基于标准在数据框中交换行

Question

我有一个data.table像这样。这是它的dput。

structure(list(Sepal.Length = c(5.4, 5.1, 5, 5, 4.9, 4.9, 4.7, 
4.6, 4.6, 4.4, 5.4, 5.1, 5, 5, 4.9, 4.9, 4.7, 4.6, 4.6, 4.4), 
    Sepal.Width = c(3.9, 3.5, 3.6, 3.4, 3.1, 3, 3.2, 3.4, 3.1, 
    2.9, 3.9, 3.5, 3.6, 3.4, 3.1, 3, 3.2, 3.4, 3.1, 2.9), Petal.Length = c(1.7, 
    1.4, 1.4, 1.5, 1.5, 1.4, 1.3, 1.4, 1.5, 1.4, 1.7, 1.4, 1.4, 
    1.5, 1.5, 1.4, 1.3, 1.4, 1.5, 1.4), Petal.Width = c(0.4, 
    0.2, 0.2, 0.2, 0.1, 0.2, 0.2, 0.3, 0.2, 0.2, 0.4, 0.2, 0.2, 
    0.2, 0.1, 0.2, 0.2, 0.3, 0.2, 0.2), Species = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L), .Label = c("setosa", "versicolor", "virginica" 
    ), class = "factor"), order = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 
    8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L)), .Names = c("Sepal.Length", 
"Sepal.Width", "Petal.Length", "Petal.Width", "Species", "order" 
), row.names = c(NA, -20L), class = c("data.table", "data.frame" 
), .internal.selfref = <pointer: 0x0000000000340788>) 

看起来像这样。这只是一个例子。

Sepal.Length Sepal.Width Petal.Length Petal.Width Species order 
1:   5.4   3.9   1.7   0.4 setosa  1 
2:   5.1   3.5   1.4   0.2 setosa  2 
3:   5.0   3.6   1.4   0.2 setosa  3 
4:   5.0   3.4   1.5   0.2 setosa  4 
5:   4.9   3.1   1.5   0.1 setosa  5 
6:   4.9   3.0   1.4   0.2 setosa  6 
7:   4.7   3.2   1.3   0.2 setosa  7 
8:   4.6   3.4   1.4   0.3 setosa  8 
9:   4.6   3.1   1.5   0.2 setosa  9 
10:   4.4   2.9   1.4   0.2 setosa 10 
11:   5.4   3.9   1.7   0.4 setosa  1 
12:   5.1   3.5   1.4   0.2 setosa  2 
13:   5.0   3.6   1.4   0.2 setosa  3 
14:   5.0   3.4   1.5   0.2 setosa  4 
15:   4.9   3.1   1.5   0.1 setosa  5 
16:   4.9   3.0   1.4   0.2 setosa  6 
17:   4.7   3.2   1.3   0.2 setosa  7 
18:   4.6   3.4   1.4   0.3 setosa  8 
19:   4.6   3.1   1.5   0.2 setosa  9 
20:   4.4   2.9   1.4   0.2 setosa 10 

我想什么是交换的行何柱order的值是1和2（保持柱order如交换，但剩余的列）。 所以，在上表中，第1行会被换行与2和行11将获得具有行12

交换所以输出如下：

Sepal.Length Sepal.Width Petal.Length Petal.Width Species order 
1:   5.1   3.5   1.4   0.2 setosa  1 
2:   5.4   3.9   1.7   0.4 setosa  2 
3:   5.0   3.6   1.4   0.2 setosa  3 
4:   5.0   3.4   1.5   0.2 setosa  4 
5:   4.9   3.1   1.5   0.1 setosa  5 
6:   4.9   3.0   1.4   0.2 setosa  6 
7:   4.7   3.2   1.3   0.2 setosa  7 
8:   4.6   3.4   1.4   0.3 setosa  8 
9:   4.6   3.1   1.5   0.2 setosa  9 
10:   4.4   2.9   1.4   0.2 setosa 10 
11:   5.1   3.5   1.4   0.2 setosa  1 
12:   5.4   3.9   1.7   0.4 setosa  2 
13:   5.0   3.6   1.4   0.2 setosa  3 
14:   5.0   3.4   1.5   0.2 setosa  4 
15:   4.9   3.1   1.5   0.1 setosa  5 
16:   4.9   3.0   1.4   0.2 setosa  6 
17:   4.7   3.2   1.3   0.2 setosa  7 
18:   4.6   3.4   1.4   0.3 setosa  8 
19:   4.6   3.1   1.5   0.2 setosa  9 
20:   4.4   2.9   1.4   0.2 setosa 10 
> 

请在上述公告输出行1和2以及原始表的行11和12已交换，保持列order原样。我如何以最有效的方式做到这一点，即快速而无需运行任何循环？

Answer 1

由于您要交换数据，因此在进行交换之前必须先创建副本。在下面的代码中，我创建了df1 data.frame，df的副本。在将它们插入原始df之前，我使用它来获取正确的行。我只挑选前五列离开df $订单。

df <-structure(list(Sepal.Length = c(5.4, 5.1, 5, 5, 4.9, 4.9, 4.7, 
4.6, 4.6, 4.4, 5.4, 5.1, 5, 5, 4.9, 4.9, 4.7, 4.6, 4.6, 4.4), 
    Sepal.Width = c(3.9, 3.5, 3.6, 3.4, 3.1, 3, 3.2, 3.4, 3.1, 
    2.9, 3.9, 3.5, 3.6, 3.4, 3.1, 3, 3.2, 3.4, 3.1, 2.9), Petal.Length = c(1.7, 
    1.4, 1.4, 1.5, 1.5, 1.4, 1.3, 1.4, 1.5, 1.4, 1.7, 1.4, 1.4, 
    1.5, 1.5, 1.4, 1.3, 1.4, 1.5, 1.4), Petal.Width = c(0.4, 
    0.2, 0.2, 0.2, 0.1, 0.2, 0.2, 0.3, 0.2, 0.2, 0.4, 0.2, 0.2, 
    0.2, 0.1, 0.2, 0.2, 0.3, 0.2, 0.2), Species = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L), .Label = c("setosa", "versicolor", "virginica" 
    ), class = "factor"), order = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 
    8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L)), .Names = c("Sepal.Length", 
"Sepal.Width", "Petal.Length", "Petal.Width", "Species", "order" 
), row.names = c(NA, -20L), class = c("data.table", "data.frame" 
)) 
df1 <-df 

df[df$order==2,1:5] <-df1[df1$order==1,1:5] 
df[df$order==1,1:5] <-df1[df1$order==2,1:5] 
> df 
    Sepal.Length Sepal.Width Petal.Length Petal.Width Species order 
1   5.1   3.5   1.4   0.2 setosa  1 
2   5.4   3.9   1.7   0.4 setosa  2 
3   5.0   3.6   1.4   0.2 setosa  3 
4   5.0   3.4   1.5   0.2 setosa  4 
5   4.9   3.1   1.5   0.1 setosa  5 
6   4.9   3.0   1.4   0.2 setosa  6 
7   4.7   3.2   1.3   0.2 setosa  7 
8   4.6   3.4   1.4   0.3 setosa  8 
9   4.6   3.1   1.5   0.2 setosa  9 
10   4.4   2.9   1.4   0.2 setosa 10 
11   5.1   3.5   1.4   0.2 setosa  1 
12   5.4   3.9   1.7   0.4 setosa  2 
13   5.0   3.6   1.4   0.2 setosa  3 
14   5.0   3.4   1.5   0.2 setosa  4 
15   4.9   3.1   1.5   0.1 setosa  5 
16   4.9   3.0   1.4   0.2 setosa  6 
17   4.7   3.2   1.3   0.2 setosa  7 
18   4.6   3.4   1.4   0.3 setosa  8 
19   4.6   3.1   1.5   0.2 setosa  9 
20   4.4   2.9   1.4   0.2 setosa 10