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vector or list surrounding_points_indexes ( fieldset,list[,string] ) Anchor surrounding_points_indexes surrounding_points_indexes
vector or list surrounding_points_indexes ( fieldset,number,number[,string] )
vector or list surrounding_points_indexes ( fieldset,vector,vector[,string] )
Returns the indexes of the four gridpoints surrounding the given location, ordered by increasing distance from the target point. If a list is given, it must contain two numbers - latitude and longitude. If two numbers are given, the first is the latitude, the second the longitude. The field must be a gridded field. If the fieldset has only one field, a single vector of indexes is returned; otherwise a list of vectors is returned. In the case where the field is a reduced Gaussian grid and the input location is at the North or South pole, beyond the most extreme row of points, there will be a 'circle' of surrounding points, and all of these indexes are returned.
For batch processing of multiple locations, two vectors can be given, the first is a vector of latitudes, the second the longitudes; this can be much more efficient than multiple calls with a single location each. If the fieldset has only one field, a single vector is returned; otherwise a list of vectors is returned.
By default, if any of the surrounding points are missing, the function will return nil
. To prevent this, and to return all the points regardless, add the option 'all'
as the last parameter of the function call.
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