apply merge to a list of data.frames

Question

I have a list of data.frames with just one column and a character value:

> list.df[c(1,5,8)]
$1
     X..1L..
1      A
2      B
3      C
4      D
5      E
6      F
7      G
8      H

$5
   X..5L..
1    A
2    C
3    D
4    F
5    G

$8
   X..8L..
1   A
2   D
3   F
4   G
5   H
6   I

And another data.frame

> df
  V2  V5      V9
1  A  31 0.13029
2  B  80 0.29443
3  C 166 0.01354
4  D  11 0.39589
5  E  62 0.61794
6  F  40 0.35808
7  G  31 0.62581
8  H  54 0.24983
9  I  19 0.47199
10 J  97 0.26518

I would like to merge each data.frame in the list with df, I've tried creating a function func <- function(x,y){merge(x, y, by.x=x[,1], by.y=y[,1])} and then applying it to the list but it does not work.

lapply(list.df, func, list.df, df)

I know that I can split list.df in several data.frames and then merge each of them individually, but I was wondering if there is a way to do it in the list

Thanks

Answer 1

You have two mistakes. One in your function and the other one in how you call your function:

func <- function(x,y){merge(x, y, by.x=names(x)[1], by.y=names(y)[1])}
lapply(list.df, func, df)