is there anyway to reduce the amount of numbers in legend?

Hi everyone, I'm trying to create color legend based on the distance between all the grid point and the two boxes, but it seems has too much color codes in one chart, the legend is unreadable. Is there anyway that I can resort all the numbers, keep the gradient color, but keep them in a more smooth way, like the chart in excel, or export the data into excel, so I can read it better, made the legend useful.

Thanks