[R] Lines for plot (Sweave)

Doran, Harold HDoran at air.org
Fri Jul 1 19:57:50 CEST 2005

Fabulous, it works great. I didn't know about approx().

Thank you 

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: Friday, July 01, 2005 1:54 PM
To: Doran, Harold
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Lines for plot (Sweave)

On 7/1/05, Doran, Harold <HDoran at air.org> wrote:
> Dear List:
> I am generating a series of plots iteratively using Sweave. In short, 
> a dataframe is subsetted row by row and variable graphics are created 
> conditional on the data in each row. In this particular case, this 
> code ends up generating 17,000 individual plots.
> In some cases, all student data (this is working with student 
> achievement data) are available and my code below works very well in 
> the sense that a line connects all points. However, in some cases 
> there are missing data and I need to modify my code so that lines are 
> connected through all points even when data are missing.
> Here is a snip of relevant code. In the actual program, the data in 
> stu.vector and avg.vector are obtained from the dataframe as the 
> programs loops through each row.
> stu.vector<-c(2500, 2510,   NA , 2600)
> avg.vector<-c(2635, 2589, 2628, 2685)
> x <- c(0,1,2,3)
> graph.min <- min(stu.vector,avg.vector ,na.rm=TRUE)-150 graph.max <- 
> max(stu.vector,avg.vector ,na.rm=TRUE)+150 plot(x, stu.vector, 
> ylim=c(graph.min,graph.max),  xlab=" ", ylab="Scaled Score", xaxt='n',

> pch=2, col='blue', main="Math Growth Rate") points(x, avg.vector, 
> pch=1, col='red') lines(x, stu.vector, lty=1, col='blue') lines(x, 
> avg.vector, lty=3, col='red')
> If the NA did not exist in the object stu.vector then all points would

> be connected with lines. However, in some cases data are missing and I

> need to connect the data in stu.vector with lines. So in this case, 
> the line would connect points 1 and 2, and then 2 and 4 even though 
> point 3 is missing.

Replace the first lines statement with:

lines(approx(x, stu.vector), lty=1, col='blue')

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