# [R] strange behavior of my function

Bill.Venables at csiro.au Bill.Venables at csiro.au
Wed Apr 2 07:24:16 CEST 2008

There are simpler looking ways of doing this.  Here are two

convert.to.trinom3 <- function(data, z1, z2)
ifelse(data < z1, 0, ifelse(data < z2, 1, 2))

convert.to.trinom3 <- function(data, z1, z2)
cut(data, c(-Inf, z1, z2, Inf), labels = FALSE) - 1

The second neatly generalizes to the case of more than three bins.

Bill Venables
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-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of ronggui
Sent: Wednesday, 2 April 2008 2:03 AM
To: Kyeongmi Cheon
Cc: R help mailing list
Subject: Re: [R] strange behavior of my function

You should write the function in this way, I think.

convert.to.trinom3=function(data, z1, z2){
ans <- data
ans[data<z1]=0
ans[z1<=data & data<z2]=1
ans[data>=z2]=2
ans
}

On Tue, Apr 1, 2008 at 11:54 PM, Kyeongmi Cheon <katie.cheon at gmail.com>
wrote:
> Hello,
>  I wrote a program to convert normal distribution  to trinomial
>  distribution (three levels=0,1,2). But the first function I wrote
>  (convert.to.trinom1) converts everything to 2. When I changed it
>  slightly (convert.to.trinom2), it works correctly (ie. converts to
>  0,1, or 2). I cannot figure out why it happens. I even restarted R
and
>  tried again and the same thing happened over and over. I use R 2.6.0
>  in Windows Vista. Can anyone help me with this? Thank you.
>  Kyeongmi
>
>
>
>  norm1=rnorm(20)
>  norm1
>
>  z1=-1.2212272
>  z2=-0.6744898
>  convert.to.trinom1=function(data, z1, z2){
>     data[data<z1]=0
>     data[z1<=data & data<z2]=1
>     data[data>=z2]=2
>     data
>  }
>  trinom1=convert.to.trinom1(norm1,z1, z2)
>  trinom1
>
>  convert.to.trinom2=function(data, z1, z2){
>     data[data>=z2]=2
>     data[data<z1]=0
>     data[z1<=data & data<z2]=1
>     data
>  }
>  trinom2=convert.to.trinom2(norm1,z1, z2)
>  trinom2
>
>  ______________________________________________
>  R-help at r-project.org mailing list
>  https://stat.ethz.ch/mailman/listinfo/r-help
>  PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>  and provide commented, minimal, self-contained, reproducible code.
>

--
HUANG Ronggui, Wincent

Bachelor of Social Work, Fudan University, China

Master of sociology, Fudan University, China

Ph.D. Candidate, CityU of HK,
http://www.cityu.edu.hk/sa/psa_web2006/students/rdegree/huangronggui.htm
l

______________________________________________
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.

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