Re: [R] matrix not working

From: Dat Mai <dat.d.mai_at_gmail.com>
Date: Thu, 26 May 2011 19:39:56 +0000

When I use the as.matrix, the data.frame does turn into a matrix, but I cannot change the dimensions of the matrix. I'd still want it to have that pseudo cartesian format (e.g. [a1,b1], [a2,b2])

On Thu, May 26, 2011 at 6:58 PM, David Winsemius <dwinsemius_at_comcast.net>wrote:

>
> On May 26, 2011, at 1:53 PM, Andy Zhu wrote:
>
> Dat:
>>
>> 1. you can use as.matrix to convert data.frame to matrix;
>> 2. it is likely that the internal representation of your data.frame may
>> not be numerical value; matrix can only take on numeric.
>>
>>
> Not true. Can be any single mode, including "character", "list", and
> "logical".
>
> --
> david.
>
>
>
>>
>> --- On Thu, 5/26/11, Dat Mai <dat.d.mai_at_gmail.com> wrote:
>>
>> From: Dat Mai <dat.d.mai_at_gmail.com>
>> Subject: [R] matrix not working
>> To: r-help_at_r-project.org
>> Date: Thursday, May 26, 2011, 12:24 PM
>>
>> Hello All,
>>
>> I'm trying to create a matrix from a dataframe (let's call it df):
>> ......a......b.....c.....d
>> a inputs output
>> b inputs output
>> c inputs output
>> d inputs output
>> e inputs output
>>
>> The inputs are represented by columns a and b
>> The outputs are represented by columns c and d, but the only outputs are
>> those from column d
>> - some values from column d are NA
>> - column d was created with the code:
>>
>> df$d=rank(df$c, na.last="keep")
>>
>> #----------R Code---------#
>> item=unique(df$a)
>> n=length(list)
>>
>> r=matrix(data=NA,nrow=n, ncol=n, dimnames=list(PRR1=item, PRR2=item))
>>
>> for(j in 2:ln)
>> {
>> for(i in 1:(j-1))
>> {
>> input1=rownames(r)[i]
>> input2=colnames(r)[j]
>>
>> q=df[(df$a==input1 & df$b==input2), "d"]
>>
>> if(length(q)==0)
>> {
>> q=df[(df$a==input2 & df$b==input1), "d"]
>> }
>>
>> if(length(q)==0)
>> {
>> q=NA
>> }
>>
>> r[j,i]=q
>> r[i,j]=q
>> r[j,j]=q
>> }
>> }
>>
>> The result is a matrix with the appropriate dimensions, but everything is
>> filled with NA instead of the rankings of the various combinations. I'd
>> like
>> for the matrix to be filled with the ranking values--what have I done
>> wrong?
>> --
>> Best,
>> Dat Mai
>> PhD Rotation Student
>> Albert Einstein College of Medicine
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>
> David Winsemius, MD
> West Hartford, CT
>
>

-- 
Best,
Dat Mai
PhD Rotation Student
Albert Einstein College of Medicine

	[[alternative HTML version deleted]]

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Received on Thu 26 May 2011 - 19:41:58 GMT

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