[R] Assigning a variable value based on multiple columns

[Patrick Coulombe]

Hi Jason,

I think that the easiest for you would be to keep your current elseif
statements as is, but change your NA into something else (e.g., -999,
or anything else). To do this in one line, you can use the package
"gdata".

In this code, I assume that your data are stored in the variable "dataset":


###########
#install package gdata if not yet installed
install.packages("gdata")

#load package gdata
library(gdata)

#change NA into -999
dataset <- NAToUnknown(dataset, -999)


#do your ifs/ifelses here...
#...
#...


#change -999 back into NA
dataset <- unknownToNA(dataset, -999)
############


And that should do it.

Hope this helps,
Patrick


2013/4/24 Jason Stout, M.D. <jason.stout at duke.edu>
>
> Hi All,
>
> I'm hoping someone can help me with a relatively simple problem.  Take the following dataset:
>
> ID    Diabetes    ESRD    HIV    Contact
> 1        0            0            NA        0
> 2        1            0            NA        0
> 3        NA          1            0        0
> 4        0            NA          0        1
> 5        1            1            1        0
>
> I want to generate a column called TSTcutoff based on the values in the row.  TSTcutoff would be the lower of 15 (if Diabetes=ESRD=HIV=Contact=0), 10 (if Diabetes or ESRD=1 AND HIV=Contact=0), or 5 (if HIV OR Contact=1).  I was thinking this could be done with a series of IFELSE statements, but the NA values make this more challenging.  I want to ignore NA values when calculating TSTcutoff.  So the final dataset should look like this:
>
> ID    Diabetes    ESRD    HIV    Contact     TSTcutoff
> 1        0            0            NA        0        15
> 2        1            0            NA        0         10
> 3        NA          1            0        0            10
> 4        0            NA          0        1            5
> 5        1            1            1        0            5
>
> Thanks for any suggestions.
>
> Jason Stout, MD, MHS
> Box 102359-DUMC
> Durham, NC 27710
> FAX 919-681-7494
>
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>
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