R- merge 3 or more dataframes

Question

I have read data from 3 different files into 3 different dataframes. I have tried merge function but doesnot seem to give me the desired output. My dataframes are:

df1:

someName    someMOD someID
A   T754(P),M691(O),S692(P),S694(P),S739(P),S740(P),S759(P),S762(P) 1
B   S495(P) 2
C   S162(P),Q159(D) 3
D   S45(P),C47(C),S48(P),S26(P) 4
E   S18(P)  5

df2:

someName    someMOD someID
C   S162(P),Q159(D) 3
D   S45(P),C47(C),S48(P),S26(P) 4
F   S182(P) 6
E   S18(P)  5
Z   Q100(P) 9
A   T754(P),M691(O),S694(P),S739(P),S740(P) 1

df3:

someName    someMOD someID
A   T754(P),M691(O),S692(P),S694(P),S739(P),S740(P),S759(P) 1
B   S495(P) 2
D   S45(P),C47(C),S48(P),S26(P) 4
E   S18(P)  5
F   S182(P) 6
L   Z182(P) 8
C   S162(P),Q159(D) 3

I would like an output like the following which is merged by someID column:

Any help is really appreciated.Thanks.

Answer 1

Use Reduce to merge multiple data frames together. One annoying thing about Reduce is that it passes the underlying function exactly 2 arguments, so you have to work around that.

mymerge <- function(x, y)
merge(x, y, by=c("someName", "someID"), all=TRUE))

Reduce(mymerge, list(df1, df2, df3))

Answer 2

library(data.table)

dt1 <- data.table(df1, key="someName,someID")
dt2 <- data.table(df2, key="someName,someID")
dt3 <- data.table(df3, key="someName,someID")

DT <- dt1[dt2[dt3]]