Arrange two columns into a five variable dataframe
On 7/13/2012 8:37 PM, darnold wrote:
Hi, I hope that folks can give me some simple approaches to taking the data set below, which is accumulated in two columns called "long" and "group", then arrange the data is the "long" column into a data frame containing five variables: "Group 1", "Group 2", "Group 3", "Group 4", and "Group 5". I am hoping for a few different techniques which I can pass on to my students. Thanks David Arnold College of the Redwoods
dput(flies)
structure(list(long = c(40L, 37L, 44L, 47L, 47L, 47L, 68L, 47L,
54L, 61L, 71L, 75L, 89L, 58L, 59L, 62L, 79L, 96L, 58L, 62L, 70L,
72L, 74L, 96L, 75L, 46L, 42L, 65L, 46L, 58L, 42L, 48L, 58L, 50L,
80L, 63L, 65L, 70L, 70L, 72L, 97L, 46L, 56L, 70L, 70L, 72L, 76L,
90L, 76L, 92L, 21L, 40L, 44L, 54L, 36L, 40L, 56L, 60L, 48L, 53L,
60L, 60L, 65L, 68L, 60L, 81L, 81L, 48L, 48L, 56L, 68L, 75L, 81L,
48L, 68L, 35L, 37L, 49L, 46L, 63L, 39L, 46L, 56L, 63L, 65L, 56L,
65L, 70L, 63L, 65L, 70L, 77L, 81L, 86L, 70L, 70L, 77L, 77L, 81L,
77L, 16L, 19L, 19L, 32L, 33L, 33L, 30L, 42L, 42L, 33L, 26L, 30L,
40L, 54L, 34L, 34L, 47L, 47L, 42L, 47L, 54L, 54L, 56L, 60L, 44L
), group = structure(c(5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,
5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L), .Label = c("Group 5", "Group 4", "Group 3", "Group 2",
"Group 1"), class = "factor")), .Names = c("long", "group"), row.names =
c(NA,
-125L), class = "data.frame")
Generally I would recommend either the reshape function or the functions
in the reshape2 package. However, your data doesn't quite have what is
needed to use those. You are implicitly assuming that the first
occurring values in each group go together (should be in the same row),
the second ones, etc. The reshapes require an explicit indication of
which variables go together.
The unstack function will work for you and uses the same assumption.
> unstack(flies)
Group.5 Group.4 Group.3 Group.2 Group.1
1 16 35 21 46 40
2 19 37 40 42 37
3 19 49 44 65 44
4 32 46 54 46 47
5 33 63 36 58 47
6 33 39 40 42 47
7 30 46 56 48 68
8 42 56 60 58 47
9 42 63 48 50 54
10 33 65 53 80 61
11 26 56 60 63 71
12 30 65 60 65 75
13 40 70 65 70 89
14 54 63 68 70 58
15 34 65 60 72 59
16 34 70 81 97 62
17 47 77 81 46 79
18 47 81 48 56 96
19 42 86 48 70 58
20 47 70 56 70 62
21 54 70 68 72 70
22 54 77 75 76 72
23 56 77 81 90 74
24 60 81 48 76 96
25 44 77 68 92 75
Brian S. Diggs, PhD Senior Research Associate, Department of Surgery Oregon Health & Science University