我有两个数据框。其中之一（df1）概述了在特定区域中检测到鱼时的情况。另一个总结了在这个特定区域中有潜水者的时期。举个例子：
datetime<- c("2016-08-01 06:00:02","2016-08-01 09:31:27","2016-08-01 13:34:02","2016-08-01 16:45:15","2016-08-02 09:07:12","2016-08-02 11:25:02","2016-08-02 17:25:02","2016-08-02 21:50:00")
df1<-data.frame(datetime)
df1$datetime<- as.POSIXct(df1$datetime, format = "%Y-%m-%d %H:%M:%S")
start<- c("2016-08-01 07:00:00","2016-08-01 08:30:00","2016-08-01 10:30:00","2016-08-01 16:00:00","2016-08-02 10:00:00","2016-08-02 16:00:00")
end<- c("2016-08-01 08:30:00","2016-08-01 10:00:00","2016-08-01 12:00:00","2016-08-01 17:30:00","2016-08-02 11:30:00","2016-08-02 17:30:00")
divers<-c(6,2,8,12,8,7)
df2<-data.frame(start,end,divers)
df2$start<- as.POSIXct(df2$start, format = "%Y-%m-%d %H:%M:%S")
df2$end<- as.POSIXct(df2$end, format = "%Y-%m-%d %H:%M:%S")
df1
datetime
1 2016-08-01 06:00:02
2 2016-08-01 09:31:27
3 2016-08-01 13:34:02
4 2016-08-01 16:45:15
5 2016-08-02 09:07:12
6 2016-08-02 11:25:02
7 2016-08-02 17:25:02
8 2016-08-02 21:50:00
df2 # Notice there are four periods with divers on 2016-08-01 and only two on 2016-08-02.
start end divers
1 2016-08-01 07:00:00 2016-08-01 08:30:00 6
2 2016-08-01 08:30:00 2016-08-01 10:00:00 2
3 2016-08-01 10:30:00 2016-08-01 12:00:00 8
4 2016-08-01 16:00:00 2016-08-01 17:30:00 12
5 2016-08-02 10:00:00 2016-08-02 11:30:00 8
6 2016-08-02 16:00:00 2016-08-02 17:30:00 7
我想在数据框df1的新列中添加有关潜水员存在的信息。在df1的这个新列中，我们将其称为“潜水员”，我想显示在检测到鱼时存在的潜水员的数量。如果根据df1提示存在鱼，则根据df2提示该区域中没有潜水员，则将“ df1 $ divers”加0。如果根据df1出现鱼，则有5个潜水员，则将5个添加到“ df1 $ divers”。作为我期望的示例：
datetime<- c("2016-08-01 06:00:02","2016-08-01 09:31:27","2016-08-01 13:34:02","2016-08-01 16:45:15","2016-08-02 09:07:12","2016-08-02 11:25:02","2016-08-02 17:25:02","2016-08-02 21:50:00")
divers<- c(0,2,0,12,0,8,7,0)
result<-data.frame(datetime,divers)
result$datetime<- as.POSIXct(result$datetime, format = "%Y-%m-%d %H:%M:%S")
result
datetime divers
1 2016-08-01 06:00:02 0
2 2016-08-01 09:31:27 2
3 2016-08-01 13:34:02 0
4 2016-08-01 16:45:15 12
5 2016-08-02 09:07:12 0
6 2016-08-02 11:25:02 8
7 2016-08-02 17:25:02 7
8 2016-08-02 21:50:00 0
使用基础R，我们可以使用sapply在datetime列df1，并找出哪些而是介于两者之间的时间start和end时间df2，得到相应的divers与sum他们。
df1$divers <- sapply(df1$datetime, function(x)
sum(with(df2, divers[x >= start & x <= end])))
df1
# datetime divers
#1 2016-08-01 06:00:02 0
#2 2016-08-01 09:31:27 2
#3 2016-08-01 13:34:02 0
#4 2016-08-01 16:45:15 12
#5 2016-08-02 09:07:12 0
#6 2016-08-02 11:25:02 8
#7 2016-08-02 17:25:02 7
#8 2016-08-02 21:50:00 0
我们可以使用dplyr/purrr替代与map_dbl
library(dplyr)
library(purrr)
df1 %>%
mutate(divers = map_dbl(datetime, ~ sum(with(df2, divers[. >= start & . <= end]))))
在OP的示例中sum，divers由于时间start和end时间上没有重叠，因此没有必要这样做，但是如果存在重叠，则最好sum在该时间段内添加所有潜水者。
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我来说两句