On 28.04.2012 14:47, Sarah Goslee wrote:
> We really can't help you with your assignment. You might consider
> ??unique
> though, since you've already resolved to look for functions related to identifying unique entries.
>
> Sarah
>
> On Apr 28, 2012, at 8:11 AM, petermec <petermec@buffalo.edu> wrote:
>
>> Hi everyone, 
>>
>> I am somewhat new to R and I am trying to write a permutation function such
>> that it inputs a character vector and from an arbitrary length "n" which is
>> the length of the combinations for the character vector. I know there are R
>> packages for permutation but this is for an assignment.
>>
>> So far this is what I have:
>>
>> alphabet = c("a","b","c","d")
>> spot = c()
>> permute = function(alphabet,n){
>> for (i in 1:factorial(length(alphabet))){
>>    perm = sample(alphabet, replace=F, size=n)
>>    spot = rbind(spot, perm, deparse.level=2)
>> }
>> print(spot)
>> }
>>
>> This function works but it has some flaws for what I need. I would like the
>> print output to have the rownames as the combination of the characters for
>> each row (ie aa for "a" "a"). Also, this code is producing duplicate
>> combinations whereas I only want an output of unique combinations.
>>
>> To address the rownames problem I have, I have been trying to meddle around
>> with creating a dataframe from rbind with something like:
>> data2 = data.frame(spot, check.names=TRUE) 
>>
>> I was thinking something along the lines of this to remove duplicates:
>> or something like make.unique(spot)
>> or make.names(spot, unique=TRUE)
>>
>> Neither of these have been working for me. Could someone help point me in
>> the right direction?
>>
>> Much appreciated.
>>
>>
>> --
>> View this message in context: http://r.789695.n4.nabble.com/Writing-a-Permutation-Function-tp4594621p4594621.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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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.
> ______________________________________________
> R-help@r-project.org mailing list
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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.
Hi,

Rownames can be assigned by using rownames(dataframe) <- c("Row1",
"Row2", etc.)
The Wikipedia article about 'Permutation' holds some commonly used
Algoritms, perhaps you can find some inspiration there?

Good luck!

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