问R使用开始/结束日期创建事件的时间表

EN

library(lubridate)
library(plyr)

#create data
df=data.frame(ID=c(1,2),
              StartDate=as.Date(c("2014-01-01","2014-02-03")),
              EndDate=as.Date(c("2014-04-15","2014-06-15")))

#create list with datetime intervals for events
event_interval_list=dlply(df,
                          "ID",
                          function(x) new_interval(x$StartDate,
                                                   x$EndDate,
                                                   tz="UTC")
                          )

#this is the eom day at 00:00:00
eom_day_vector_1=with_tz(as.POSIXct(seq(as.Date("2014-02-01"),
                                        as.Date("2014-07-01"),
                                        "month")-days(1)
                                    ),
                         "UTC")
#this is the eom day at 23:59:59
eom_day_vector_2=with_tz(as.POSIXct(seq(as.Date("2014-02-01"),
                                        as.Date("2014-07-01"),
                                        "month")-seconds(1)
                                    ),
                         "UTC")

#this is a list with all eom datetime ranges
eom_intervals=Map(function(x,y) interval(x,y),
                  eom_day_vector_1,
                  eom_day_vector_2)

#see whether there is an overlap of a given event interval...
#...with any eom datetime range
event_count=colSums(ldply(event_interval_list,function(x) !is.na(sapply(eom_intervals,function(y) intersect(x,y))))[-1])

#prepare result
res=data.frame(mth_yr=strftime(eom_day_vector_1,format="%m-%y"),
               event_count=event_count)
rownames(res)=NULL

#print result
res

# mth_yr event_count
#1 01-14           1
#2 02-14           2
#3 03-14           2
#4 04-14           1
#5 05-14           1
#6 06-14           0