[ -R] Summary converting among modes

Thank you very much for the response.
The way to get rid of those pesky characters is to first convert to
character (from the default factor), THEN convert to numeric. I had tried
using as.is= in read.table, but I used it incorrectly (as.is=TRUE instead of
as.is= <vector of col indices>).

as.numeric( as.character( vect.dat ) )
NOT simply    as.numeric(vect.dat)

I used as.is= incorrectly. I simply used as.is=TRUE, and did not specify
----- Original Message -----
From: "Thomas Lumley" <tlumley at u.washington.edu>
To: "Martin Henry H. Stevens" <hstevens at muohio.edu>
Cc: <r-help at stat.math.ethz.ch>
Sent: Friday, July 27, 2001 1:47 PM
Subject: Re: [R] converting among modes

On Fri, 27 Jul 2001, Martin Henry H. Stevens wrote:

Windows 2000, R 1.3.0

I have been given a data set (ASCII tab delimited) in which many

variables

that are supposed to be numeric actually contain characters. I would be
happy to have those character entries disappear and become NA.

When I use read.table and then attempt to convert these using

as.numeric(),

of course it doesn't work, and I get the ASCII? representation? maybe?

When

I use scan() and specify the data type (what=...), I get an error

message

saying that I have character data in the numeric variable.

If there are only a few different character strings causing problems you
can use the na.strings option of read.table().

Your data are actually read as *factors*, not as characters, and
as.numeric() gives the factor codes.  Converting factors to numeric is a
FAQ (7.13); use as.numeric(as.character(the.factor))


-thomas

Thomas Lumley Asst. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._