[R] plotting a point graph with data in X-axis

[Adaikalavan Ramasamy]

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
> 
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