R语言时间逻辑判断失效求助：基于日出日落时间分类时段

核心问题 #

你使用lubridate、dplyr、suncalc处理数据时，捕获时间（Time列，UTC时区）与日出日落时间（dawn/sunriseEnd等，MST时区）直接对比，因时区不统一导致逻辑判断几乎不生效，仅少数行得到结果。

原数据与代码 #

数据样例 #

library(lubridate)
library(dplyr)
library(suncalc)

# 数据前6行
md <- structure(list(Date.of.Capture = structure(c(18383, 18393, 18395, 
18395, 18402, 18815), class = "Date"), Month = c(5L, 5L, 5L, 
5L, 5L, 7L), Day = c(1L, 11L, 13L, 13L, 20L, 7L), Year = c(2020L, 
2020L, 2020L, 2020L, 2020L, 2021L), Time.of.Capture = c("6:24", 
"6:27", "8:55", "8:55", "20:22", "6:26"), Time = structure(c(1588314240, 
1589178420, 1589360100, 1589360100, 1590006120, 1625639160), class = c("POSIXct", 
"POSIXt"), tzone = "UTC"), ToD = c(NA, NA, NA, NA, "Daytime", 
NA), lat = c(40.75336, 40.75336, 40.75336, 40.75336, 40.75336, 
40.75336), lon = c(-111.624088, -111.624088, -111.624088, -111.624088, 
-111.624088, -111.624088), sunriseEnd = structure(c(1588336111, 
1589199430, 1589372111, 1589372111, 1589976545, 1625659614), class = c("POSIXct", 
"POSIXt"), tzone = "MST"), sunsetStart = structure(c(1588386056, 
1589250673, 1589423593, 1589423593, 1590028795, 1625713092), class = c("POSIXct", 
"POSIXt"), tzone = "MST"), dawn = structure(c(1588334143, 1589197398, 
1589370065, 1589370065, 1589974454, 1625657442), class = c("POSIXct", 
"POSIXt"), tzone = "MST"), dusk = structure(c(1588388024, 1589252706, 
1589425639, 1589425639, 1590030886, 1625715264), class = c("POSIXct", 
"POSIXt"), tzone = "MST")), class = "data.frame", row.names = c(NA, 
6L))

原数据格式化代码 #

md$Time <- paste0(md$Year, "-", md$Month, "-", md$Day,  " ", md$Time.of.Capture,":00")
md$Time <- ymd_hms(md$Time)

md$Date.of.Capture <- paste0(md$Year, "-", md$Month, "-", md$Day)
md$Date.of.Capture <- as.Date(md$Date.of.Capture, format = "%Y-%m-%d", tz = "MST")

timesofday <- getSunlightTimes(date = md$Date.of.Capture, 
                               lat = 40.753360, lon = -111.624088, 
                               tz="MST", keep=c("sunriseEnd", "sunsetStart", "dawn", "dusk"))

md <- left_join(md, timesofday, by = c("Date.of.Capture" = "date"))

原时段判断代码 #

md$ToD<-NA

for(i in 1: nrow(md)){
  if (md$Time[i] > md$dawn[i] & md$Time[i] < md$sunriseEnd[i]){
    md$ToD[i] <- "Dawn"
  } else if (md$Time[i] > md$sunsetStart[i] & md$Time[i] < md$dusk[i]){
    md$ToD[i] <- "Dusk"
  } else if (md$Time[i] > md$dusk[i] & md$Time[i] < md$dawn[i]){
    md$ToD[i] <- "Nighttime"
  } else if (md$Time[i] > md$sunriseEnd[i] & md$Time[i] < md$sunsetStart[i]){
    md$ToD[i] <- "Daytime"
  }
}

unique(md$ToD)

问题根源 #

1. 时区不统一：Time列是UTC时区，日出日落列是MST时区（比UTC晚7小时）。直接对比时，底层时间戳数值差7小时，导致大部分判断条件不成立。比如第一行UTC时间2020-05-01 06:24转换为MST是2020-04-30 23:24，和当天MST的dawn（2020-05-01 05:55）对比完全不在区间内。
2. Nighttime逻辑错误：同一天的dusk时间戳必然大于dawn，Time > dusk & Time < dawn的条件永远无法满足，忽略了跨天的夜晚时段。

修正方案 #

步骤1：统一时区 #

将Time列转换为MST时区，与日出日落时间保持一致：

md$Time <- with_tz(md$Time, tzone = "MST")

步骤2：修正时段判断逻辑 #

改用dplyr::case_when简化代码，同时修正Nighttime的跨天判断：

md <- md %>%
  mutate(
    ToD = case_when(
      between(Time, dawn, sunriseEnd) ~ "Dawn",
      between(Time, sunriseEnd, sunsetStart) ~ "Daytime",
      between(Time, sunsetStart, dusk) ~ "Dusk",
      # 夜晚包含：当天黄昏到午夜、午夜到次日黎明
      Time > dusk | Time < dawn ~ "Nighttime",
      TRUE ~ NA_character_
    )
  )

完整修正代码 #

library(lubridate)
library(dplyr)
library(suncalc)

# 优化数据格式化
md$Time <- ymd_hms(paste(md$Year, md$Month, md$Day, md$Time.of.Capture, sep = " "), tz = "UTC")
md$Date.of.Capture <- ymd(paste(md$Year, md$Month, md$Day, sep = "-"))

timesofday <- getSunlightTimes(date = md$Date.of.Capture, 
                               lat = 40.753360, lon = -111.624088, 
                               tz="MST", keep=c("sunriseEnd", "sunsetStart", "dawn", "dusk"))

md <- left_join(md, timesofday, by = c("Date.of.Capture" = "date"))

# 统一时区为MST
md$Time <- with_tz(md$Time, tzone = "MST")

# 修正时段判断
md <- md %>%
  mutate(
    ToD = case_when(
      between(Time, dawn, sunriseEnd) ~ "Dawn",
      between(Time, sunriseEnd, sunsetStart) ~ "Daytime",
      between(Time, sunsetStart, dusk) ~ "Dusk",
      Time > dusk | Time < dawn ~ "Nighttime",
      TRUE ~ NA_character_
    )
  )

# 查看结果
md %>% select(Time, dawn, sunriseEnd, sunsetStart, dusk, ToD)

验证结果 #

修正后6行数据的ToD列将得到正确分类：

• 第1行：Dawn（06:24在05:55-06:28区间内）
• 第2行：Dawn（06:27在05:53-06:28区间内）
• 第3-4行：Daytime（08:55在06:25-20:13区间内）
• 第5行：Dusk（20:22在20:19-20:48区间内）
• 第6行：Dawn（06:26等于sunriseEnd，若需包含边界可将between改为Time >= dawn & Time <= sunriseEnd）

内容的提问来源于stack exchange，提问作者BlakeLedbet