Nice example of converting wide to tall data with tidyr

Nice example.

> x <- structure(c(1961, 1961, 1961, 1961, 1, 1, 1, 1, 1, 2, 3
+         , 4, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
+         , 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27
+         , 28, 29, 30, 31, 32, 33, 34, 35, 36)
+     , .Dim = c(4L, 12L)
+     , .Dimnames = list(NULL, c("year", "month", "day", "A", "B", "C"
+         , "D", "E", "F", "G", "H", "I"))
+     )
> xdf <- as.data.frame(x)
> xdf
  year month day A B  C  D  E  F  G  H  I
1 1961     1   1 1 5  9 13 17 21 25 29 33
2 1961     1   2 2 6 10 14 18 22 26 30 34
3 1961     1   3 3 7 11 15 19 23 27 31 35
4 1961     1   4 4 8 12 16 20 24 28 32 36
> require(tidyr)
> require(dplyr)
> xdf %>% gather(station, discharge, -year, -month, -day)
   year month day station discharge
1  1961     1   1       A         1
2  1961     1   2       A         2
3  1961     1   3       A         3
4  1961     1   4       A         4
5  1961     1   1       B         5
6  1961     1   2       B         6
7  1961     1   3       B         7
8  1961     1   4       B         8
9  1961     1   1       C         9
10 1961     1   2       C        10
11 1961     1   3       C        11
12 1961     1   4       C        12
13 1961     1   1       D        13
14 1961     1   2       D        14
15 1961     1   3       D        15
16 1961     1   4       D        16
17 1961     1   1       E        17