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我想为数据框中的每个组添加一个排序的ID(按日期)。我能做到这一点使用dplyr(R - add column that counts sequentially within groups but repeats for duplicates):使用rleid为每个组添加按日期排序的ID
# Example data
date <- rep(c("2016-10-06 11:56:00","2016-10-05 11:56:00","2016-10-05 11:56:00","2016-10-07 11:56:00"),2)
date <- as.POSIXct(date)
group <- c(rep("A",4), rep("B",4))
df <- data.frame(group, date)
# dplyr - dense_rank
df2 <- df %>% group_by(group) %>%
mutate(m.test=dense_rank(date))
group date m.test
<fctr> <dttm> <int>
1 A 2016-10-06 11:56:00 2
2 A 2016-10-05 11:56:00 1
3 A 2016-10-05 11:56:00 1
4 A 2016-10-07 11:56:00 3
5 B 2016-10-06 11:56:00 2
6 B 2016-10-05 11:56:00 1
7 B 2016-10-05 11:56:00 1
8 B 2016-10-07 11:56:00 3
所以我的新列m.test
每个group
通过date
行列。如果我使用rleid
和data.table
,它似乎并没有工作(05/10 06/10后排名):
df3 <- setDT(df)[, m.test := rleid(date), by = group]
group date m.test
1: A 2016-10-06 11:56:00 1
2: A 2016-10-05 11:56:00 2
3: A 2016-10-05 11:56:00 2
4: A 2016-10-07 11:56:00 3
5: B 2016-10-06 11:56:00 1
6: B 2016-10-05 11:56:00 2
7: B 2016-10-05 11:56:00 2
8: B 2016-10-07 11:56:00 3
上午我得到的语法错了吗?
的'dplyr的'DENSE_RANK(...)的data.table'相当于''是弗兰克(.. 。,ties.method =“dense”)',afaik –
谢谢。我从最初问我这个问题的答案变得困惑(http://stackoverflow.com/questions/37008864/add-id-by-group-which-resets-to-1-in-r)。我认为在这种情况下rleid不适用于日期。 – Pete900
你想发布一个答案。 – Pete900