Issue replacing dataset values from read data
1. It's not immediately clear why you need the line "temp <- subset(df, id == myid)" 2. The objects described by "temp$age", temp$agesmoke, and temp$yrsquit are all vectors. So temp.yrssmoke is also a vector. This means that when you replace, it should be with "<- temp.yrssmoke[i]", where "i" is the (row) number you're looping over (note "temp" re-numbers rows to 1 through 6, another reason to remove the "temp" line). 3. Ditto for " <- (temp$cigsdaytotal[i]/20)*(temp.yrssmoke[i]) " Hope this helps! Bill W. Michels, Ph.D.
On Fri, May 6, 2016 at 3:19 PM, Chang, Emily <Emily.Chang2 at 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
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