在R中用data.table计算两个日期之间的累计和

Question

我有一个 data.table 形状如下：

date_from    date_until    value
2015-01-01   2015-01-03    100    
2015-01-02   2015-01-05     50
2015-01-02   2015-01-04     10
...

我想做的是：我想计算一年中每个日期的累计和。对于第一行，值 100 与从 2015-01-01 到 2015-01-03 的每一天相关。我想添加与特定日期相关的所有值。

所以，最后会有这样的data.table：

date        value
2015-01-01  100
2015-01-02  160
2015-01-03  160
2015-01-04   60
2015-01-05   50

data.table有什么简单的方法可以做到这一点吗？

Answer 1

dt[, .(date = seq(as.Date(date_from, '%Y-%m-%d'),
                  as.Date(date_until, '%Y-%m-%d'),
                  by='1 day'),
       value), by = 1:nrow(dt)][, sum(value), by = date]
#         date  V1
#1: 2015-01-01 100
#2: 2015-01-02 160
#3: 2015-01-03 160
#4: 2015-01-04  60
#5: 2015-01-05  50

另一个使用 foverlaps 的选项：

# convert to Date for ease
dt[, date_from := as.Date(date_from, '%Y-%m-%d')]
dt[, date_until := as.Date(date_until, '%Y-%m-%d')]

# all of the dates
alldates = dt[, do.call(seq, c(as.list(range(c(date_from, date_until))), by = '1 day'))]

# foverlaps to find the intersections
foverlaps(dt, data.table(date_from = alldates, date_until = alldates,
                         key = c('date_from', 'date_until')))[,
          sum(value), by = date_from]
#    date_from  V1
#1: 2015-01-01 100
#2: 2015-01-02 160
#3: 2015-01-03 160
#4: 2015-01-04  60
#5: 2015-01-05  50

在R中用data.table计算两个日期之间的累计和

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