Question

我有一个如下所示的数据集：

first <- c(5:14)
second <- rep(c("a","b"),5)
c <- cbind(first, second)
c
    first second  
 [1,] "5"  "a"
 [2,] "6"  "b"
 [3,] "7"  "a"
 [4,] "8"  "b"
 [5,] "9"  "a"
 [6,] "10" "b"
 [7,] "11" "a"
 [8,] "12" "b"
 [9,] "13" "a"
[10,] "14" "b"

如您所见，有两个级别（a和b）
我想做一个摘要，显示每个级别中的值是什么类型。

a : 5,7,9,11,13
b : 6,8,10,12,14

Answer 1

OP创建了一个包含2列的矩阵。在应用找到here的众多解决方案之一之前，首先需要将其转换为data.frame或data.table。

# create matrix the way the OP has done it but using a different name 
# in order to avoid name conflicts with the c() function
first <- c(5:14)
second <- rep(c("a", "b"), 5)
mat <- cbind(first, second)

# one possible approach
library(data.table)
as.data.table(mat)[, .(first = toString(unique(first))), by = second]

   second            first
1:      a  5, 7, 9, 11, 13
2:      b 6, 8, 10, 12, 14

请注意，unique()的使用是出于OP的要求，即在每个级别显示 类型的 （强调我的）。

如何显示r中每个级别的所有值？

1 个答案: