skip (expr, skipx, skipy)
Sets alternating values of expr to the missing
data value. This function is used while displaying wind
arrows or barbs to thin the number of arrows or
barbs.
expr A valid grid expression skipx Skip factor in the X direction skipy Skip factor in the Y direction
skip function on
both the U and V wind components; it is sufficient to populate only one
component with missing data values to suppress the plotting of the wind
arrow or barb.
d skip(u,2,2);v
d skip(u,5,1);v
*
* This function does a d skip(ugrd,n);v
* where n is automatically set to an appropriate value
*
* usage: d_uv ugrd vgrd
*
* v1.1 w. ebisuzaki
* v1.2 4/6/98 revised empirical formula for skip
*
function duv(arg)
u = subwrd(arg,1)
v = subwrd(arg,2)
* get lat/lon info
'query dims'
lons = sublin(result,2)
lats = sublin(result,3)
dx = subwrd(lons,13) - subwrd(lons,11)
dy = subwrd(lats,13) - subwrd(lats,11)
* Determine skip factor
dn = dx
if (dy > dx) ; dn = dy ; endif
skip = dn / 50 + 0.5
if (skip < 1) ; skip=1 ; endif
* Display the plot
'd skip('u','skip');'v