Re: [R] problem with if else statement

From: Petr PIKAL <petr.pikal_at_precheza.cz>
Date: Tue, 08 Jun 2010 13:01:52 +0200

Hi

r-help-bounces_at_r-project.org napsal dne 08.06.2010 11:46:17:

> Hi,
>
> You are using if/then/else which is a logical control statement and so
doesn't
> return a value, see
> ?if
> for details.
>
> You are probably looking for the ifelse function.

Or use possibility of easy conversion logical (T/F) to numeric (1/0)

rr.dia.2m - (med.hyper==1)*5

Regards
Petr

>
> Martyn
>
> -----Original Message-----
> From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org]
On
> Behalf Of Peter Lercher
> Sent: 08 June 2010 10:18
> To: r-help_at_r-project.org
> Subject: [R] problem with if else statement
>
> Dear colleagues,
>
> What did I not understand ?
>
> ->my intention
> I want to create a new variable:
> In plain language:
> If someone is taking anithypertensive treatment (med.hyper==1)
> table(med.hyper)
> med.hyper
> 0 1
> 472 97
> I want to subtract 5 mmHg (rr.dia.2m-5) from the measured diastolic
blood
> pressure (rr.dia.2m) if not treated - the value of the measured
diastolic
> blood pressure should remain the same
>
> ->my code (data frame is attached !)
> rr.dia2.corr<-if(med.hyper==1)
> {
> rr.dia.2m-5
> } else
> {
> rr.dia2.corr==rr.dia.2m
> }
>
> R warning
> Warnmeldung:
> In if (med.hyper == 1) { :
> Bedingung hat Lšnge > 1 und nur das erste Element wird benutzt "Only
first
> condition is use"
> which you can see from the result (simply 5 mm was subtracted and the
second
> condition was taken into account)
>
> > describe(rr.dia.2m)
> rr.dia.2m
> n missing unique Mean .05 .10 .25 .50
> .75 .90 .95
> 546 26 110 85.32 67.00 71.50 77.62 84.50
> 92.00 99.25 105.00
>
> lowest : 45.0 57.0 60.0 61.0 62.0, highest: 127.5 128.5 129.5 142.5
> 146.5
> > describe(rr.dia2.corr)
> rr.dia2.corr
> n missing unique Mean .05 .10 .25 .50
> .75 .90 .95
> 546 26 110 80.32 62.00 66.50 72.62 79.50
> 87.00 94.25 100.00
>
> lowest : 40.0 52.0 55.0 56.0 57.0, highest: 122.5 123.5 124.5 137.5
> 141.5
> --------------------
> OS windows
> R version 2.10.1 (2009-12-14)
> attached R modules: design+hmisc
> ------------------
> Thank you so much
>
> Peter
>
>
>
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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. Received on Tue 08 Jun 2010 - 11:06:16 GMT

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