如果时间在 12 小时和 24 小时时间之间混合，如何转换字符日期时间？

Question

I have a large number of data that I read from various .csv files (using read_csv). The Datetime column is read in the files is read as a class character. I need to convert this character column into the actual date time (and check for duplicates) for plotting purposes. This gets interesting because the date isn't consistently in 12 hour or 24 hour format. The time zone isn't consistent either, but I think I have that bit working correctly.

I am relatively new to R and will take kindly to any positive suggestions.

This is how I am trying to do it presently:

# Add time zone information:
    # Some data uses 12-hour clock:
    if (sum(grep("AM", Data$Date))||sum(grep("PM", Data$Date))>0){
      if (Time_Zone == "Eastern Daylight Time"){
        Data$Date_Formatted <- as.POSIXct(Data$Date, "%m/%d/%Y %H:%M:%S", tz = "America/New_York")
        Data$Date_Formatted2 <- as.POSIXlt(Data$Date, "%m/%d/%Y %H:%M:%S", tz = "America/New_York")
      }
      else if (Time_Zone == "Central Daylight Time" || Time_Zone == "Central Standard Time") {
        Data$Date_Formatted <- as.POSIXct(Data$Date, "%m/%d/%Y %H:%M:%S", tz = "America/Chicago")
        Data$Date_Formatted2 <- as.POSIXlt(Data$Date, "%m/%d/%Y %H:%M:%S", tz = "America/Chicago")
      }
    }
    # Other data uses a 24-hour clock:
    else{
      if (Time_Zone == "Eastern Daylight Time"){
        Data$Date_Formatted <- as.POSIXct(Data$Date, "%m/%d/%Y %k", tz = "America/New_York")
        Data$Date_Formatted2 <- as.POSIXlt(Data$Date, "%m/%d/%Y %k", tz = "America/New_York")
      }
      else if (Time_Zone == "Central Daylight Time" || Time_Zone == "Central Standard Time") {
        Data$Date_Formatted <- as.POSIXct(Data$Date, "%m/%d/%Y %k", tz = "America/Chicago")
        Data$Date_Formatted2 <- as.POSIXlt(Data$Date, "%m/%d/%Y %k", tz = "America/Chicago")
      }
    }

I am not sure what the difference is between POSIXct and POSIXlt and found another thread that used both... so I did... I don't think that is necessary though.

The 12-hour solution seems to be working just fine, but the 24-hour format must still be incorrect.

Answer 1

Try lubridate , it is a very robust package for dates and times:

library(lubridate)

ymd_hms(c("2019-01-20 10:25:00 PM", "2019-01-20 22:25:00"))
[1] "2019-01-20 22:25:00 UTC" "2019-01-20 22:25:00 UTC"

Check ?ymd_hms for more options.