[R] matching identical row names

[John Fox]

Dear John,

You can use aggregate(), also described in my suggestion to Sirinivas:

> aggregate(Data[, 4:6], Data[1:3], sum)
  Prog Sub.Program Job V1 V2 V3
1    1       Alpha   A  3  4  5
2    2       Alpha   A  3  4  1
3    2       Alpha   B  2  3  1
4    2       Gamma   B  3  5  6

I hope this helps,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
-------------------------------- 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of John Kane
> Sent: Sunday, April 16, 2006 10:29 AM
> To: John Fox; Srinivas Iyyer
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] matching identical row names
> 
> Dear Dr. Fox
> Your reply to Sirinivas Iyyar was most helpful to me. I am 
> trying to collapse some categories of a data.frame in a similar way.  
> I have a data frame in the form below 
> 
> Prog     Sub.Program   Job  V1  V2  V3
>   1         Alpha               A     1   2   3
>   2         Alpha               B     2   3   1
>   2         Gamma            B     1   3   3
>   2         Alpha               A     3   4   1
>   2         Gamma            B     2   2   3
>   1         Alpha               A     2  2    2
>  
> What I want is to sum the values of VI, V2 and V3 and end up 
> with a new data.frame that would look like
>  
>    Prog    Subprog     Job   Sum(V1)  Sum(V2), Sum(V3)
>     1          Alpha        A        3            4              5
>     2          Alpha        A        3            4              1
>     2          Gamma     B         3            5               6
> 
> I thought that I could use by() to create a vector for each 
> of V1:V3 but I cannot see any way to capture the values.
> temp1 <- by(Data[,4] simply gives me the complete output.
> 
> An example of what I have done is
> -------------------------------------------------------------
> 
> Prog  <- 1, 2, 2, 2,2,1,    
> Sub.Program <-  c("Alpha", "Alpha", "Gamma", "Alpha", 
> "Gamma", "Alpha" )
> Job <- c("A",     "B",     "B",     "A",     "B",    "A")    
> V1 <- c(1,2, 1,3,2,2)
> V2 <-  c(2, 3, 3, 4, 2, 2)   
> V3 <-  c(3, 1 , 3, 1, 3,2 
> Mydata <- data.frame(cbind( Prog, Sub.Program, Job, V1, V2, V3)   
> 
> by(MyData[,4],list(Sub.Program=Sub.Program, Job=Job), sum)
> ----------------------------------------------------------------
>  
> I also get the expected <NA. for cells that do not exist. Is 
> there any way to set them to "0" in the operation?  
> 
>  
> 
> Any help would be greatly appreciated. 
> Thanks
> John
> 
> ----- Original Message ----
> From: John Fox <jfox at mcmaster.ca>
> To: Srinivas Iyyer <srini_iyyer_bio at yahoo.com>
> Cc: r-help at stat.math.ethz.ch
> Sent: Saturday, April 15, 2006 9:35:46 AM
> Subject: Re: [R] matching identical row names
> 
> Dear Srinivas,
> 
> Your data are likely in a data frame rather than a matrix 
> (since the columns are heterogeneous), and name is a 
> variable, not the row names of the data frame.
> 
> There are several ways to do what you want; one simple way, 
> assuming that the data are in a data frame named Data, is
> 
>  by(Data[,2:5], Data$name, mean)
> 
> If you want the result in the form of a matrix, then you could do
> 
>  aggregate(Data[,2:5], list(Data$name), mean)
> 
> I hope this helps,
>  John
> 
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> -------------------------------- 
> 
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch 
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Srinivas Iyyer
> > Sent: Friday, April 14, 2006 11:58 PM
> > To: r-help at stat.math.ethz.ch
> > Subject: [R] matching identical row names
> > 
> > dear group,
> >  
> > i have a sample matrix
> > name   v1   v2   v3   v4
> > cat   10    11   12   15
> > dog   3     12   10   14
> > cat   9     12   12   15
> > cat   5     12   10   11
> > dog   12    113  123  31
> > ...
> > 
> > 
> > since cat is repeated 3 times, I want a mean value for it. 
> > Like wise for every element of the name column. 
> > cat v1 = mean(c(10,9,5))
> > cat v3 = mean(c(11,12,13))
> > ..etc.
> > 
> > name v1   v2     v3   v4
> > cat  8   11.6   11.3  13.6
> > dog  7.5 62.5   66.5  22.5
> > 
> > could any one help me in solving this mystery. thank you.
> > 
> > ______________________________________________
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> 
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