R understands only numerical and Date class values for axis. So either
a) plot them using the sequence 1, ..., 32 and then explicitly label them. Here is an example: n <- length(year.month) plot( 1:n, freq, xaxt="n") mtext( text=year.month, side=1, at=1:n, las=2 ) b) or create the dates in Date format. This option is preferable if the dates were varying unequally. x <- seq( as.Date("2000-05-01"), as.Date("2002-12-01"), by="1 month" ) plot(x, simulation$freq) BTW, you could also have created year.month via paste( rep( 2000:2002, c(8,12,12) ), formatC( c(5:12,1:12,1:12), width=2, flag="0" ) , sep="_" ) Regards, Adai Milton Cezar Ribeiro wrote: > Dear all, > > I have two data frame, on with a complete list of my field survey with > frequency data of a sample species. This data frame looks like: > > > simulation<-data.frame(cbind(my.year=c(rep(2000,8),rep(2001,12),rep(2002,12)),my.month=c(5:12,1:12,1:12))) > simulation$year.month<-paste(simulation$my.year,"_",ifelse(simulation$my.month>=10,simulation$my.month,paste("0",simulation$my.month,sep="")),sep="") > simulation$freq<-sample(1:40,32) > attach(simulation) > plot(year.month, freq) > > As you can see, I have a collumn with the year and month of my samples, and a > freq variable with simulated data. I would like to plot this data but when I > try to use the plot showed above, I get a error message. > > After bypass this problem, I would like add points in my graph with simulated > data for only a random number of survey month, but I need that the full range > of surveys be kept on the X-axis. Just to simulate a sample I am using: > > simulation.sample<-simulation[sample(1:length(year.month),8, replace=F),] > simulation.sample$freq<-sample(1:40,8) > > Any ideas? > > Kind regards > > Miltinho > > __________________________________________________ > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.