[R] Creating a data.frame

[Chuck Cleland]

On 2/13/2008 5:17 PM, Joe Trubisz wrote:
> OK...newbie question here.
> Either I'm reading the docs wrong, or I'm totally confused.
> 
> Given the following:
> 
> x<-c("aaa","bbb","ccc")
> y<-rep(0,3)
> z<-rep(0,3)
> 
> is.character(x)
> [1] TRUE
> 
> is.numeric(y)
> [1] TRUE
> 
> Now...I want to create a data frame, but keep the data types.
> In reading the docs, I assume you do it this way:
> 
> d<-data.frame(cbind(x=I(x),y=y,z=z)
> 
> But, when I do str(d), I get the following:
> 
> 'data.frame':	3 obs. of  3 variables:
>   $ x: Factor w/ 3 levels "aaa","bbb","ccc": 1 2 3
>   $ y: Factor w/ 1 level "0": 1 1 1
>   $ z: Factor w/ 1 level "0": 1 1 1
> 
> I thought the I() prevents character from becoming factors, right?
> Secondly, how do I force y and z in the data frame to become numeric?

   Don't use cbind() inside of data.frame().  Using cbind() coerces the 
variables into a matrix where all variables share a common type.  I 
think you want this:

d <- data.frame(x=I(x), y=y, z=z)

> Thanks in advance
> Joe
> 
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Chuck Cleland, Ph.D.
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