r-检查8天内每个ID的观察次数

Question

在下面的数据集中，我想知道每个ID在8天的块中有多少观测值。解决这一问题的最佳方法是什么？

library(lubridate)
library(tidyverse)
date <- rep_len(seq(dmy("01-01-2013"), dmy("31-12-2013"), by = "days"), 300)
ID <-  rep(c("A","B","C"), 50)
deer <- data.frame(date = date,
utm_x = runif(length(date), min = 238785, max = 453354.5),
utm_y = runif(length(date), min = 4096853.0  , max = 4280487.1 ),
ID)
deer$julian <- yday(as.Date(deer$date))
deer$month <- month(deer$date)
deer$year <- year(deer$date)

我已经能够获得每个ID的观测总数，但我不确定如何查看数据集中每个ID在每8天内有多少观测：

# Observation Distribution 
count <- data.frame(table(df$AnimalID))
colnames(count)[1] <- "ID"

Answer 1

我们可以用ceiling_date创建一个分组变量，然后用n()获得count或summarise

library(dplyr)
library(lubridate)
deer %>% 
group_by(ID) %>%
mutate(eight_day_period = ceiling_date(date, "8 day")) %>%
ungroup %>%
count(ID, eight_day_period)