聚合并删除某些行的重复项答案

【问题标题】：aggregate and removes duplicates for some rows聚合并删除某些行的重复项
【发布时间】：2021-05-05 09:06:13
【问题描述】：

我有一个类似的数据集

df <- data.frame(id = c("a","a","b","b","c","d","e","f"),
                 val = c(1,2,3,4,5,6,7,8),
                 extracol = c("x",NA,"y","z","t","v","u","p"))

  id val extracol
1  a   1        x
2  a   2     <NA>
3  b   3        y
4  b   4        z
5  c   5        t
6  d   6        v
7  e   7        u
8  f   8        p

我想根据列 id 对值求和（并聚合），但仅针对“a”。所以我想得到类似的东西：

  id val extracol
1  a   3        x
2  b   3        y
3  b   4        z
4  c   5        t
5  d   6        v
6  e   7        u
7  f   8        p

我真的不在乎我是否在 extracol 中得到“x”或 NA。有什么建议吗？

【问题讨论】：

标签： r duplicates aggregate

【解决方案1】：

这可行：

library(dplyr)
df <- data.frame(id = c("a","a","b","b","c","d","e","f"),
                 val = c(1,2,3,4,5,6,7,8),
                 extracol = c("x",NA,"y","z","t","v","u","p"))

# keep only a
a = df%>% filter(id == "a")

# aggregate a
a_agg= a %>% group_by(id) %>% summarise(val = sum(val), extracol = first(extracol))

# drop a
df = df %>% filter(id != "a")

# append a
df = rbind(df, a_agg)

df

   id val extracol
1  b   3        y
2  b   4        z
3  c   5        t
4  d   6        v
5  e   7        u
6  f   8        p
7  a   3        x

【讨论】：

如果只有一个 id 值，其实不需要按 id 分组
真的！但如果应该处理更多值而不是a 可能会有用

【解决方案2】：

基本 R 选项

with(
  df,
  rbind(
    data.frame(
      id = "a",
      val = sum(val[id == "a"]),
      extracol = na.omit(extracol[id == "a"])
    ),
    df[id != "a", ]
  )
)

给予

  id val extracol
1  a   3        x
3  b   3        y
4  b   4        z
5  c   5        t
6  d   6        v
7  e   7        u
8  f   8        p

【讨论】：