Hi Emily,
I haven't tested this exhaustively, but it seems to work:
df<-data.frame(id=2001:3300,yrssmoke=sample(1:40,1300,TRUE),
cigsdaytotal=sample(1:60,1300,TRUE),yrsquit=sample(1:20,1300,TRUE))
dfNA<-sapply(df$id,"%in%",c(2165,2534,2553,2611,2983,3233))
# create your NA values
df[dfNA,c("yrsquit","packyrs")]<-NA
# since you know the NA id values
df[dfNA,"yrsquit"]<-0
df[dfNA,"packyrs"]<-df[dfNA,"yrssmoke"]*df[dfNA,"cigsdaytotal"]/20
Jim
On Sat, May 7, 2016 at 8:19 AM, Chang, Emily <emily.cha...@ucsf.edu> wrote:
> Dear all,
>
> I am reading a modest dataset (2297 x 644) with specific values I want to
> change. The code is inelegant but looks like this:
>
> df <- read.csv("mydata.csv", header = TRUE, stringsAsFactors = FALSE)
>
> # yrsquit, packyrs missing for following IDs. Manually change.
> for(myid in c(2165, 2534, 2553, 2611, 2983, 3233)){
> temp <- subset(df, id == myid)
> df[df$id == myid , "yrsquit"] <- 0
> temp.yrssmoke <- temp$age-(temp$agesmoke+temp$yrsquit)
> df[df$id == myid , "yrssmoke"] <- temp.yrssmoke
> df[df$id == myid , "packyrs"] <- (temp$cigsdaytotal/20)*(temp.yrssmoke)
> }
>
> If I run just the first line and then the for loop, it works.
> If I run the first line and for loop together, yrsquit is properly replaced
> to == 0, but packyrs is NA still.
>
> Obviously there's many ways around this specific problem, but I was wondering
> what the issue is here, so as to look out for and avoid it in the future.
>
> Apologies for the lack of reproducible code; I haven't yet reproduced the
> problem with generated data.
>
> Much thanks in advance.
>
> Best regards,
> Emily
>
> [[alternative HTML version deleted]]
>
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