On Dec 23, 2011, at 5:58 PM, David Winsemius wrote:
On Dec 23, 2011, at 2:58 PM, Kaiyin Zhong wrote:
library(reshape2)
x = melt(airquality, id=c('month', 'day'))
With reshape I can cast with multiple functions:
library(reshape)
cast(x, month+variable~., c(mean,sd))
month variable mean sd
1 5 ozone 23.615385 22.224449
2 5 solar.r 181.296296 115.075499
3 5 wind 11.622581 3.531450
4 5 temp 65.548387 6.854870
5 6 ozone 29.444444 18.207904
6 6 solar.r 190.166667 92.882975
7 6 wind 10.266667 3.769234
8 6 temp 79.100000 6.598589
9 7 ozone 59.115385 31.635837
10 7 solar.r 216.483871 80.568344
11 7 wind 8.941935 3.035981
12 7 temp 83.903226 4.315513
13 8 ozone 59.961538 39.681210
14 8 solar.r 171.857143 76.834943
15 8 wind 8.793548 3.225930
16 8 temp 83.967742 6.585256
17 9 ozone 31.448276 24.141822
18 9 solar.r 167.433333 79.118280
19 9 wind 10.180000 3.461254
20 9 temp 76.900000 8.355671
Is there a way to do the same job with reshape2?
Have you looked at the .summarise argument to dcast? That seems to
deliver the same sort of results one gets with base::aggregate.
Actually I see after looking at examples on the plyr-reshape-
googlegroups group that it is not '.summarise' but rather 'summarise'.
Unfortunately there are no links in the help pages that seem to
describe its proper use ... a not uncommon failing for that package in
my experience.
--
David Winsemius, MD
West Hartford, CT
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