Re: [S] Transforming continuous variables

Berwin Turlach (berwin.turlach@anu.edu.au)
Mon, 27 Apr 1998 18:02:26 +1000


>>>>> "PS" == Paul Schwarz <Paul.Schwarz@cornell.edu> writes:

PS> [...] ifelse( x[ x >= 0 & x <= 90 ], 90-x, ifelse( x[ x > 90 & x
PS> <= 180 ], -(x-90), ... ), but that hasn't worked.
Hmmmh, I am not sure what the x[...] does around the conditional. The
basic idea works just fine with me:

> z <- (0:(360*5))/5
> y <- ifelse(z<=90,90-z,ifelse(z<=180,-(z-90),z-270))
> plot(z,y)

Of course,

> x <- abs(z-180)-90
> plot(z,x)

Is perhaps much clearer. And it gives the correct answer too :-)

> max(abs(x-y))
[1] 1.421085e-14

Cheers,

Berwin

=============================== Full address ================================

Berwin A Turlach
Centre for Mathematics and its Applications Tel.: +61 (2) 6249 0706 (Secr.)
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The Australian National University FAX : +61 (2) 6249 5549
Canberra ACT 0200 e-mail: berwin.turlach@anu.edu.au
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