[gradsusr] Find nearest gridpoint to given location that has data available

[Jonas Kaufmann]

Hello,

I have a set of wave data where there is only valid data over sea -
gridpoints over land have undefined values. I know I can get a visual
representation of all available gridpoints using set gxout grid or
grfill. I also know that if I simply use set lat and set lon, I should
receive data from the nearest gridpoint.

However, when I set lat and lon to a location at the coastline I may
also get data from a gridpoint with undefined values (e.g. the nearest
gridpoint would then be over land). Is there a way that I can query
the nearest gridpoint to a given location where there is data
available?

Thank you for your answer!

Best regards,
Jonas Kaufmann