问题
I have a dataframe as below. Originally it was just two columns/variables -"Timestamp" (which contains date and time) and "Actor". I broke down the "Timestamp" variable into "date" and "time" and then "time further down into "hours" and "mins". This then gives the following structure
dataf<-structure(list(hours = structure(c(3L, 4L, 4L, 3L, 3L, 3L, 6L,
6L, 6L, 6L, 6L, 2L, 2L, 2L, 2L, 5L, 5L, 5L, 1L, 1L, 2L, 2L), .Label = c("9",
"12", "14", "15", "16", "17"), class = "factor"), mins = structure(c(17L,
1L, 2L, 14L, 15L, 16L, 3L, 4L, 6L, 6L, 7L, 9L, 9L, 13L, 13L,
10L, 11L, 12L, 2L, 5L, 8L, 8L), .Label = c("00", "04", "08",
"09", "10", "12", "13", "18", "19", "20", "21", "22", "27", "39",
"51", "52", "59"), class = "factor"), date = structure(c(3L,
3L, 3L, 3L, 3L, 3L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 4L, 4L,
4L, 1L, 1L, 1L, 1L), .Label = c("4/28/2014", "5/18/2014", "5/2/2014",
"5/6/2014"), class = "factor"), time = structure(c(7L, 8L, 9L,
4L, 5L, 6L, 13L, 14L, 15L, 15L, 16L, 2L, 2L, 3L, 3L, 10L, 11L,
12L, 17L, 18L, 1L, 1L), .Label = c("12:18", "12:19", "12:27",
"14:39", "14:51", "14:52", "14:59", "15:00", "15:04", "16:20",
"16:21", "16:22", "17:08", "17:09", "17:12", "17:13", "9:04",
"9:10"), class = "factor"), Timestamp = structure(c(13L, 14L,
15L, 10L, 11L, 12L, 6L, 7L, 8L, 8L, 9L, 2L, 2L, 3L, 3L, 16L,
17L, 18L, 4L, 5L, 1L, 1L), .Label = c("4/28/2014 12:18", "4/28/2014 12:19",
"4/28/2014 12:27", "4/28/2014 9:04", "4/28/2014 9:10", "5/18/2014 17:08",
"5/18/2014 17:09", "5/18/2014 17:12", "5/18/2014 17:13", "5/2/2014 14:39",
"5/2/2014 14:51", "5/2/2014 14:52", "5/2/2014 14:59", "5/2/2014 15:00",
"5/2/2014 15:04", "5/6/2014 16:20", "5/6/2014 16:21", "5/6/2014 16:22"
), class = "factor"), Actor = c(7L, 7L, 7L, 7L, 7L, 7L, 5L, 5L,
2L, 12L, 2L, 7L, 7L, 7L, 7L, 10L, 10L, 10L, 7L, 10L, 7L, 7L)), .Names = c("hours",
"mins", "date", "time", "Timestamp", "Actor"), row.names = c(NA,
-22L), class = "data.frame")
The reason for breaking the timestamp and time variables down into separate variables was because in my real data I have had a lot of problems sorting by data and/or time. Breaking these variables down into smaller chunks has made it much easier to sort.
What I would like to do now is create a new variable called "Rank", which would return a '1' for the earliest event in the dataframe (which would be the observation at 9.04am on the 28th April 2014), then a '2' for the next observation in date/time order and so on.
Sorting the dataframe appears to be relatively trivial:
dataf<-dataf[order(as.Date(dataf$date, format="%m/%d/%Y"), dataf$hours, dataf$mins),]
This does the job. But what I am struggling with is now to assign ranks.
I tried this, because I have used 'ave' in combination with FUN=rank to rank integers, but what it produces is laughably wrong:
dataf$rank <- ave((dataf[order(as.Date(dataf$date, format="%m/%d/%Y"), dataf$hours, dataf$mins),]),FUN=rank )
any help appreciated
回答1:
I do not share your aversion to datetime objects, which makes this all much simpler:
dataf$ts <- strptime(as.character(dataf$Timestamp),'%m/%d/%Y %H:%M')
dataf <- dataf[order(dataf$ts),]
dataf$ts_rank <- rank(dataf$ts,ties.method = "min")
dataf
## hours mins date time Timestamp Actor ts ts_rank
## 19 9 04 4/28/2014 9:04 4/28/2014 9:04 7 2014-04-28 09:04:00 1
## 20 9 10 4/28/2014 9:10 4/28/2014 9:10 10 2014-04-28 09:10:00 2
## 21 12 18 4/28/2014 12:18 4/28/2014 12:18 7 2014-04-28 12:18:00 3
## 22 12 18 4/28/2014 12:18 4/28/2014 12:18 7 2014-04-28 12:18:00 3
## 12 12 19 4/28/2014 12:19 4/28/2014 12:19 7 2014-04-28 12:19:00 5
## 13 12 19 4/28/2014 12:19 4/28/2014 12:19 7 2014-04-28 12:19:00 5
## 14 12 27 4/28/2014 12:27 4/28/2014 12:27 7 2014-04-28 12:27:00 7
## 15 12 27 4/28/2014 12:27 4/28/2014 12:27 7 2014-04-28 12:27:00 7
## 4 14 39 5/2/2014 14:39 5/2/2014 14:39 7 2014-05-02 14:39:00 9
## 5 14 51 5/2/2014 14:51 5/2/2014 14:51 7 2014-05-02 14:51:00 10
## 6 14 52 5/2/2014 14:52 5/2/2014 14:52 7 2014-05-02 14:52:00 11
## 1 14 59 5/2/2014 14:59 5/2/2014 14:59 7 2014-05-02 14:59:00 12
## 2 15 00 5/2/2014 15:00 5/2/2014 15:00 7 2014-05-02 15:00:00 13
## 3 15 04 5/2/2014 15:04 5/2/2014 15:04 7 2014-05-02 15:04:00 14
## 16 16 20 5/6/2014 16:20 5/6/2014 16:20 10 2014-05-06 16:20:00 15
## 17 16 21 5/6/2014 16:21 5/6/2014 16:21 10 2014-05-06 16:21:00 16
## 18 16 22 5/6/2014 16:22 5/6/2014 16:22 10 2014-05-06 16:22:00 17
## 7 17 08 5/18/2014 17:08 5/18/2014 17:08 5 2014-05-18 17:08:00 18
## 8 17 09 5/18/2014 17:09 5/18/2014 17:09 5 2014-05-18 17:09:00 19
## 9 17 12 5/18/2014 17:12 5/18/2014 17:12 2 2014-05-18 17:12:00 20
## 10 17 12 5/18/2014 17:12 5/18/2014 17:12 12 2014-05-18 17:12:00 20
## 11 17 13 5/18/2014 17:13 5/18/2014 17:13 2 2014-05-18 17:13:00 22
来源：https://stackoverflow.com/questions/23792890/sorting-and-ranking-a-dataframe-by-date-and-time-in-r