我想计算自 event==1 以来经过的累计天数。是否可以使用 data.table 在 R 中执行此操作？
期望的结果:
id date event passed
1: A 2000-01-13 1 0
2: A 2000-01-18 0 5
3: A 2000-01-25 0 12
4: A 2000-01-31 1 0
5: B 2012-10-10 1 0
6: B 2012-10-11 0 1
7: B 2012-10-14 1 0
8: B 2012-10-15 0 1
9: C 2005-07-25 1 0
10: C 2005-07-31 0 6
df <- data.table(
id = c("A", "A", "A", "A",
"B", "B", "B", "B",
"C", "C"),
date = c("2000-01-13", "2000-01-18", "2000-01-25", "2000-01-31", # A
"2012-10-10", "2012-10-11", "2012-10-14", "2012-10-15", # B
"2005-07-25", "2005-07-31"), # C
event = c(1, 0, 0, 0,
0, 0, 1, 0,
1, 0)
)
编辑 (12/12/17):尝试使用@Psidom 的解决方案。
解决方案要求对 id 和 date 进行排序，这不是问题。但是注意到第 6 行:算作一天，尽管这应该是 0，因为该组尚未发生任何事件。
df2 <- df[sample(nrow(df)),]
df2 = df2[order(id, date)]
df2[, days_from_start := cumsum(c(0, diff(as.Date(date)))), by = .(id, cumsum(event))]
id date event days_from_start
1: A 2000-01-13 1 0
2: A 2000-01-18 0 5
3: A 2000-01-25 0 12
4: A 2000-01-31 0 18
5: B 2012-10-10 0 0
6: B 2012-10-11 0 1
7: B 2012-10-14 1 0
8: B 2012-10-15 0 1
9: C 2005-07-25 1 0
10: C 2005-07-31 0 6
最佳答案
如果event列仅包含 0和 1 ，您可以通过执行 cumsum(event) 创建一个组变量每当 event 时创建一个新组是1 ;然后按这个新变量分组，计算累计天数:
df[, days_from_start := cumsum(c(0, diff(as.Date(date)))), by = cumsum(event)]
# ^^^^^^^^^^^^^
df
# id date event days_from_start
# 1: A 2000-01-13 1 0
# 2: A 2000-01-18 0 5
# 3: A 2000-01-25 0 12
# 4: A 2000-01-31 1 0
# 5: B 2012-10-10 1 0
# 6: B 2012-10-11 0 1
# 7: B 2012-10-14 1 0
# 8: B 2012-10-15 0 1
# 9: C 2005-07-25 1 0
#10: C 2005-07-31 0 6
关于r - 自事件重复发生以来累计经过的天数(按组)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47786593/