Christopher DuBois - 9 months ago 51

R Question

I want to sort a

`data.frame`

`data.frame`

`z`

`b`

`dd <- data.frame(b = factor(c("Hi", "Med", "Hi", "Low"),`

levels = c("Low", "Med", "Hi"), ordered = TRUE),

x = c("A", "D", "A", "C"), y = c(8, 3, 9, 9),

z = c(1, 1, 1, 2))

dd

b x y z

1 Hi A 8 1

2 Med D 3 1

3 Hi A 9 1

4 Low C 9 2

Answer

You can use the `order()`

function directly without resorting to add-on tools -- see this simpler answer which uses a trick right from the top of the `example(order)`

code:

```
R> dd[with(dd, order(-z, b)), ]
b x y z
4 Low C 9 2
2 Med D 3 1
1 Hi A 8 1
3 Hi A 9 1
```

*Edit some 2+ years later:* It was just asked how to do this by column index. The answer is to simply pass the desired sorting column(s) to the `order()`

function:

```
R> dd[ order(-dd[,4], dd[,1]), ]
b x y z
4 Low C 9 2
2 Med D 3 1
1 Hi A 8 1
3 Hi A 9 1
R>
```

rather than using the name of the column (and `with()`

for easier/more direct access).