R help - Jun 2007 - Got "Unexpected ELSE error"

Dear R-users,

I have a problem with the IF-ELSE syntax.
Please look at the folllowing code and tell me what's wrong:

a <- TRUE
if ( a )
{
        cat("TRUE","\n")
}
else
{
        cat("FALSE","\n")
}

If I try to execute with R I get:
     Error: syntax error, unexpected ELSE in "else"
The strange thing is either "cat" instructions are executed!!

My system is: Fedora Core 6 x86_64 + R 2.5.0 (rpm)

Thank you very much in advance!!!!

Regards,

-- Marco

Shiazy Fuzzy wrote:
> Dear R-users,
> 
> I have a problem with the IF-ELSE syntax.
> Please look at the folllowing code and tell me what's wrong:
> 
> a <- TRUE
> if ( a )
> {
>         cat("TRUE","\n")
> }
At this point, the expression above is complete and it ios evaluated if 
called interactively.
Then, the code below is invalid (there is nothing that starts with
"else").



> else
> {
>         cat("FALSE","\n")
> }

Instead, use:

a <- TRUE
if ( a )
{
         cat("TRUE","\n")
} else
{
         cat("FALSE","\n")
}


Uwe Ligges
> If I try to execute with R I get:
>      Error: syntax error, unexpected ELSE in "else"
> The strange thing is either "cat" instructions are executed!!
> 
> My system is: Fedora Core 6 x86_64 + R 2.5.0 (rpm)
> 
> Thank you very much in advance!!!!
> 
> Regards,
> 
> -- Marco
> 
> ______________________________________________
> R-help at stat.math.ethz.ch 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.

You need to put the else statement on the same line as the closing curly
bracket.

a <- TRUE
if ( a ){
        cat("TRUE","\n")
} else {
        cat("FALSE","\n")
}

Cheers,

Thierry

------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be
www.inbo.be 

Do not put your faith in what statistics say until you have carefully
considered what they do not say.  ~William W. Watt
A statistical analysis, properly conducted, is a delicate dissection of
uncertainties, a surgery of suppositions. ~M.J.Moroney

 
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces op stat.math.ethz.ch 
> [mailto:r-help-bounces op stat.math.ethz.ch] Namens Shiazy Fuzzy
> Verzonden: woensdag 20 juni 2007 11:41
> Aan: r-help op stat.math.ethz.ch
> Onderwerp: [R] Got "Unexpected ELSE error"
> 
> Dear R-users,
> 
> I have a problem with the IF-ELSE syntax.
> Please look at the folllowing code and tell me what's wrong:
> 
> a <- TRUE
> if ( a )
> {
>         cat("TRUE","\n")
> }
> else
> {
>         cat("FALSE","\n")
> }
> 
> If I try to execute with R I get:
>      Error: syntax error, unexpected ELSE in "else"
> The strange thing is either "cat" instructions are executed!!
> 
> My system is: Fedora Core 6 x86_64 + R 2.5.0 (rpm)
> 
> Thank you very much in advance!!!!
> 
> Regards,
> 
> -- Marco
> 
> ______________________________________________
> R-help op stat.math.ethz.ch 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.
>

the problem is that you start `else' on a new line; check the 
following two solutions:

if ( a ) {
    cat("TRUE", "\n")
} else {
    cat("FALSE", "\n")
}

# or

{
if ( a )
{
    cat("TRUE", "\n")
}
else
{
    cat("FALSE", "\n")
}
}


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/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm



----- Original Message ----- 
From: "Shiazy Fuzzy" <shiazy at gmail.com>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, June 20, 2007 11:41 AM
Subject: [R] Got "Unexpected ELSE error"

> Dear R-users,
>
> I have a problem with the IF-ELSE syntax.
> Please look at the folllowing code and tell me what's wrong:
>
> a <- TRUE
> if ( a )
> {
>        cat("TRUE","\n")
> }
> else
> {
>        cat("FALSE","\n")
> }
>
> If I try to execute with R I get:
>     Error: syntax error, unexpected ELSE in "else"
> The strange thing is either "cat" instructions are executed!!
>
> My system is: Fedora Core 6 x86_64 + R 2.5.0 (rpm)
>
> Thank you very much in advance!!!!
>
> Regards,
>
> -- Marco
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
> 

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

Shiazy Fuzzy wrote:
> Dear R-users,
>
> I have a problem with the IF-ELSE syntax.
> Please look at the folllowing code and tell me what's wrong:
>
> a <- TRUE
> if ( a )
> {
>         cat("TRUE","\n")
> }
> else
> {
>         cat("FALSE","\n")
> }
>
> If I try to execute with R I get:
>      Error: syntax error, unexpected ELSE in "else"
> The strange thing is either "cat" instructions are executed!!
>   
For some odd reason this is not actually a FAQ...

It is an anomaly of the R (and S) language (or maybe a necessary
consequence of its interactive usage) that it tries to complete parsing
of expressions as soon as possible, so 

2 + 2
+ 5

prints "4" and then "5", whereas

2 + 2 +
5

prints "9".  Similarly, when encountered on the command line,

if (foo) bar

will result in the value of bar if foo is TRUE and otherwise NULL. A
subsequent

else baz

will be interpreted as a new expression, which is invalid because it
starts with "else". To avoid this effect you can either move the
"else"
to the end of the previous line, or put braces around the whole if
construct. I.e.

if (foo) {
    bar
} else {
    baz
}

or

if (foo) bar else baz

or

{
    if (foo)
         bar
    else
         baz
}

should all work.

-- 
   O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907