匹配R中某个表中的数据集

我希望这个过程

原来的一个

A     B
LN1   1
LN2   2
LN3   3

桌子

我想要什么

A     B
LN1   1
LN2   2
LN3   3
LN4   1

---

我想粘贴原始的一个，以引用像LN1这样的带有属性的表（LN1-1；LN4-1导致了该表）。。。如何生成代码？

尝试从

dplyr

包中加入函数！

df1 = read.table(text = "
A     B
LN1   1
LN2   2
LN3   3
", header=T, stringsAsFactors=F)

df2 = data.frame(A = c("LN1","LN4"), stringsAsFactors = F)

library(dplyr)

left_join(df2, df1, by="A") %>%         # join datasets
  mutate(B = unique(B[!is.na(B)])) %>%  # replace NAs in column B with the unique non-NA value
  bind_rows(df1) %>%                    # bind original dataset
  distinct()                            # keep distinct rows

#     A B
# 1 LN1 1
# 2 LN4 1
# 3 LN2 2
# 4 LN3 3

df1 = read.table(text = "
A     B
LN1   1
LN2   2
LN3   3
", header=T, stringsAsFactors=F)

df2 = data.frame(A = c("LN1","LN4"), stringsAsFactors = F)

library(dplyr)

left_join(df2, df1, by="A") %>%         # join datasets
  mutate(B = unique(B[!is.na(B)])) %>%  # replace NAs in column B with the unique non-NA value
  bind_rows(df1) %>%                    # bind original dataset
  distinct()                            # keep distinct rows

#     A B
# 1 LN1 1
# 2 LN4 1
# 3 LN2 2
# 4 LN3 3