R 配对列索引

Question

假设我有两个矩阵，A 和 B:

mth <- c(rep(1:5,2))
day <- c(rep(10,5),rep(11,5)) 
hr <- c(3,4,5,6,7,3,4,5,6,7)  
v <- c(3,4,5,4,3,3,4,5,4,3)  
A <- data.frame(cbind(mth,day,hr,v))

year <- c(2008:2012)
mth <- c(1:5)  
B <- data.frame(cbind(year,mth)) 

我想要的应该是这样的:

mth <- c(rep(2008:2012,2))  
day <- c(rep(10,5),rep(11,5))  
hr <- c(3,4,5,6,7,3,4,5,6,7)  
v <- c(3,4,5,4,3,3,4,5,4,3)  
A <- data.frame(cbind(mth,day,hr,v)) 

基本上我需要的是将A中的第m列更改为B中的列年份，也许我没有搜索正确的关键字，我无法得到我想要的(我试过which())，请帮忙，谢谢你。

Answer 1

A2 <- merge(A,B, by = "mth")[ , -1]
names(A2)[(which(names(A2)=="year"))] <- "mth"
> A2
   day hr v  mth
1   10  3 3 2008
2   11  3 3 2008
3   11  4 4 2009
4   10  4 4 2009
5   11  5 5 2010
6   10  5 5 2010
7   11  6 4 2011
8   10  6 4 2011
9   10  7 3 2012
10  11  7 3 2012