[R] creating dummy with loop command

Dimitri Liakhovitski ld7631 at gmail.com
Fri Apr 23 20:27:44 CEST 2010

I think what David is saying: just take those 2 variables you have and
specify them as factors. Assuming your data frame is called "MyData":


This way R will know they are not numeric variables but categorical
variables. Then, when you do analyses using those variables, R will
treat them as such and will build dummies "automatically" (e.g., if
you use regression, etc.).
Actually - it'd be nice to know what you are building your dummies for.


On Fri, Apr 23, 2010 at 11:34 AM, David Winsemius
<dwinsemius at comcast.net> wrote:
> On Apr 23, 2010, at 11:26 AM, serdal ozusaglam wrote:
>> Dear R users,
>> I have a simple question (probably) but i couldnt how to find a solution
>> for that.
>> i am using 2 digit industry codes and 3 digit industry codes for my model,
>> and i need to create dummies for the industries. The case is simple for the
>> 2-digit industries since there are not that mcuh of them, so i am creating
>> my dummies as following
>> ind_2da<-(ind_2d==11)#for the 11th industry
>> ind_2dc<-(ind_2d==12)#for the 12th industry and so on so forth ... then i
>> directly put the dummy into the regression which works well.
>> but creating dummies for the 3-digit is rather complicated since there are
>> alot of sub-industries, for example:111,112,113...119 and this is just for
>> the 11th industry
>> so when i consider the codes continues till 40, it would be exhausting to
>> do it by hand.
>> so i was looking for the loop commands to do it faster but since i am a
>> newbie i got lost in it.
>> so is there some one who can help me for this problem?
> Don't use dummies.
> ?factor
> --
> David Winsemius, MD
> West Hartford, CT
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Dimitri Liakhovitski
Dimitri.Liakhovitski at ninah.com

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