R 时间格式转换

Question

I have almost finished my script but I have a problem with my dates format. I installed lubridate package used the as_date function, but it doesn't give me what I want (a date). "time" is my variable, I put its description below.

I do not put my entire script since the concern is only about this format question (and it implies a huge.netcdf file impossible to download)

Could you help me please?

class(time)
[1] "array"

head(time)
[1] 3573763200 3573774000 3573784800 3573795600 3573806400 3573817200

tunits
$long_name
[1] "time in seconds (UT)"
$standard_name
[1] "time"
$units
[1] "seconds since 1900-01-01T00:00:00Z"
$axis
[1] "T"
$time_origin
[1] "01-JAN-1900 00:00:00"
$conventions
[1] "relative number of seconds with no decimal part"

#conversion
date = as_date(time,tz="UTC",origin = "1900-01-01")
head(date)
[1] "-5877641-06-23" "-5877641-06-23" "-5877641-06-23" "-5877641-06-23"
[5] "-5877641-06-23" "-5877641-06-23"

Answer 1

as_date() calculates the date using the number of days since the origin.

What you are looking for seems to be as_datetime() also from the lubridate package which calculates the date using the number of seconds since the origin. In your example this would be:

time <- c(3573763200,3573774000,3573784800,3573795600,3573806400,3573817200)
date <- as_datetime(time, tz = "UTC", origin = "1900-01-01") %>% date()

Using a dplyr pipe and the date() function from lubridate to extract the date from the as_datetime() function.

Answer 2

Time is in seconds since 01/01/1900. Converting a value in time to an actual date would work as follows, using the seconds methods in lubridate :

lubridate::ymd("1900-01-01") + lubridate::seconds(3573763200)

You can vectorize it:

lubridate::ymd("1900-01-01") + lubridate::seconds(time)

Answer 3

date <- as_date(time/(24*60*60), tz = "UTC", origin = "1900-01-01") date