One trick (old, before the introduction of patterns in Ferret!) is to make a "transparent" mask using your significance values.
Say we have variables "corr" and "sig_corr" which are on the same grid and we want to highlight values above "sigval"
Drop out values above the significance in a checkerboard fashion values below will be filled solidly.
let masked_corr = if sig_corr lt `sigval` or mod(i+j,2) eq 1 then corr
Overlay with a checkerboard mask in monochrome. This works better if you need to use FILL for you underlying plot.
! Only consider locations above the significance level in checkerboard style.
let mask = if sig_corr gt `sigval` and mod(i+j,2) eq 1 then 1
You can play around with the mod function to get a satisfactory effect. Maybe even regrid to a finer grid to alter the density.
On 23/04/14 19:31, Hussen Seid wrote: