R Overwrite column values with non NA values from column in separate dataframe

Question

I have a dataframe 'df1' with a lot of columns, but the ones of interest are:

Number	Code
1
2
3
10
11	AMRO
4
277
2100	BLPH

And I have another dataframe 'df2' with a lot of columns, but the ones of interest are:

Number	Code
1	AMCR
2	AMCR
3	BANO
10	BAEA
12	AMRO
4	NA
277	NA
2100	NA

I want matching values in the 'Number' columns of 'df1' and 'df2' to lead to values in the 'Code' column in 'df2' to overwrite the 'Code' values in 'df1' as long as the 'Code' values in 'df2' don't contain an NA, so that the final result of 'df1' looks like:

Number	Code
1	AMCR
2	AMCR
3	BANO
10	BAEA
11	AMRO
4
277
2100	BLPH

Thank you for your help!

Answer 1

We can do

library(powerjoin)
power_left_join(df1, df2, by = "Number", conflict = coalesce)

-output

Number Code
1      1 AMCR
2      2 AMCR
3      3 BANO
4     10 BAEA
5     11 AMRO
6      4 <NA>
7    277 <NA>
8   2100 BLPH

---

Or to do an overwrite, use data.table

library(data.table)
setDT(df1)[df2, Code := fcoalesce(Code, i.Code), on = .(Number)]

-output

> df1
   Number   Code
    <int> <char>
1:      1   AMCR
2:      2   AMCR
3:      3   BANO
4:     10   BAEA
5:     11   AMRO
6:      4   <NA>
7:    277   <NA>
8:   2100   BLPH

data

df1 <- structure(list(Number = c(1L, 2L, 3L, 10L, 11L, 4L, 277L, 2100L
), Code = c(NA, NA, NA, NA, "AMRO", NA, NA, "BLPH")), 
class = "data.frame", row.names = c(NA, 
-8L))

df2 <- structure(list(Number = c(1L, 2L, 3L, 10L, 12L, 4L, 277L, 2100L
), Code = c("AMCR", "AMCR", "BANO", "BAEA", "AMRO", NA, NA, NA
)), class = "data.frame", row.names = c(NA, -8L))