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，但该组中的观察值顺序不正确。 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的值替换属于一个数据帧的列中的缺失值，同时匹配该“键”列的值。

这是我得到的。 希望有人能阐明这一点。 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 行是一个错误，您可以先使用左连接，然后使用ifelse()和coalesce()来获得您想要的结果。 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)