[R-sig-Epi] question re: recoding in R

[Alexandre Aguiar]

Em Qua 25 Jul 2007, Lynn Disney escreveu:
> I need to create dummy variables, for an ID when 3 conditions exist. I
> am having problems figuring out how to do this. For example, I want
> variablea=1 and variableb=1 hand variablec=1 and then have variableD
> turned into a 1 when these conditions are true and 0 when any one of
> them are false.

Ooops! This one even I know.

d <- 0
if( a & b & c ) d <- 1

Depending on the expected proportions of d==1 and d==0 and how many tests you 
are going to do, starting with d <- 1 and then testing for !( a & b & c ) 
could be faster. However, the code above should be good enough in 99.9% of 
applications.

Maybe you would like to check out [http://finzi.psych.upenn.edu/nmz.html]. It 
has answsered 100% of my questions so far.

Best wishes.

Alexandre

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