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library(dplyr, warn.conflicts = FALSE)
DF <- data.frame(A01 = c(4.87, 4.91, 4.89, 4.85, 4.84, NA),
A01_CD = c(4.87, NA, 4.86, NA, NA, 5.95))
DF
#> A01 A01_CD
#> 1 4.87 4.87
#> 2 4.91 NA
#> 3 4.89 4.86
#> 4 4.85 NA
#> 5 4.84 NA
#> 6 NA 5.95
DF <- DF %>% mutate(A01 = ifelse(is.na(A01), A01_CD, A01),
A01_CD =NA)
DF
#> A01 A01_CD
#> 1 4.87 NA
#> 2 4.91 NA
#> 3 4.89 NA
#> 4 4.85 NA
#> 5 4.84 NA
#> 6 5.95 NA
Created on 2020-09-19 by the reprex package (v0.3.0)