[R] Subsetting with missing data

Simply put, I want to subset the data frame 'a' where 'y=0'. a - as.data.frame(cbind(x=1:10, y=c(1,0,NA,1,0,NA,NA,1,1,0))) a x y 1 1 1 2 2 0 3 3 NA 4 4 1 5 5 0 6 6 NA 7 7 NA 8 8 1 9 9 1 10 10 0 names(a) [1] x y table(a$y) 0 1 3 4 table(a$y, useNA=always) 0

Re: [R] Subsetting with missing data

Hello, From the help page for ?`==` Note Do not use |==| and |!=| for tests, such as in |if| expressions, where you must get a single |TRUE| or |FALSE|. Unless you are absolutely sure that nothing unusual can happen, you should use the |identical

Re: [R] Subsetting with missing data

It makes sense if you think it through. Your index vector is a$y==0 [1] FALSE TRUENA FALSE TRUENANA FALSE FALSE TRUE and ?[ says NAs in indexing: When extracting, a numerical, logical or character 'NA' index picks an unknown element and so returns 'NA' in the

Re: [R] Subsetting with missing data

HI, Try this: subset(a,y==0) #    x y #2   2 0 #5   5 0 #10 10 0 #or subset(a,y%in%0) #    x y #2   2 0 #5   5 0 #10 10 0 A.K. - Original Message - From: Robin Jeffries rjeffr...@ucla.edu To: r-help@r-project.org Cc: Sent: Wednesday, August 15, 2012 4:06 PM Subject: [R] Subsetting