R help - Sep 2002 - Converting the columns of a data frame to numeric

Hello,

I have a data frame whose columns are factors with numeric levels and I 
want to convert the columns to numeric so that I can treat the data frame 
as a matrix.
I found a way of doing this but would like to know if there is an easier way.

My way is:

M <- matrix(ncol=ncol(df) , nrow=nrow(df) , as.numeric(as.matrix(df)))

where 'df' is the data frame.

I am wondering if there is a function, similar to as.numeric(), that 
converts each column of the matrix 'as.matrix(df)' to numeric.

Thanks
Daniel Mastropietro

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Daniel Mastropietro wrote:
> 
> Hello,
> 
> I have a data frame whose columns are factors with numeric levels and I
> want to convert the columns to numeric so that I can treat the data frame
> as a matrix.
> I found a way of doing this but would like to know if there is an easier
way.
> 
> My way is:
> 
> M <- matrix(ncol=ncol(df) , nrow=nrow(df) , as.numeric(as.matrix(df)))
> 
> where 'df' is the data frame.
> 
> I am wondering if there is a function, similar to as.numeric(), that
> converts each column of the matrix 'as.matrix(df)' to numeric.
In your case
  apply(df, 2, as.numeric)
should work (coercing each column to numeric and the data.frame to a
matrix). 
Since it operates on vectors and not on the whole object, this way is
less efficient than the way you mentioned above. 

If you import the data.frame, you might want to tell R that the column
should be treated as numeric.

Uwe Ligges
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>>>>> "Daniel" == Daniel Mastropietro <mastropi at
uwalumni.com>
>>>>>     on Sun, 01 Sep 2002 16:35:29 -0300 writes:
    Daniel> Hello, I have a data frame whose columns are factors
    Daniel> with numeric levels and I want to convert the
    Daniel> columns to numeric so that I can treat the data
    Daniel> frame as a matrix.  I found a way of doing this but
    Daniel> would like to know if there is an easier way.

    Daniel> My way is:

    Daniel> M <- matrix(ncol=ncol(df), nrow=nrow(df),
as.numeric(as.matrix(df)))

    Daniel> where 'df' is the data frame.

Would
	M <- data.matrix(df)

solve your problem?  I think it is intended to.
Martin
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