speciousfool - 7 months ago 52

R Question

I'd like to use R to make a series of boxplots which are sorted by median value. Suppose then I execute:

`boxplot(cost ~ type)`

This would give me some boxplots were cost is shown on the y axis and the type category is visible on the x-axis:

`----- -----`

| |

[ ] |

| [ ]

| |

----- -----

A B

However, what I'd like is the boxplot figures sorted from highest to lowest median value. My suspicion is that what I need to do is change the labels of the type (A or B) to numerically indicate which is the lowest and highest median value, but I wonder if there is a more clever way to solve the problem.

Answer

Check out `?reorder`

. The example seems to be what you want, but sorted in the opposite order. I changed `-count`

in the first line below to sort in the order you want.

```
bymedian <- with(InsectSprays, reorder(spray, -count, median))
boxplot(count ~ bymedian, data = InsectSprays,
xlab = "Type of spray", ylab = "Insect count",
main = "InsectSprays data", varwidth = TRUE,
col = "lightgray")
```