How to write an R if statement that selects between 2 data columns and returns one based on the valu-CodePudding

I Have a data set that looks like this: input data

I need R to take create a new column "Ref" and choose between Allele_A & Allele_B based on the value of Hom_Ref_A.

If Hom_Ref_A = 2 it should be choosing from Allele_A, and if Hom_Ref_A = 0 it should choose from Allele_B and write these to the Ref column

and the reverse for an "Alt" column (Allele_A if Hom_Ref_A = 0, and Allele_B if Hom_Ref_A = 2)

The output should look like this: result

I would really appreciate any help on this

CodePudding user response：

With case_when:

df %>%
  mutate(
    Ref = case_when(
      Hom_Ref_A == 2 ~ Allele_A,
      Hom_Ref_A == 0 ~ Allele_B
      ),
    Alt = case_when(
      HomRef_A == 2 ~ Allele_B,
      HomRef_A == 0 ~ Allele_A
    )
  )