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
| > library(data.table)
data.table 1.8.7 For help type: help("data.table")
> heau <- data.table(jour = c("20000801", "20000801", "20000801", "20000802", "20000802", "20000803", "20000803", "20000803", "20000803", "20000804", "20000804", "20000804", "20000805", "20000805")
+ , heure = c("00:30", "07:42", "18:15", "01:12", "16:40", "00:51", "06:17", "13:32", "21:14", "02:15", "12:20", "22:10", "03:00", "23:00")
+ , hauteur = c(20.4, 25.2, 23.5, 27.1, 29.2, 30.5, 33.4, 31.3, 31.2, 33.2, 34.5, 36.2, 34.0, 32.5)
+ )
> heau
jour heure hauteur
1: 20000801 00:30 20.4
2: 20000801 07:42 25.2
3: 20000801 18:15 23.5
4: 20000802 01:12 27.1
5: 20000802 16:40 29.2
6: 20000803 00:51 30.5
7: 20000803 06:17 33.4
8: 20000803 13:32 31.3
9: 20000803 21:14 31.2
10: 20000804 02:15 33.2
11: 20000804 12:20 34.5
12: 20000804 22:10 36.2
13: 20000805 03:00 34.0
14: 20000805 23:00 32.5
> setkey(heau, jour)
> heau[, mean(hauteur), by = jour]
jour V1
1: 20000801 23.03333
2: 20000802 28.15000
3: 20000803 31.60000
4: 20000804 34.63333
5: 20000805 33.25000 |
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