R StackApply：从每日数据创建一个 8 天的索引，同时计算年份

Question

我想创建一个索引，我可以在 StackApply 中使用它来将每日降雨量栅格堆栈聚合成 8 天的总和，同时计算年份。让我用一些代码来说明。这是正常的顺序每日数据的样子：

> seq.Date(as.Date("2001-11-01"), as.Date("2002-01-31"),by=1)
 [1] "2001-11-01" "2001-11-02" "2001-11-03" "2001-11-04" "2001-11-05" "2001-11-06" "2001-11-07"
 [8] "2001-11-08" "2001-11-09" "2001-11-10" "2001-11-11" "2001-11-12" "2001-11-13" "2001-11-14"
[15] "2001-11-15" "2001-11-16" "2001-11-17" "2001-11-18" "2001-11-19" "2001-11-20" "2001-11-21"
[22] "2001-11-22" "2001-11-23" "2001-11-24" "2001-11-25" "2001-11-26" "2001-11-27" "2001-11-28"
[29] "2001-11-29" "2001-11-30" "2001-12-01" "2001-12-02" "2001-12-03" "2001-12-04" "2001-12-05"
[36] "2001-12-06" "2001-12-07" "2001-12-08" "2001-12-09" "2001-12-10" "2001-12-11" "2001-12-12"
[43] "2001-12-13" "2001-12-14" "2001-12-15" "2001-12-16" "2001-12-17" "2001-12-18" "2001-12-19"
[50] "2001-12-20" "2001-12-21" "2001-12-22" "2001-12-23" "2001-12-24" "2001-12-25" "2001-12-26"
[57] "2001-12-27" "2001-12-28" "2001-12-29" "2001-12-30" "2001-12-31" "2002-01-01" "2002-01-02"
[64] "2002-01-03" "2002-01-04" "2002-01-05" "2002-01-06" "2002-01-07" "2002-01-08" "2002-01-09"
[71] "2002-01-10" "2002-01-11" "2002-01-12" "2002-01-13" "2002-01-14" "2002-01-15" "2002-01-16"
[78] "2002-01-17" "2002-01-18" "2002-01-19" "2002-01-20" "2002-01-21" "2002-01-22" "2002-01-23"
[85] "2002-01-24" "2002-01-25" "2002-01-26" "2002-01-27" "2002-01-28" "2002-01-29" "2002-01-30"
[92] "2002-01-31"

如果我将这些每日值按 8 天的时间间隔排序，结果如下：

> seq.Date(as.Date("2001-11-01"), as.Date("2002-01-31"),by=8)
 [1] "2001-11-01" "2001-11-09" "2001-11-17" "2001-11-25" "2001-12-03" "2001-12-11" "2001-12-19"
 [8] "2001-12-27" "2002-01-04" "2002-01-12" "2002-01-20" "2002-01-28"

它会延续到下一年，就像从一个月延续到下一年一样（每月都可以延续）。这只是问题的一部分，因为我希望最终产品是我可以在 StackApply 中使用的索引。因此，以上面的 8 天为例，指数应如下所示：

> rep(1:12,times=c(8,8,8,8,8,8,8,5,8,8,8,7))
 [1]  1  1  1  1  1  1  1  1  2  2  2  2  2  2  2  2  3  3  3  3  3  3  3  3  4  4  4  4  4  4  4
[32]  4  5  5  5  5  5  5  5  5  6  6  6  6  6  6  6  6  7  7  7  7  7  7  7  7  8  8  8  8  8  9
[63]  9  9  9  9  9  9  9 10 10 10 10 10 10 10 10 11 11 11 11 11 11 11 11 12 12 12 12 12 12 12

请注意命令中间的 5，这表示它在 2001 年 12 月 31 日停止并且不会循环到 2002 年。总而言之，我想创建一个索引，每个 8-全年的天间隔，但不会延续到下一年。我有超过 20 年的每日数据的栅格堆栈，因此这将是一个非常长的索引。

在此先感谢您的帮助！

Answer 1

也许有点变通办法，但这应该可行：

library(dplyr)
library(lubridate)
df <- data.frame(date = seq.Date(as.Date("2000-01-01"), as.Date("2010-12-31"), "day"))

df %>% 
  mutate(year = year(date)) %>% 
  group_by(year) %>% 
  mutate(index = rep(seq_along(df$date), each = 8)[1:max(yday(date))]) %>% 
  ungroup() %>% 
  mutate(index = index + 46 * (year - min(year)))

R StackApply：从每日数据创建一个 8 天的索引，同时计算年份

R StackApply: create an 8-day index from daily data while accounting for year

indexing

r

raster

r-raster