
On Aug 23, 2009, at 10:51 PM, Steven Kang wrote:

> David, apreciate for your help.
>
> However, the result is not what I was expecting.
>
> Following on from your code, for example say the input is:
>
>    a <- data.frame(x=rep(1:4,2), y=rep(4:7,2), xx=rep(8:11,2),  
> xxx=rep(12:15,1))
>
>           x y xx xxx
>         1 1 4  8  12
>         2 2 5  9  13
>         3 3 6 10 14
>         4 4 7 11 15
>         5 1 4  8  12
>         6 2 5  9  13
>         7 3 6 10  14
>         8 4 7 11  15
>
> Using the following "subset" function:
>
>    sub.a <- subset(a, xx == 8)
>
> results in:
>
>           x y xx xxx
>        1 1 4  8  12
>        5 1 4  8  12
>
> Now, I would like to assign the value of subsetted argument (i.e 8  
> in this case)  to be able to use repetitively with other values.
> For example,
>
>    sub.a.8 <- sum(sub.a$xxx)     to get sum of xxx (=24) satisfying  
> the criteria where xx = 8
>
>    sub.a.9 <- sum(sub.a$xxx)     to get sum of xxx (=26) satisfying  
> the criteria where xx == 9
>    sub.a.10 <- sum(sub.a$xxx)   to get sum of xxx (=28) satisfying  
> the criteria where xx == 10 etc

Or perhaps even more programmatically:

 > for (zz in unique(a$xx) ) assign( paste("sub.a", zz, sep="."),  
sum(subset(a, xx==zz)$xxx) )

>
> Please enlighten my problem.
>
> thanks
>
>
>
>
> On Mon, Aug 24, 2009 at 12:19 PM, David Winsemius <dwinsemius@comcast.net 
> > wrote:
>
> On Aug 23, 2009, at 10:12 PM, David Winsemius wrote:
>
>
> On Aug 23, 2009, at 9:56 PM, Steven Kang wrote:
>
> Dear R users,
>
> I am using "subset" function to filter out specific conditions and  
> would
> like to use the value of subsetted argument as a name of an object.
>
> Specifically, from the following statement:
>
>   a <- subset(dat, dat$x == "A" & dat$xx == 1 & dat$xxx == "AB" & dat 
> $y
> == "B" & dat$yy == 2)
> I would to assign the value of the 3rd subset argument (i.e. "AB")  
> as an
> object's name such as:
>
>   a.AB <- sum(a$z)
>
> Sounds like you need to read FAQ 7.21:
>
> http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-can-I-turn-a-string-into-a-variable_003f
>
> Perhaps, ... lightly tested, of course, because no reproducible data  
> provided:
>
> assign( paste("a.",  sum(a$z), sep=""),
>       subset(dat,x == "A" & xx == 1 & xxx == "AB" &  y== "B" & yy ==  
> 2)   )
>
> # you do not need the "dat$"'s in the subset.
>
> > a <- data.frame(x=1:4, y=4:7, xx=8:11, xxx=12:15)
> > a
>  x y xx xxx
> 1 1 4  8  12
> 2 2 5  9  13
> 3 3 6 10  14
> 4 4 7 11  15
>
> Arrgh. Trimmed out the code:
>
> assign( paste("a.",  sum(a$x), sep=""),
>         subset(a,x == 1 & xx == 8 )   )
>
>
>
> > a.10
>  x y xx xxx
> 1 1 4  8  12
> -- 
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT


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