Dear all I want to put zeros and ones in matrix I have if the values are over a threshold For that I use: origBoolmap<- (origmap >thresh ) origBoolmap[thresh < origmap] <- 1 origBoolmap[thresh >= origmap] <- 0 Could you please tell me if the first line out of the three is useless? I have checked and seems taht I take the same results. Best Regards Alex