[R] Problem with ifelse statement

[Daniel Malter]

The following works:

socstat=rep(c("A","B","D","E"),each=100)
male=rep(1:4,100)
socstat2=ifelse(socstat=="B"&male==4,"C",socstat)

Therefore, your code should work if it were the code you want (in other
words, it's a logic not a coding problem). Your mistake is that you recode
ALL social statuses of observations that are not "B"  AND MALE!=4 into Bs.
That is, all observations with social status not B (A,D,E,F,G,H,I,J...)  are
recoded into Bs. That is certainly not what you want. I think what you want
is:

data$SOCIAL_STATUS<-ifelse(data$SOCIAL_STATUS=="B" & data$MALE>4, "C",
data$SOCIAL_STATUS)

Right?
Daniel


-------------------------
cuncta stricte discussurus
-------------------------

-----Ursprüngliche Nachricht-----
Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
Auftrag von Mark Na
Gesendet: Tuesday, June 23, 2009 6:33 PM
An: r-help at r-project.org
Betreff: [R] Problem with ifelse statement

Hi R-helpers,

I am trying to use this ifelse statement to recode a variable:
> data$SOCIAL_STATUS<-ifelse(data$SOCIAL_STATUS=="B" & data$MALE>4, "C", 
> "B")

(i.e., if social status is B and there are more than 4 males, then recode
social status to C; otherwise, leave it B)

But, it's not working. See the below R output. Notice that there were
71 "B" observations before the re-code but 2098 "B" observations after the
re-code. The only thing my code should do is REDUCE the number of "B"
observations, not increase them.

Can anyone see what I'm doing wrong? Thanks!

Thanks, Mark Na


> str(data)
'data.frame':   2100 obs. of  13 variables:
 $ DATE           :Class 'Date'  num [1:2100] 14399 14399 14399 14399 14399
...
 $ OBS            : Factor w/ 7 levels "AJG","LEB","MB",..: 3 3 3 3 3
3 3 3 3 3 ...
 $ POND_ID        : Factor w/ 118 levels "1","10","100",..: 86 86 86
86 86 86 86 86 86 86 ...
 $ STATUS         : num  1 1 1 1 1 1 1 1 1 1 ...
 $ SPECIES        : Factor w/ 25 levels "AGWT","AMAV",..: 16 16 12 12
4 7 7 7 7 3 ...
 $ SOCIAL_STATUS  : Factor w/ 9 levels "","A","B","D",..: 5 2 5 2 5 5
5 5 2 8 ...
 $ COUNT_OF_GROUPS: num  1 1 1 1 1 3 3 3 1 2 ...
 $ MALE           : num  1 1 1 1 1 1 1 1 1 0 ...
 $ FEMALE         : num  1 0 1 0 1 1 1 1 0 0 ...
 $ NOSEX          : num  0 0 0 0 0 0 0 0 0 2 ...
 $ UPLAND         : num  0 0 0 0 0 0 0 0 0 0 ...
 $ TAG            : num  0 0 0 0 0 0 0 0 0 0 ...
 $ COMMENT        : chr  "" "" "" "" ...


> length(which(data$SOCIAL_STATUS=="B"))
[1] 71

> data$SOCIAL_STATUS<-ifelse(data$SOCIAL_STATUS=="B" & data$MALE>4, "C", 
> "B")

> length(which(data$SOCIAL_STATUS=="B"))
[1] 2098

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