R help - Jan 2011 - Help with IF operator

Hi,

I am with a problem on how to do a comparison of values. My script is as
follows:

repeat{
cat("How many teams to use? (to end write 0) ")
nro<-scan(n=1)
if(nro==0)break
cat("write the", nro, "teams names \n")
teams<-readLines(n=nro)
if (teams[1]==teams[2)next 
else print(teams)
}

On this example I only compare teams 1 name with teams 2 name, and if they
are the same the scrip starts again. If I had 10 teams how could I make it
compare the "nro" number of teams names in order to check if the same
name
has been written more then once? The idea is, if the same name is written
more then once it should give an error and start the scrip again by asking
the teams names again.

Two more things: With the next function the script stats from top, I mean
starts by asking the number of teams to use. Can I make it that it goes
directly to asking teams names?
And when it checks anc find out that a certain name has been written twice
can it produce a message warning that this error happened before asking the
teams names again?

Many thanks

Regards,
A.Dias.
-- 
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Several possibilities:

if (length(teams)!=length(unique(teams)) stop("Some teams are
duplicated")

or

if (max(table(teams))>1) stop("Some teams are duplicated")

I'm sure there are others, too.



On Thu, Jan 6, 2011 at 12:21 PM, ADias <diasandre at gmail.com>
wrote:
>
> Hi,
>
> I am with a problem on how to do a comparison of values. My script is as
> follows:
>
> repeat{
> cat("How many teams to use? (to end write 0) ")
> nro<-scan(n=1)
> if(nro==0)break
> cat("write the", nro, "teams names \n")
> teams<-readLines(n=nro)
> if (teams[1]==teams[2)next
> else print(teams)
> }
>
> On this example I only compare teams 1 name with teams 2 name, and if they
> are the same the scrip starts again. If I had 10 teams how could I make it
> compare the "nro" number of teams names in order to check if the
same name
> has been written more then once? The idea is, if the same name is written
> more then once it should give an error and start the scrip again by asking
> the teams names again.
>
> Two more things: With the next function the script stats from top, I mean
> starts by asking the number of teams to use. Can I make it that it goes
> directly to asking teams names?
> And when it checks anc find out that a certain name has been written twice
> can it produce a message warning that this error happened before asking the
> teams names again?
>
> Many thanks
>
> Regards,
> A.Dias.
> --
> View this message in context:
http://r.789695.n4.nabble.com/Help-with-IF-operator-tp3178129p3178129.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>

On Thu, Jan 06, 2011 at 12:21:33PM -0800, ADias wrote:
> 
> Hi,
> 
> I am with a problem on how to do a comparison of values. My script is as
> follows:
> 
> repeat{
> cat("How many teams to use? (to end write 0) ")
> nro<-scan(n=1)
> if(nro==0)break
> cat("write the", nro, "teams names \n")
> teams<-readLines(n=nro)
> if (teams[1]==teams[2)next 
> else print(teams)
> }
> 
> On this example I only compare teams 1 name with teams 2 name, and if they
> are the same the scrip starts again. If I had 10 teams how could I make it
> compare the "nro" number of teams names in order to check if the
same name
> has been written more then once? The idea is, if the same name is written
> more then once it should give an error and start the scrip again by asking
> the teams names again.
> 
> Two more things: With the next function the script stats from top, I mean
> starts by asking the number of teams to use. Can I make it that it goes
> directly to asking teams names?
Consider also using readline(), which reads a single line, and
%in% operator to compare the new name to the previous ones
immediately. 

  nro <- as.numeric(readline("no of teams "))
  teams <- rep(NA, times=nro)
  for (i in seq(length=nro)) {
      repeat {
          current <- readline(paste("team", i, ""))
          if (current %in% teams) {
              cat("error - repeated name\n")
          } else {
              break
          }
      }
      teams[i] <- current
  }

Petr Savicky.