R-计算连续日期的最大数目 [英] R - count maximum number of consecutive dates

问题描述

我正在尝试按组计算连续日期的最大长度，但我一直在努力获取。我已经包含了类似布局的代码的代码。

I'm trying to count the maximum length of consecutive dates by group, but I'm struggling to get it. I have included code for a similarly laid-out tibble to mine.

library(dplyr)

# construct sample tibble:
df <- tibble(
  key = rep(1:2, c(6,4)),
  Date = c(seq(as.Date('2016-12-17'), as.Date('2016-12-19'), '1 day'),
           seq(as.Date('2016-12-21'), as.Date('2016-12-23'), '1 day'),
           seq(as.Date('2017-05-18'), as.Date('2017-05-21'), '1 day'))          
)

我尝试使用 lag（） 添加标签（ 1 ）以指示日期之间是否有间隔，然后计算的最大长度使用 rle 在列中输入0 ，但这不适用于键中连续日期和间隔的所有可能配置。

I tried to use lag() to add a tag (1) to indicate when there was a gap between dates, and then count the max length of 0 in the column using rle, but this doesn't work for all possible configurations of consecutive dates and gaps within keys.

是否可以按组返回最大连续日期数？

Is there a way to return the maximum number of consecutive dates by group?

推荐答案

让我们首先创建一个函数，该函数将找到最大连续天数s，给定一个向量：

Let's first make a function that would find the maximum number of consecutive days, given a vector:

gl <- function(x) {
  y <- c(unclass(diff(x)))  # c and unclass -- preparing it for rle
  r <- rle(y)
  with(r, max(lengths[values==1]))
}

现在我们可以使用通常的dplyrry方法：

Now we can use it the usual dplyrry way:

df %>% group_by(key) %>% summarise(max.consecutive = gl(Date))

#  A tibble: 2 x 2
#     key max.consecutive
#   <int>           <int>
# 1     1               2
# 2     2               3

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