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Question: issue with ifelse statement
1
Entering edit mode

Hi,

I have a file like this:

> head(aa)
  PLASER CURRELIG RTNPTHY
1      1        1       1
2      1        1       1
3      2        1       2
4      1        1       2
5      1        1       2
6      1        1       2

I have to create another column, say "new" which will satisfy these conditions:

PLASER=2 AND CURRELIG=1  -> new=2
RTNPHY=1 AND CURRELIG=1    -> new=1

I tried running this command:

 aa$new <- ifelse(aa$CURRELIG==1 & aa$PLASER==2, 2, ifelse(aa$CURRELIG==1 & aa$RTNPHY==1,1,NA))

but I am getting this output which is not correct:

> head(aa)
  PLASER CURRELIG RTNPTHY new
1      1        1       1  NA
2      1        1       1  NA
3      2        1       2   2
4      1        1       2  NA
5      1        1       2  NA
6      1        1       2  NA

Can someone please help with this?

Thanks ANA

ADD COMMENTlink 5 months ago anamaria • 40 • updated 5 months ago shawn.w.foley • 670
4
Entering edit mode

It looks like the ifelse command isn't meant to be nested like you have in your code, it's for binary output and it seem like you want three options (1, 2, or NA). From the man page:

Usage:
     ifelse(test, yes, no)
Arguments:
    test: an object which can be coerced to logical mode.
    yes: return values for true elements of ‘test’.
    no: return values for false elements of ‘test’.

It might be easier to run:

aa$new <- NA
aa$new[aa$CURRELIG==1 & aa$PLASER==2] <- 2
aa$new[aa$CURRELIG==1 & aa$PLASER==1] <- 1

This will generate a new column of NAs, then replace the NAs with 1 when both CURRELIG==1 & PLASER==2 or replace them with 2 when both CURRELIG==1 & PLASER==1.

ADD COMMENTlink 5 months ago shawn.w.foley • 670
Entering edit mode
0

So I did why you posted above and when I do:

 > dim(aa[aa$new==1,])
 [1] 1513    4
> dim(aa[aa$new==2,])
[1] 946   4

while:
> dim(aa)
[1] 1651    4

why do total count of "1" and "2" exceed to number of entries in this data frame?

ADD REPLYlink 5 months ago
anamaria
• 40

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