or “violet” or “purplish blue” (pick your favorite one extra name) but Newton wanted to have 7 color names for aesthetic/numerological reasons.

The best we can do at rendering a spectrum on a computer display is something like https://upload.wikimedia.org/wikipedia/en/3/3f/Jacobolus_spe... but the far ends of the spectrum are not possible to render very accurately.