[R-sig-Geo] Lightning density map

[Adrian Antonescu]

Hi,

Two weeks ago I have asked a question regarding the use of R for plotting lightning density maps. Thanks to you answers I was able to go one step further.
Attached is the .R script and a sample of the data. The script is counting the number of lightning strikes in hexagons, and then is plotting the hexagons over Europe.
To obtain the lightning density I need the area of the hexagons. Could you please help me on how to calculate the area of the hexagons? Also, how can I obtain the
number of days with lightning  in each hexagons?

Thank you very much.

Cheers,
Bogdan
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