[R] ifelse choices in a data.frame?

[Mark Knecht]

That's much better. thanks!

I was sure I'd looked at that but then for some reason stuck with just if.

Again, as a total a newb I appreciate the help.

- Mark

On Sun, Jul 19, 2009 at 2:26 PM, Duncan Murdoch<murdoch at stats.uwo.ca> wrote:
> On 19/07/2009 5:17 PM, Mark Knecht wrote:
>>
>> Hi,
>>   In my data.frame I  wanted to essentially write
>>
>> If(Test) c*d else c+d
>>
>> but that doesn't work. I found I could do it mathematically, but it
>> seems forced and won't scale well for nested logic. I have two
>> examples below writing columns e & f, but I don't think the code is
>> self-documenting as it depends on knowing that Test is a TRUE/FALSE.
>>
>>   Is there a better way to do the following?
>>
>> Thanks,
>> Mark
>>
>>
>> DF <- data.frame(cbind(a=1:4, b=1:2, c=1:8, d=1:16, e=0, f=0))
>> DF$Test <- with(DF, a == b)
>>
>> DF$e = (DF$c*DF$d) * DF$Test + (DF$c+DF$d) * !DF$Test
>>
>> DF$f = with(DF, (c*d)*Test + (c+d)*!Test)
>
> Use ifelse().
>
> DF$f <- with(DF, ifelse(a == b, c*d, c+d))
>
> Duncan Murdoch
>
>>
>> DF
>>
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>
>