On Aug 18, 2010, at 5:18 AM, Philip Wong wrote:
hello people,
I want to make a biased dice using the sample() function and print
out the
results after n number of runs, I've successfully generated the dice
using
the following command:
mydie2<-function(n=1000,y=NULL,...){
for(i in 1:n){
x<-sample(1:6,n,replace=TRUE,prob=c(1,1,2,3,2,1)/10)
x=runif(n)
if(x<=1/10){y[i]=1}
else if(x<=2/10){y[i]=2}
else if(x<=4/10){y[i]=3}
else if(x<=7/10){y[i]=4}
else if(x<=9/10){y[i]=5}
else{y[i]=6}
}
bar<-barplot(table(y))
table<-table(y)
return(list(bar,table))
}
mydie2()
but I also want to try to create the same dice stimulation using
ifelse()
When problems are posed with a requirement to use a particular
function, it makes me think there is a homework assignment underlying
the request, so I will offer a hint rather than making an effort at a
solution to your full problem. You can use nested ifelse's:
> set.seed(123); x=runif(20); y<- vector("numeric", length(x))
> y <- ifelse( x<=1/10, 1, ifelse( x <= 2/10, 2, ifelse (x <= 3/10 ,
3, 4)))
> x; y
[1] 0.28757752 0.78830514 0.40897692 0.88301740 0.94046728
0.04555650 0.52810549 0.89241904
[9] 0.55143501 0.45661474 0.95683335 0.45333416 0.67757064
0.57263340 0.10292468 0.89982497
[17] 0.24608773 0.04205953 0.32792072 0.95450365
[1] 3 4 4 4 4 1 4 4 4 4 4 4 4 4 2 4 3 1 4 4
statement, but all hell break loose when I attempt to use the
command below
(the barplot only shows the results to be 6), can anyone tell me
what went
wrong please:
mydie2<-function(n=1000,y=NULL,...){
for(i in 1:n){
x<-sample(1:6,n,replace=TRUE,prob=c(1,1,2,3,2,1)/10)
x=runif(n)
ifelse((x<=1/10),{y[i]<-1},
ifelse((x<=2/10),{y[i]<-2},
ifelse((x<=4/10),{y[i]<-3},
ifelse((x<=7/10),{y[i]<-4},
ifelse((x<=9/10),{y[i]<-5},{y[i]<-6})))))
}
bar<-barplot(table(y))
table<-table(y)
return(list(bar,table))
}
mydie2()
--
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West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
