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The second argument is a list of four numbers (lat/long coordinates) defining a geographical area - [North,West,South,East] . The function extracts all the geopoints that fall within the specified area.
geopoints find ( fieldset,number )
geopoints find ( fieldset,number,number )
A filtering function that returns a geopoints holding the grid points whose value is equal to the value of the first number. If a second number is given as the third argument it is a tolerance threshold and the geopoints will hold the grid points for which :
abs(data-value) <= threshold
geopoints geosort ( geopoints )
Returns a new geopoints variable that contains the input geopoints sorted geographically from North to South (and West to East in points with the same latitude value, then by height, with lowest numerical values first).
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