I have used R for years but run into a seemingly simple problem involving
'ifelse'. condensed code like this
a=c(2,NA,NA,NA,2,2,NA,2,NA,2)
b=c(NA,1,1,NA,2,2,2,2,2,2)
#I want to combined a and b into c so that c would be a valid number either a
or b is not missing
c=ifelse(a==1|b==1,1,ifelse(a==2|b==2,2,NA))
cbind(a,b,c)
a b c
[1,] 2 NA NA
[2,] NA 1 1
[3,] NA 1 1
[4,] NA NA NA
[5,] 2 2 2
[6,] 2 2 2
[7,] NA 2 NA
[8,] 2 2 2
[9,] NA 2 NA
[10,] 2 2 2
look at rows 1, 7 and 9, c supposes to be 2 but got NA instead. seemingly, the
second 'ifelse' doesn't perform as it supposes.
my R version is 2.12.2
any suggestion
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