[R] New Variable from Several Existing Variables

[Don MacQueen]

If your data is in a matrix named "orgdata" :

newvar <- apply(orgdata , 1, function(arow, if (all(arow=='Yes')) 
'Yes' else 'No'

newdata <- cbind(orgdata, newvar)

finaloutcome <- newdata[ newvar=='Yes',]


The key to this is the apply() function.

I might have missed some parentheses...

There are other ways; this is just one. I might think of a simpler 
one if I gave it more time...

-Don

At 4:40 PM -0800 2/26/10, wookie1976 wrote:
>I am new to R, but have been using SAS for years.  In this transition period,
>I am finding myself pulling my hair out to do some of the simplest things.
>An example of this is that I need to generate a new variable based on the
>outcome of several existing variables in a data row.  In other words, if the
>variable in all three existing columns are "Yes", then then the new variable
>should also be "Yes", however if any one of the three existing variables is
>a "No", then then new variable should be a "No".  I would then use that new
>variable as an exclusion for data in a new or existing dataset (i.e., if
>NewVariable = "No" then delete):
>
>Take this:
>Column1, Column2, Column3
>Yes, Yes, Yes
>Yes, No, Yes
>No, No, No
>No, Yes, No
>Yes, Yes, No
>
>Generate this:
>Column1, Column2, Column3, NewVariable1
>Yes, Yes, Yes, Yes
>Yes, No, Yes, No
>No, No, No, No
>No, Yes, No, No
>Yes, Yes, No, No
>
>And end up with this:
>Column1, Column2, Column3, NewVariable1
>Yes, Yes, Yes, Yes
>
>Any suggestions on how to efficiently do this in either the existing or a
>new dataset?
>
>Thanks,
>--
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>Sent from the R help mailing list archive at Nabble.com.
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062