reshape package

> library(reshape)
> data(smiths)
> melt(smiths, id = c("subject", "time"), measured = c("age", "weight",
+     "height"))
     subject time variable value
1 John Smith    1      age 33.00
2 Mary Smith    1      age    NA
3 John Smith    1   weight 90.00
4 Mary Smith    1   weight    NA
5 John Smith    1   height  1.87
6 Mary Smith    1   height  1.54
> melt(smiths, id = c("subject", "time"))
     subject time variable value
1 John Smith    1      age 33.00
2 Mary Smith    1      age    NA
3 John Smith    1   weight 90.00
4 Mary Smith    1   weight    NA
5 John Smith    1   height  1.87
6 Mary Smith    1   height  1.54
> melt(smiths, id = 1:2)
     subject time variable value
1 John Smith    1      age 33.00
2 Mary Smith    1      age    NA
3 John Smith    1   weight 90.00
4 Mary Smith    1   weight    NA
5 John Smith    1   height  1.87
6 Mary Smith    1   height  1.54
> melt(smiths)
     subject variable value
1 John Smith     time  1.00
2 Mary Smith     time  1.00
3 John Smith      age 33.00
4 Mary Smith      age    NA
5 John Smith   weight 90.00
6 Mary Smith   weight    NA
7 John Smith   height  1.87
8 Mary Smith   height  1.54
> trial <- data.frame(id = factor(1:4), A1 = c(1, 2, 1, 2), A2 = c(2,
+     +1, 2, 1), B1 = c(3, 3, 3, 3))
> (trialm <- melt(trial))
   id variable value
1   1       A1     1
2   2       A1     2
3   3       A1     1
4   4       A1     2
5   1       A2     2
6   2       A2     1
7   3       A2     2
8   4       A2     1
9   1       B1     3
10  2       B1     3
11  3       B1     3
12  4       B1     3