合并多列中具有相同值的行

Question

我有一个包含多行多列（13232 行和 18 列）的 excel 文件。最后一列给出了一些价值。我想要做的是 - 找到除最后一个之外具有相同列详细信息的行并将它们的最后一列值相加。 例如： 如果输入是

+---------+---------+---------+---------+
| Column1 | Column2 | Column3 | Column4 |
+---------+---------+---------+---------+
| ABC     | DEF     | GHI     |       5 |
| XYZ     | PQR     | LMN     |       4 |
| ABC     | DEF     | GHI     |      11 |
| Test1   | Test2   | Test3   |      12 |
| XYZ     | PQR     | LMN     |      54 |
+---------+---------+---------+---------+

那么输出应该是

+---------+---------+---------+---------+
| Column1 | Column2 | Column3 | Column4 |
+---------+---------+---------+---------+
| ABC     | DEF     | GHI     |      16 |
| XYZ     | PQR     | LMN     |      58 |
| Test1   | Test2   | Test3   |      12 |
+---------+---------+---------+---------+

如何在 R 中实现这一点？

Answer 1

你可以从base R使用aggregate

 aggregate(Column4~., df1, FUN=sum)
 #    Column1 Column2 Column3 Column4
 #1     ABC     DEF     GHI      16
 #2     XYZ     PQR     LMN      58
 #3   Test1   Test2   Test3      12

或者

 library(data.table)
 setDT(df1)[, list(Column4=sum(Column4)), by = c(names(df1)[1:3])]
 #     Column1 Column2 Column3 Column4
 #1:     ABC     DEF     GHI      16
 #2:     XYZ     PQR     LMN      58
 #3:   Test1   Test2   Test3      12

或者

 library(sqldf)
 sqldf('select Column1, Column2, Column3,
          sum(Column4) as Column4
          from df1 
          group by Column1, Column2, Column3')
 #   Column1 Column2 Column3 Column4
 #1     ABC     DEF     GHI      16
 #2   Test1   Test2   Test3      12
 #3     XYZ     PQR     LMN      58

或者

library(dplyr)
df1 %>% group_by(Column1, Column2, Column3) %>%
  summarize(Column4 = sum(Column4))
# Source: local data frame [3 x 4]
# Groups: Column1, Column2

#   Column1 Column2 Column3 Column4
# 1     ABC     DEF     GHI      16
# 2   Test1   Test2   Test3      12
# 3     XYZ     PQR     LMN      58

---

可重现的数据：

df1 <-
structure(list(Column1 = structure(c(1L, 3L, 1L, 2L, 3L), .Label = c("ABC", 
"Test1", "XYZ"), class = "factor"), Column2 = structure(c(1L, 
2L, 1L, 3L, 2L), .Label = c("DEF", "PQR", "Test2"), class = "factor"), 
    Column3 = structure(c(1L, 2L, 1L, 3L, 2L), .Label = c("GHI", 
    "LMN", "Test3"), class = "factor"), Column4 = c(5L, 4L, 11L, 
    12L, 54L)), .Names = c("Column1", "Column2", "Column3", "Column4"
), class = "data.frame", row.names = c(NA, -5L))