Date and Time defaulting to Jan 01, 1AD in Lubridate R package - r

Question

folks...
I am having trouble with date/time showing up properly in lubridate.
Here's my code:
Temp.dat <- read_excel("Temperature Data.xlsx", sheet = "Sheet1", na="NA") %>%
mutate(Treatment = as.factor(Treatment),
TempC=as.factor(TempC),
TempF=as.factor(TempF),
Month=as.factor(Month),
Day=as.factor(Day),
Year=as.factor(Year),
Time=as.factor(Time))%>%
select(TempC, Treatment, Month, Day, Year, Time)%>%
mutate(Measurement=make_datetime(Month, Day, Year, Time))
Here's what it spits out:
tibble [44 x 7] (S3: tbl_df/tbl/data.frame)
$ TempC : Factor w/ 38 levels "15.5555555555556",..: 31 32 29 20 17 28 27 26 23 24 ...
$ Treatment : Factor w/ 2 levels "Grass","Soil": 1 1 1 1 2 2 2 2 2 2 ...
$ Month : Factor w/ 1 level "6": 1 1 1 1 1 1 1 1 1 1 ...
$ Day : Factor w/ 2 levels "15","16": 1 1 1 1 1 1 1 1 1 1 ...
$ Year : Factor w/ 1 level "2022": 1 1 1 1 1 1 1 1 1 1 ...
$ Time : Factor w/ 3 levels "700","1200","1600": 3 3 3 3 3 3 3 3 3 3 ...
**$ Measurement: POSIXct[1:44], format: "0001-01-01 03:00:00" "0001-01-01 03:00:00" "0001-01-01 03:00:00" "0001-01-01 03:00:00" ...**
I've put asterisks by the problem result. It should spit out June 16th at 0700 or something like that, but instead it's defaulting to January 01, 1AD for some reason. I've tried adding colons to the date in excel, but that defaults to a 12-hour timecycle and I'd like to keep this at 24 hours.
What's going on here?

Answer 1

This will work as long as the format in the excel file for date is set to time, and it imports as a date-time object that lubridate can interpret.
library(dplyr)
library(lubridate)
Temp.dat <- read_excel("t.xlsx", sheet = "Sheet1", na="NA") %>%
mutate(Treatment = as.factor(Treatment),
TempC = as.numeric(TempC),
TempF = as.numeric(TempF),
Month = as.numeric(Month),
Day = as.numeric(Day),
Year = as.numeric(Year),
Hour = hour(Time),
Minute = minute(Time)) %>%
select(TempC, Treatment, Month, Day, Year, Hour, Minute) %>%
mutate(Measurement = make_datetime(year = Year,
month = Month,
day = Day,
hour = Hour,
min = Minute))
Notice the value for the arguments for make_datetime() are set to numeric, which is what the function expects. If you pass factors, the function gives you the weird dates you were seeing.
No need to convert Time to string and extract hours and minutes, as I suggested in the comments, since you can use lubridate's minute() and hour() functions.
EDIT
In order to be able to use lubridate's functions Time needs to be a date-time object. You can check that it is by looking at what read_excel() produces
> str(read_excel("t.xlsx", sheet = "Sheet1", na="NA"))
tibble [2 × 7] (S3: tbl_df/tbl/data.frame)
$ Treatment: chr [1:2] "s" "c"
$ TempC : num [1:2] 34 23
$ TempF : num [1:2] 99 60
$ Month : num [1:2] 5 4
$ Day : num [1:2] 1 15
$ Year : num [1:2] 2020 2021
$ Time : POSIXct[1:2], format: "1899-12-31 04:33:23" "1899-12-31 03:20:23"
See that Time is type POSIXct, a date-time object. If it is not, then you need to convert it into one if you want to use lubridate's minute() and hour() functions. If it cannot be converted, there are other solutions, but they depend on what you have.