[R] Plotting only masked part of data

[Dimitris Rizopoulos]

a simple approach is to use NAs, i.e.,

x <- seq(0,4*pi,by=0.1)
y <- sin(x)
##########
x. <- x; x.[!abs(y) < 0.5] <- NA
y. <- y; y.[!abs(y) < 0.5] <- NA

plot(x., y., type="l")


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat
     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Joakim Hove" <hove at ift.uib.no>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, January 25, 2005 2:57 PM
Subject: [R] Plotting only masked part of data


>
> Hello,
>
> I have x and y data to plot (synthetic example):
>
>  x <- seq(0,4*pi,by=0.1)
>  y <- sin(x)
>
> I then want to plot (x,y) in those points where abs(y) is smaller 
> than
> 0.5. As a first approximation
>
>  plot(x[abs(y) < 0.5],y[abs(y) < 0.5])
>
> is quite close - however I want to plot with lines, i.e. type="l", 
> and
> then I get solid lines connecting the endpoint of one "active" 
> region
> to the start of the next active region, I would prefer to get rid of
> those.
>
> Lineart:
> -------
>
>   _____               ____
>  / (1) \             / (3)\
> /       \           /      \
> /         \         /        \
>           \       /          \
>            \_____/
>              (2)
>
>
> The problem is the horisontal lines shown as (1), (2) and (3) in the
> schematic figure above, I would like to get rid of those,
> i.e. retaining only four disconnected segments. I have started on a
> programming based solution, plotting one piece at a time, but it is
> *very* ugly!
>
> Is there a simple general solution to my problem?
>
>
>
> Regards
>
> Joakim Hove
>
> -- 
> Joakim Hove
> hove AT ift uib no
> Tlf: +47 (55 5)8 27 90
> Fax: +47 (55 5)8 94 40
> http://www.ift.uib.no/~hove/
>
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