如果我在看到12月份的录入条目后立即阅读此权限,我们会更改学年。如果这是真的,那么下面的代码将起作用。
library(data.table)
library(lubridate)
df = data.frame(
date= structure(c(15461, 15553, 15675, 15826, 15918, 16040, 16191,
16405, 16556, 16648, 16770, 16922, 17014, 17136), class = "Date"),
n= 1:14
)
df$AcademicYear = cumsum(month(df$date) == 12)
setDT(df)
df[ , .(Sum = sum(n)), by = .(AcademicYear)]
AcademicYear Sum
1: 0 3
2: 1 12
3: 2 13
4: 3 27
5: 4 36
6: 5 14
编辑
的重构,你可以做这样的事情。它由AcademicYear寻找一个月,然后根据月份,它知道增加或减去一年并粘贴在一起。然后,该列只需要重新命名并如上所述进行求和。
df[ , "AcademicYear2" := ifelse(any(month(date) == 5), paste(year(date[month(date) == 5]) - 1,year(date[month(date) == 5]), sep = "/"),
ifelse(any(month(date) == 8), paste(year(date[month(date) == 8]) - 1,year(date[month(date) == 8]), sep = "/"),
paste(year(date[month(date) == 12]),year(date[month(date) == 12]) + 1, sep = "/"))), by = .(AcademicYear)]
> df
date n AcademicYear AcademicYear2
1: 2012-05-01 1 0 2011/2012
2: 2012-08-01 2 0 2011/2012
3: 2012-12-01 3 1 2012/2013
4: 2013-05-01 4 1 2012/2013
5: 2013-08-01 5 1 2012/2013
6: 2013-12-01 6 2 2013/2014
7: 2014-05-01 7 2 2013/2014
8: 2014-12-01 8 3 2014/2015
9: 2015-05-01 9 3 2014/2015
10: 2015-08-01 10 3 2014/2015
11: 2015-12-01 11 4 2015/2016
12: 2016-05-01 12 4 2015/2016
13: 2016-08-01 13 4 2015/2016
14: 2016-12-01 14 5 2016/2017
编辑2
决定把所有的代码放在一起。这应该让你找到你想要的最终结果。
library(data.table)
library(lubridate)
df = data.frame(
date= structure(c(15461, 15553, 15675, 15826, 15918, 16040, 16191,
16405, 16556, 16648, 16770, 16922, 17014, 17136), class = "Date"),
n= 1:14
)
setDT(df)
df$AcademicYear = cumsum(month(df$date) == 12)
df[ , "AcademicYear2" := ifelse(any(month(date) == 5), paste(year(date[month(date) == 5]) - 1,year(date[month(date) == 5]), sep = "/"),
ifelse(any(month(date) == 8), paste(year(date[month(date) == 8]) - 1,year(date[month(date) == 8]), sep = "/"),
paste(year(date[month(date) == 12]),year(date[month(date) == 12]) + 1, sep = "/"))), by = .(AcademicYear)]
df = df[ , .(Sum = sum(n)), by = .(AcademicYear = AcademicYear2)]
> df
AcademicYear Sum
1: 2011/2012 3
2: 2012/2013 12
3: 2013/2014 13
4: 2014/2015 27
5: 2015/2016 36
6: 2016/2017 14
我不明白yoru重构输出。 n在哪里?你不想每学年只有一行作最后的输出吗? – Kristofersen
此外,不应该是2016/2017的最大值?这与a.y的其余部分一致。 – Kristofersen
@Kristofersen谢谢,它似乎不够清楚哪些日期会对应于哪个学年,而伪输出只是表明这一点。另外,对于每个学年,是否有重复的行具有相同的'n'值而不是唯一的行,这与我一样。 – Dambo