[R] Order of boxplots

[li li]

Hi all,
  I have the following data "tmp" and I want to plot  boxplots for
each level of the factor "type" and the order the factor should be c,
b ,a. In other words, the boxplot corresponding to the level "c"
should be the first and so on.
Any suggestions?
   Li

> tmp
   result type
1     101    a
2     101    a
3     101    a
4     101    a
5     101    a
6     101    a
7     100    a
8     106    b
9      91    b
10     78    b
11     95    b
12    111    b
13     92    b
14     98    b
15    108    c
16    112    c
17     98    c
18    102    c
19     88    c
20     86    c
21     81    c