匹配变量时的条件替换

Question

我想替换特定子组中观察值的 NA 值，但该组中的观察顺序未正确排序。所以我想知道是否存在一些dplyr 或plyr 命令允许我使用来自另一个数据帧的同一列中的值替换属于一个数据帧的列中的缺失值，同时匹配该“键”的值"列。

这就是我得到的。希望有人可以阐明这一点。谢谢。

## data frame that contains missing values in "diff" column

df <- data.frame(type = c(1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3), 
diff = c(0.1, 0.3, NA, NA, NA, NA, NA, 0.2, 0.7, NA, 0.5, NA), 
name = c("A", "B", "C", "D", "E", "A", "B", "C", "F", "A", "B", "C"))

## replace with values from this smaller data frame

df2 <- data.frame(diff_rep = c(0.3, 0.2, 0.4), name = c("A", "B", "C"))

## replace using ifelse
df$diff <- ifelse(is.na(df$diff) & (df$type == 2), df2$diff_rep , df$diff)

df

   type diff name
1     1  0.1    A
2     1  0.3    B
3     1   NA    C
4     2  0.3    D
5     2  0.2    E
6     2  0.4    A
7     2  0.3    B
8     2  0.2    C
9     2  0.7    F
10    3   NA    A
11    3  0.5    B
12    3   NA    C

## desired output

   type diff name
1     1  0.1    A
2     1  0.3    B
3     1   NA    C
4     2   NA    D
5     2   NA    E
6     2  0.3    A
7     2  0.2    B
8     2  0.4    C
9     2  0.7    F
10    3   NA    A
11    3  0.5    B
12    3   NA    C

Answer 1

假设第 9 行是错误的，您可以先使用左连接，然后使用 ifelse() 和 coalesce() 来获得所需的结果。 coalesce() 返回第一个非缺失值

left_join(df, df2, by = "name") %>% 
  mutate(diff_wanted = if_else(type == 2,
                               coalesce(diff, diff_rep),
                               diff),
         diff_wanted = ifelse(name %in% df2$name,
                              diff_wanted,
                              NA)) %>% 
  select(type, diff_wanted, name)