合并2个数据框并更新R中的列值[重复]

Question

我有 2 个数据框，

R1 <- c("15515","5156","65656","1566", "2857")
RC <- c("A","X","B","Z","A")
R2 <- c("515","5156.11-","415-","1455-","886")
df <- data.frame(R1,RC,R2)

R1 <- c("15515","8888","65656","1566")
R2 <- c("111","222","333","444")
R3 <- c("999","888","777","666")
df2 <- data.frame(R1,R2,R3)

我需要先左加入 R1 上的 df，

要达到的条件，

1. if df$R1 != df2$R1
  df$R2 <- df$R2  (As it is in df)
  
2. if df$R1 == df2$R1 & (df$RC == A | df$RC == B) then,
  df$R2 <- df2$R2
  
3. if df$R1 == df2$R1 & (df$RC != A | df$RC != B) then,
  df$R2 <- df2$R3

输出可能看起来像

 R1        RC        R2
15515      A        111
5156       X        5156.11-
65656      B        333
1566       Z        666
2857       A        886

我尝试执行以下代码，

df$R1[which(df$R1 == df2$R1) & which((df$RC == 'A' | df$RC == 'B'))] <- df2$R2[which(df$R1 == df2$R1) & which((df$RC == 'A' | df$RC == 'B'))]
df$R1[which(df$R1 == df2$R1) & which((df$RC != 'A' | df$RC != 'B'))] <- df2$R3[which(df$R1 == df2$R1) & which((df$RC != 'A' | df$RC != 'B'))]

但我因此失去了条件 1。

非常感谢您的帮助！

Answer 1

您可以在R1 上加入df 和df2，并使用case_when 申请条件：

library(dplyr)

df %>%
  left_join(df2, by = 'R1') %>%
  mutate(R2 = case_when(is.na(R2.y) ~ R2.x, 
                        RC %in% c('A', 'B') ~ R2.y, 
                        TRUE ~ R3)) %>%
  select(names(df))

#     R1 RC       R2
#1 15515  A      111
#2  5156  X 5156.11-
#3 65656  B      333
#4  1566  Z      666
#5  2857  A      886

Answer 2

使用ifelse 可能更容易做到这一点。注意 df 和 df2 有不同的 nrows 所以会有一个警告：

df$R2 <- ifelse(df$R1 != df2$R1, df$R2,
  ifelse(df$R1 == df2$R1 & (df$RC == "A" | df$RC == "B"), df2$R2,
    ifelse(df$R1 == df2$R1 & (df$RC != "A" | df$RC != "B"), df2$R3, "X")
  )
)

也许您可以省略最后一个 ifelse，如果没有满足您的条件，它将打印和“X”。

我也在运行 R 版本 3.6.1，如果我不使用 stringsAsFactors=FALSE，我会收到一条错误消息。