R help - Feb 2009 - How to convert Charagter variables into numeric

I am importing a dataset in R where some of the variable are numerical and
some of them are character...but the problem is that R is treating 
numerical variables as character (I am using "is.character" to judge
the
type). Now the question is how can I convert these character variables into
numeric and also let me know about the other conversion like "numeric to
categorical","numeric to continuous" etc.Thank you.

Arup  
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You might want to try as.numeric(X), if you want to convert a factor then
you could use as.numeric(as.character(X)), where X is a "variable".

Karina





On Thu, 5 Feb 2009 22:50:38, <arup.pramanik27 at gmail.com> wrote:
> I am importing a dataset in R where some of the variable are numerical
and
> some of them are character...but the problem is that R is treating
> numerical variables as character (I am using "is.character" to
judge the
> type). Now the question is how can I convert these character variables
into
> numeric and also let me know about the other conversion like "numeric
to
> categorical","numeric to continuous" etc.Thank you.
>
> Arup
>
>
--

if you use read.table for the import, reading about the colClasses
parameter in ?read.table may help.

vQ

> On Thu, 5 Feb 2009 22:50:38, <arup.pramanik27 at gmail.com> wrote:
>
>   
>> I am importing a dataset in R where some of the variable are numerical
>>     
> and
>   
>> some of them are character...but the problem is that R is treating
>> numerical variables as character (I am using "is.character"
to judge the
>> type). Now the question is how can I convert these character variables
>>     
> into
>   
>> numeric and also let me know about the other conversion like
"numeric to
>> categorical","numeric to continuous" etc.Thank you.
>>
>> Arup
>>

Dear Arup,

It's very difficult to know what's going on without more information.
What
is the form of the data that you're importing and how are you reading the
data? I ask because the most common way of getting data into R is probably
via read.table(), which by default converts character data to factors but
reads numbers as numeric. If a "column" of input data has one or more
non-numeric entries (other than the default missing-data indicator NA), it
will be read as a factor, even if most entries in the column are numbers.

To answer your more general question, R has a number of "coercion"
functions
prefixed by "as." for changing data from one form to another: For
example,
if by "numeric to categorical" you mean numeric to a factor, then
as.factor() will do the trick. There is also the more general coercion
function as() (see ?as).

I hope this helps,
 John

------------------------------
John Fox, Professor
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
web: socserv.mcmaster.ca/jfox

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org]
On
> Behalf Of Arup
> Sent: February-06-09 1:51 AM
> To: r-help at r-project.org
> Subject: [R] How to convert Charagter variables into numeric
> 
> 
> I am importing a dataset in R where some of the variable are numerical and
> some of them are character...but the problem is that R is treating
> numerical variables as character (I am using "is.character" to
judge the
> type). Now the question is how can I convert these character variables
into
> numeric and also let me know about the other conversion like "numeric
to
> categorical","numeric to continuous" etc.Thank you.
> 
> Arup
> --
> View this message in context:
http://www.nabble.com/How-to-convert-Charagter-
> variables-into-numeric-tp21867485p21867485.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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