converting values of a dataframe to numeric (where possible)

When I do as.matrix I loose those columns that I specified as row headers
during cast.
Maybe its because of this:
"When coercing a vector, it produces a one-column matrix, and promotes the
names (if any) of the vector to the rownames of the matrix."
but I cant figure out what does this mean or what to do to make it work.

Thanks for the help.
B.

df <- data.frame(
  entityID=c(10,10,10,12,12,12),
  attributeID=c("attr1","attr2","attr3","attr1","attr2","attr3"),
  value=c(10,11,12,"aa",21,22)
)
x<-cast(df,entityID ~ attributeID)
x
as.matrix(x)



jholtman wrote:

Try this as a solution:

df <- data.frame(a=letters[15:17], b=c("21","NA","23"), c=10:12,
d=15:17)
# convert to numeric
x <- as.matrix(df)
mode(x) <- "numeric"

Warning message:
In eval(expr, envir, enclos) : NAs introduced by coercion

cbind(df, RTot=rowSums(x, na.rm=TRUE))

  a  b  c  d RTot
1 o 21 10 15   46
2 p NA 11 16   27
3 q 23 12 17   52

On Tue, Sep 2, 2008 at 5:50 PM, Ralikwen <Balazs.Klein at gmail.com> wrote:

Hi,
I am new to R.
I have a dataframe with many columns some of which contain genuine
strings
some numerical values as strings. The dataframe is created by cast so I
have
no control over the resulting data type.
I want to attach columns as aggregates of other columns to the
dataframe.
Here is the solution that I came up with (after a lot of struggle):

castNum <- function(n) {
   x<-as.numeric(as.character(n))
   if (is.na(x)){
     return(n)
   }else{
     return(x)
   }
}
df <- data.frame(a=letters[15:17], b=c("21","NA","23"), c=10:12,
d=15:17)
cbind(df,RTot=rowSums(as.data.frame(lapply(df, function(x)
castNum(x)))[2:4],na.rm=TRUE))

This works, but is full of warnings and looks extremely ugly.
Could you direct me how to achieve the same result in a more elegant
way?

Thx.
Bal?zs



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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?