计算R中的累积时间 [英] Calculating cumulative time in R

问题描述

我有一个看起来像这样的数据框:

I have a dataframe that looks like this:

     POI   LOCAL.DATETIME
1    1     2017-07-11 15:02:13
2    1     2017-07-11 15:20:28
3    2     2017-07-11 15:20:31
4    2     2017-07-11 15:21:13
5    3     2017-07-11 15:21:18
6    3     2017-07-11 15:21:21
7    2     2017-07-11 15:21:25
8    2     2017-07-11 15:21:59
9    1     2017-07-11 15:22:02
10   1     2017-07-11 15:22:05

我希望能够计算(可能使用lubridate)在每个POI上花费的累积时间，并将它们组合成一个看起来像这样的表:

I want to be able to calculate (probably with lubridate) the cumulative time spent at each POI and combine them into a table that looks something like this:

     POI   TOTAL.TIME
1    1     00:18:18
2    2     00:01:11
3    3     00:00:03

此外，我不确定如何处理POI之间的时间，例如第2行和第3行之间的3秒.我想也许我需要计算从第1行到第3行的时间，而不是从第1行到第2行的时间.

Also, I am not sure how to deal with the time between POIs, like the 3 seconds between rows 2 and 3. I think maybe I need to calculate the time from row 1 to row 3 instead of row 1 to row 2.

推荐答案

要获取每个组时段中的总时间，首先需要创建一个组索引.我正在使用data.table中的rleid，然后，可以计算出每个组中花费的总时间，然后使用sum通过初始POI进行汇总.

To get the total time in each group's periods, you first need to create a group index. I'm using rleid from data.table You can then, calculate the total time spent in each of these groups, and then summarise by the initial POI using sum.

df <- read.table(text="     POI   LOCAL.DATETIME
1     '2017-07-11 15:02:13'
1     '2017-07-11 15:20:28'
2     '2017-07-11 15:20:31'
2     '2017-07-11 15:21:13'
3     '2017-07-11 15:21:18'
3     '2017-07-11 15:21:21'
2     '2017-07-11 15:21:25'
2     '2017-07-11 15:21:59'
1     '2017-07-11 15:22:02'
1     '2017-07-11 15:22:05'",
                 header=TRUE,stringsAsFactors=FALSE)
df$LOCAL.DATETIME <- as.POSIXct(df$LOCAL.DATETIME)

library(dplyr)
df%>%
  mutate(grp=data.table::rleid(POI))%>%
  group_by(grp)%>%
  summarise(POI=max(POI),TOTAL.TIME=difftime(max(LOCAL.DATETIME),
                                     min(LOCAL.DATETIME),units="secs"))%>%
  group_by(POI)%>%
  summarise(TOTAL.TIME=sum(TOTAL.TIME))

# A tibble: 3 × 2
    POI TOTAL.TIME
  <int>     <time>
1     1  1098 secs
2     2    76 secs
3     3     3 secs

要获取分钟和秒钟，可以使用lubridate中的as.period:

To get minute and seconds, you can use as.period from lubridate:

library(lubridate)
df%>%
  mutate(grp=data.table::rleid(POI))%>%
  group_by(grp)%>%
  summarise(POI=max(POI),TOTAL.TIME=difftime(max(LOCAL.DATETIME),
                                    min(LOCAL.DATETIME),units="secs"))%>%
  group_by(POI)%>%
  summarise(TOTAL.TIME=sum(TOTAL.TIME))%>%
  mutate(TOTAL.TIME =as.period((TOTAL.TIME), unit = "sec"))

    POI   TOTAL.TIME
  <int> <S4: Period>
1     1      18M 18S
2     2       1M 16S
3     3           3S

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