R help - Apr 2012 - Help with creating conditional categorical variables in R

Hi,
I am stuck with creating a conditional categorical variable in R
If my dataframe  data_2  has 3 variables A,B,C    I want to create variable D
which would be something like :

data_2$D <- ifelse(data_2$A < data_2$B & promotion_ind
=="N",1,0),
this throws up an error "In Ops.factor(data_2$A,data_2$B) :
  < not meaningful for factors

I have tried converting the dataframe to a matrix using
data.matrix(data_2, rownames.force = NA) but that did not help,

Can anybody tell me how to go about doing this?

Thanks in advance,
Doy

American Express made the following annotations on Wed Apr 18 2012 05:37:16 

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American Express a ajouté le commentaire suivant le Wed Apr 18 2012 05:37:16 

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Your problem is that columns A & B contain something that can't be
ordered. (Likely "factor" (=categorical) data like Male / Female
rather than numeric like 10 and 5)

Use str(data_2) to see what classes your data are -- they sometimes
get converted in unexpected ways if you aren't careful in setting up
your data.frame. If this doesn't clear things up, please type
dput(head(data_2, 20)) at the console and copy and paste the result
into a follow up email.

Don't do the data.matrix thing without understanding the current class
of your data -- you'll get strange conversions.

Hope this helps,
Michael

On Wed, Apr 18, 2012 at 8:36 AM, Dwaipayan Dasgupta
<Dwaipayan.Dasgupta at aexp.com> wrote:
> Hi,
> I am stuck with creating a conditional categorical variable in R
> If my dataframe ?data_2 ?has 3 variables A,B,C ? ?I want to create variable
D which would be something like :
>
> data_2$D <- ifelse(data_2$A < data_2$B & promotion_ind
=="N",1,0),
> this throws up an error "In Ops.factor(data_2$A,data_2$B) :
> ?< not meaningful for factors
>
> I have tried converting the dataframe to a matrix using
> data.matrix(data_2, rownames.force = NA) but that did not help,
>
> Can anybody tell me how to go about doing this?
>
> Thanks in advance,
> Doy
>
> American Express made the following annotations on Wed Apr 18 2012 05:37:16
>
>
******************************************************************************
>
> "This message and any attachments are solely for the intended
recipient and may contain confidential or privileged information. If you are not
the intended recipient, any disclosure, copying, use, or distribution of the
information included in this message and any attachments is prohibited. If you
have received this communication in error, please notify us by reply e-mail and
immediately and permanently delete this message and any attachments. Thank
you."
>
> American Express a ajout? le commentaire suivant le Wed Apr 18 2012
05:37:16
>
> Ce courrier et toute pi?ce jointe qu'il contient sont r?serv?s au seul
destinataire indiqu? et peuvent renfermer des renseignements confidentiels et
privil?gi?s. Si vous n'?tes pas le destinataire pr?vu, toute divulgation,
duplication, utilisation ou distribution du courrier ou de toute pi?ce jointe
est interdite. Si vous avez re?u cette communication par erreur, veuillez nous
en aviser par courrier et d?truire imm?diatement le courrier et les pi?ces
jointes. Merci.
>
>
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>
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>
>
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>
>
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