library(data.table)
df <- data.table(col1 = c('B', 'A', 'A', 'B', 'B', 'B'), col2 = c("2015-03-06 01:37:57", "2015-03-06 01:39:57", "2015-03-06 01:45:28", "2015-03-06 02:31:44", "2015-03-06 03:55:45", "2015-03-06 04:01:40"))
对于每一行,我想计算具有相同“col1”值的行数以及该行时间之前过去 10 分钟的窗口内的时间(包括)
我运行下一个代码:
df$col2 <- as_datetime(df$col2)
window = 10L
(counts = setDT(df)[.(t1=col2-window*60L, t2=col2), on=.((col2>=t1) & (col2<=t2)),
.(counts=.N), by=col1]$counts)
df[, counts := counts]
并得到下一个错误:
Error in `[.data.table`(setDT(df), .(t1 = col2 - window * 60L, t2 = col2), : Column(s) [(col2] not found in x
我想要如下结果:
col1 col2 counts
B 2015-03-06 01:37:57 1
A 2015-03-06 01:39:57 1
A 2015-03-06 01:45:28 2
B 2015-03-06 02:31:44 1
B 2015-03-06 03:55:45 1
B 2015-03-06 04:01:40 2