Combine same column from different data frames

Question

I'm new with R, and would like to do some basic things. I have three data frames with a column with the same name. In each data frame a different value is registered. (In my real data there are more values and off course NA)

Df1

   Value
 A  1
 B  NA
 C  NA
 D  NA

Df2

   Value
 A  NA
 B  NA
 C  2
 D  NA

Df3

   Value
 A  NA
 B  NA
 C  NA
 D  3

I want to combine the three data frames so I can complete the column. So I get this:

Df

   Value
 A  1
 B  NA
 C  2
 D  3

How can I do this in R?

Thank you.

Answer 1

Using dplyr::coalesce:

library(dplyr)
Df <- data.frame(Value = coalesce(Df1$Value, Df2$Value,Df3$Value),
                 row.names = row.names(Df1))
Df
#   Value
# A     1
# B    NA
# C     2
# D     3

data

Df1 <- read.table(text="
Value
A  1
B  NA
C  NA
D  NA",strin=F,h=T)

Df2  <- read.table(text="
Value
A  NA
B  NA
C  2
D  NA",strin=F,h=T)

Df3  <- read.table(text="
Value
A  NA
B  NA
C  NA
D  3",strin=F,h=T)

Answer 2

One option in base R is pmin/pmax (assuming that there is only a single non-NA element at the same location). Place the objects in a list (with mget), and use pmin with do.call

do.call(pmin, c(mget(paste0("Df", 1:3)), na.rm = TRUE))
#  Value
#A     1
#B    NA
#C     2
#D     3

data

Df1 <- structure(list(Value = c(1L, NA, NA, NA)), class = "data.frame", row.names = c("A", 
"B", "C", "D"))

Df2 <- structure(list(Value = c(NA, NA, 2L, NA)), class = "data.frame", row.names = c("A", 
"B", "C", "D"))

Df3 <- structure(list(Value = c(1L, NA, 2L, 3L)), class = "data.frame", row.names = c("A", 
"B", "C", "D"))