How to merge 2 columns on 1 column
dataframe, r
Solution
You can use `merge` with argument `by='row.names'` and `sort=F` (as pointed out by Matthew Plourde) to not let `merge` mess up the order:
> merge(df1, df2, by='row.names', sort=FALSE, all=TRUE)[c("var1", "var2", "var3")]
var1 var2 var3
1 a f a
2 b g b
3 c h c
4 d i d
5 e j e
6 <NA> <NA> i
7 <NA> <NA> f
8 <NA> <NA> g
9 <NA> <NA> h
10 <NA> <NA> j
Problem
I would like to merge 2 df's where in df1 contains 2 columns and df2 1 column, how to apply function merge in this case? Here is sample case: ``` df1 <- data.frame(var1=letters[1:5],var2=letters[6:10]) df2 <- data.frame(var3=letters[1:10]) ``` False attempt: ``` merge(df1,df2,by.x=c("var1","var2"),by.y="var3",all.y=TRUE) ``` How to merge these two df's so that the matching search uses both columns of df1 (var1 & var2) and operates on df2 (var3)? Desired output: ``` var1 var2 var3 1 a f a 2 b g b 3 c h c 4 d i d 5 e j e 6 <NA> <NA> f 7 <NA> <NA> g 8 <NA> <NA> h 9 <NA> <NA> i 10 <NA> <NA> j ``` EDIT: Improved data (I hope): ``` df1 <- data.frame(var1=c(letters[1:5],rep("x",5)),var2=c(letters[6:10],rep("x",5))) df2 <- data.frame(var3=letters[1:10]) ``` Desired output: ``` var1 var2 var3 1 a f a 2 b g b 3 c h c 4 d i d 5 e j e 6 x x f 7 x x g 8 x x h 9 x x i 10 x x j ```