Converting a data frame with values into a matrix/

The way that you have set up the data.frame is
rather
unusual. It makes NES a factor which I suspect you
don't want. Do str(xx) to see what I mean

Here is a way that I think does what you want but
with
the data.frame constructed in a different manner. 
Again do str(aa) to see the difference

aa <- data.frame(Name=c( "Mike" ,"Carl", "Gene",
"James","Dough"),
         Class=c(  "A",  "A",  "C",  "A",  "B"),
         NES=c( 0.01, 0.2, 0.3, -0.3, 0) )  
aa
         
library(reshape)
mm  <- melt(aa, id=c("Name", "Class"))
mm1  <- cast(mm, Class~Name)

aba <- mm1[,2:6]
aba[is.na(aba)] <- 1

final <- data.frame(mm1$Class, aba)
names(final) <- names(mm1) 
final

===================================================

--- Srinivas Iyyer <srini_iyyer_bio at yahoo.com>
wrote:

Dear Group, 
I have a data frame like the following:


x <- c("Mike","A",0.01)
x1 <- c("Carl","A",0.2)
x2 <- c("Gene","C",0.3)
x3 <- c("James","A",-0.3)
x4 <- c("Dough","B",0)
xx <- rbind(x,x1,x2,x3,x4)
colnames(xx)<-c("Name","Class","NES")
xx <-as.data.frame(xx)

xx

    Name Class  NES
x   Mike     A 0.01
x1  Carl     A  0.2
x2  Gene     C  0.3
x3 James     A -0.3
x4 Dough     B    0


Now I want to create a matrix with unique xx$Name

on

columns and unique xx$Class as rows.  I want to

fill

my choice of values (in this case 1) if data point
not
available. 


xy <-

colnames(xy)<-unique(xx[,1])
rownames(xy)<-unique(xx$Class)

xy

  Mike Carl Gene James Dough
A    1    1    1     1     1
C    1    1    1     1     1
B    1    1    1     1     1





I would love to have :

  Mike Carl Gene James Dough
A    0.01    0.2    1     -0.3     1
C    1    1    1     0.3     1
B    1    1    1     1    0




If I am not wrong this is called contigency or
frequeny table. 

I tried xtabs on this.  

z <- xtabs(NES ~ Name+Class,data=xx)

Error in Summary.factor(4L, na.rm = FALSE) : 
  sum not meaningful for factors


I tried on other data frames, it worked. BUT the
problem is it gives me 0.0000 even a value is not
available for that row and column.  So if I have
data
-0.00 it is considered 0. 

I tried. drop.unused.levels = T, I did not get

what

I
want. I want all row.col values not available to

be

1.


Is there any other trick where I map by row and
column
names instead of using advanced xtabs. 

thanks
Srini