Yes Roman, I want 3 columns : X =Long, Y=Lat and Frequency. Edzer, I will try library (sp). Thank you in advance Komine -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Number-of-duplicated-pixels-tp7133208p7133427.html Sent from the R-sig-geo mailing list archive at Nabble.com.