skip()

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

Usage Notes

1. It is not necessary to use the 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.

Examples

1. To display every other grid point in both the X and Y direction:
   d skip(u,2,2);v

2. To display every grid point in the Y direction, but every 5th grid point in the X direction:
   d skip(u,5,1);v

3. This example script "d_uv.gs" written by Wesley Ebisuzaki automatically sets the skip factor based on the plot dimensions.

   *
   * 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