R 按disticnt行值将多行合并到单个列中

使用R尝试合并原始矩阵，以基于行值的值生成矩阵

例：

发件人：

致：

---

我们可以使用

split

split(df1[,2], df1[,1])
#$a1
#[1] 10 20 40

#$a2
#[1] 45 50

#$a3
#[1] 40

#$a4
#[1] 45 60

---

要创建

向量的
列表
或使用
聚合
：

aggregate(df$X2~df$X1, df, rbind)

  # df$X1      df$X2
# 1    a1 10, 20, 40
# 2    a2     45, 50
# 3    a3         40
# 4    a4     45, 60

数据

df <- structure(list(X1 = structure(c(1L, 1L, 1L, 2L, 2L, 3L, 4L, 4L
), .Label = c("a1", "a2", "a3", "a4"), class = "factor"), X2 = c(10L, 
20L, 40L, 45L, 50L, 40L, 45L, 60L)), .Names = c("X1", "X2"), class = 
"data.frame", row.names = c(NA, 
    -8L))

df
aggregate(df$X2~df$X1, df, rbind)

  # df$X1      df$X2
# 1    a1 10, 20, 40
# 2    a2     45, 50
# 3    a3         40
# 4    a4     45, 60

df <- structure(list(X1 = structure(c(1L, 1L, 1L, 2L, 2L, 3L, 4L, 4L
), .Label = c("a1", "a2", "a3", "a4"), class = "factor"), X2 = c(10L, 
20L, 40L, 45L, 50L, 40L, 45L, 60L)), .Names = c("X1", "X2"), class = 
"data.frame", row.names = c(NA, 
    -8L))