hadley wickham wrote:
On Fri, Jan 30, 2009 at 5:57 PM, Neil Stewart
<neil.stew...@warwick.ac.uk> wrote:
I have a data frame in wide format that I'd like to convert to long format.
For example, in wide format I have:
id A1B1 A1B2 A2B1 A2B2
1 1 400 475 420 510
2 2 390 500 470 472
3 3 428 512 555 610
4 4 703 787 801 822
5 5 611 634 721 705
6 6 543 522 612 788
7 7 411 488 506 623
8 8 654 644 711 795
A is one repeated-measures variable with levels 1 and 2. B is a second
repeated-measures variable also with levels 1 and 2. I'd like to end up
with:
id A B value
1 1 1 1 400
2 2 1 1 390
3 3 1 1 428
4 4 1 1 703
5 5 1 1 611
6 6 1 1 543
7 7 1 1 411
8 8 1 1 654
9 1 1 2 475
10 2 1 2 500
11 3 1 2 512
12 4 1 2 787
13 5 1 2 634
14 6 1 2 522
15 7 1 2 488
16 8 1 2 644
17 1 2 1 420
18 2 2 1 470
19 3 2 1 555
20 4 2 1 801
21 5 2 1 721
22 6 2 1 612
23 7 2 1 506
24 8 2 1 711
25 1 2 2 510
26 2 2 2 472
27 3 2 2 610
28 4 2 2 822
29 5 2 2 705
30 6 2 2 788
31 7 2 2 623
32 8 2 2 795
I've been working with reshape and with the reshape package, but with no
success for the two-time-variable case. Can anyone help please?
If you're using melt from the reshape package, once you've melted the
data, you'll need to do something like:
m$a <- as.numeric(substr(m$variable, 1, 1))
m$b <- as.numeric(substr(m$variable, 3, 3))
m$variable <- NULL
Also, things like this should work (here using stock reshape):
> xx <- reshape(x, direction="long", varying=2:5, v.names="val")
> cbind(xx, expand.grid(B=1:2,A=1:2)[xx$time,])
id time val B A
1.1 1 1 400 1 1
2.1 2 1 390 1 1
3.1 3 1 428 1 1
4.1 4 1 703 1 1
5.1 5 1 611 1 1
6.1 6 1 543 1 1
7.1 7 1 411 1 1
8.1 8 1 654 1 1
1.2 1 2 475 2 1
2.2 2 2 500 2 1
3.2 3 2 512 2 1
4.2 4 2 787 2 1
5.2 5 2 634 2 1
...
Once you got your mind wrapped around it, the pattern might be easier to
generalize to more complex within-subject designs.
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907
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