[R] Converting xy plot arguments into a point argument and fixed x-axis scaling
David Winsemius
dwinsemius at comcast.net
Sat Sep 20 21:55:18 CEST 2014
On Sep 19, 2014, at 1:55 PM, nebulo help wrote:
> Dear all,
>
> I have a data.frame xy which I am plotting like in the code below (provided is a small data sample with dummy data that should work).
>
> Is there a way how I could convert my xx and yy in the xy plot to a points command so that I could set type='n' and add points afterwards in order to control it better?
>
> In the end what I am also aiming for is a fixed x-axis range (e.g. from 1940 to 2014) and if values before 1940 are present the x axis should be automatic. The y axis should always be in the range of the values generated for each plot.
I would think the general strategy would be to call `plot` and axis (twice) just once and axis (twice) with the xlim, ylim, xlab and ylab set to your specifications and then within the loop, use `points`.
--
David.
>
> Thank you for your help!
>
> Kind regards,
> Kurt
>
> ###########################
>
> Here is my code with sample data:
>
> # read in sample data
> xy <- data.frame(NAME=c("NAME1","NAME1","NAME1","NAME2","NAME2","NAME2"),ID=c(87,87,87,199,199,199), X_START_YEAR=c(1984,1986,1984,1899,1909,1924),Y_START_VALUE=c(75,25,-90,-8,-55,-10),X_END_YEAR=c(1986,1994,1999,1909,1924,1927), Y_END_VALUE=c(20,50,-15,-70,-80,-100))
>
> # split data.frame into groups (defined by ID in this case)
> ind <- split(xy,xy$ID)
> # plot data by group
> for (x in ind){
> xx = unlist(x[,grep('X_',colnames(x))])
> yy = unlist(x[,grep('Y_',colnames(x))])
> fname <- paste0(x[1, 'ID'], '.png')
> png(fname, width=1679, height=1165, res=150)
> par(mar=c(6,8,6,5))
> plot(xx,
> yy,
> main=unique(x[,1]),
> xlab="Time [Years]",
> ylab="Value [m]")
> axis(1, at = seq(1000, 2050, 5), cex.axis=1, labels=FALSE, tcl=-0.3)
> axis(2, at = seq(-100000, 100000, 500), cex.axis=1, labels=FALSE, tcl=-0.3)
> x <- x[,-1]
> segments(x[,2],x[,3],x[,4],x[,5],lwd=2)
> dev.off()
> }
>
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David Winsemius
Alameda, CA, USA
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