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Re: [ferret_users] Cross-hatching in pyeffert

Hi Hussen,

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"

First method:

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
shade masked_corr

Second method:
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

shade corr
shade/ov/nolab/pal=black mask

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:
Dear ferret/pyferret users,

I installed pyferret to take advantage of its enhancements(improved graphics and new statistical functions), unfortunately fill/shade+patterns are not yet supported by pyferret. Instead I was trying to use cross-hatching, but not succeeded. 
So I'm wondering how to produce filled/shade colour figures with cross-hatching?

To make it clear:
I have two files; one with correlation and the other with significant correlation values. what I want to do is to overlay the significant correlations using cross-hatching.


Hussen Seid Endris
Climate System Analysis Group
Department of Environmental and Geographical Science
University of Cape Town
Private Bag Rondebosch, 7701
Tel:(+27) (0)74 222 4357

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