how to create a new column from two columns with conditions
Hello, Inline. ?s 22:44 de 29/04/20, Ana Marija escreveu:
Hi Rui, thanks for getting back to me so I tried your method and I got:
sum(b$PHENO==2, na.rm=T)
[1] 828
sum(b$PHENO==1, na.rm=T)
[1] 859 Can you please tell me if b$PHENO <- (b$FLASER == 2 | b$PLASER == 2) + 1L just assigns PHENO=2 if b$FLASER == 2 | b$PLASER == 2 and everything else is 1?
Yes, that's it. If b$FLASER == 2 | b$PLASER == 2 returns TRUE then adding 1 will give TRUE + 1 -> 1 + 1 -> 2 This is because logical values are internally coded as integers 0 and 1. And if the condition returns FALSE it becomes FALSE + 1 -> 0 + 1 -> 1 In both cases the result is what you want.
Please see how my data looks like:
sum(b$FLASER==2, na.rm=T)
[1] 92
sum(b$FLASER==1, na.rm=T)
[1] 1533
sum(b$PLASER==1, na.rm=T)
[1] 850
sum(b$PLASER==2, na.rm=T)
[1] 806
dim(b)
[1] 1698 5
unique(b$FLASER)
[1] 1 3 2 NA
unique(b$PLASER)
[1] 1 2 3 NA
What I write above is valid even if your data contains NA's, like it does. This is because (TRUE | x) == (x | TRUE) == TRUE even if x is NA. This is an example with some NA values in the data. set.seed(1234) b <- rbind(b, b) i <- sample(nrow(b), 3) b$FLASER[i] <- NA i <- sample(nrow(b), 2) b$PLASER[i] <- NA b$PLASER[10] <- 2 b$PHENO <- (b$FLASER == 2 | b$PLASER == 2) + 1 b As you can see, row 5: b$FLASER is NA, b$PLASER == 2 evaluates to TRUE -> b$PHENO is TRUE row 10: b$FLASER == 2 evaluates to TRUE, b$PLASER is NA -> b$PHENO is TRUE So the code is not broken by NA's Hope this helps, Rui Barradas
On Wed, Apr 29, 2020 at 4:10 PM Rui Barradas <ruipbarradas at sapo.pt> wrote:
Hello, Here is another way. The condition returns FALSE/TRUE or 0/1. Add 1 to get the expected result. It has the advantage of being faster. b$PHENO <- (b$FLASER == 2 | b$PLASER == 2) + 1L Hope this helps, Rui Barradas ?s 20:42 de 29/04/20, Ana Marija escreveu:
Thanks, I did this: b$PHENO<- ifelse(b$FLASER ==2 | b$PLASER ==2, 2, 1) On Wed, Apr 29, 2020 at 2:36 PM Ivan Krylov <krylov.r00t at gmail.com> wrote:
On Wed, 29 Apr 2020 14:19:18 -0500 Ana Marija <sokovic.anamarija at gmail.com> wrote:
My conditions for creating a new column PHENO would be this: if FLASER or PLASER =2 then PHENO=2 otherwise PHENO=1
On Wed, 29 Apr 2020 15:30:45 -0400 "Patrick (Malone Quantitative)" <malone at malonequantitative.com> wrote:
If you don't mind using tidyverse, you can do this easily with if_else.
...and if you want to stay with base R, you can use the ifelse function. -- Best regards, Ivan
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