Converting dates to excel compatible

General Usage
1

I use dates in julia, then I convert them in days in the following fashion

# Convert a date to a number of days
date = Date(2023, 6, 7)
days = Dates.days(date)
println(days)
738678

I then look up the dates with other values to create an array that I want to export in excel. My issue is that dates are then in the julia format above (i.e. in actual number of dates)

Is there a way to convert days back into a date that I can use in excel?

2

There are apparently two formats, do you know which Excel format?

3

So the Dates.days function seems to reference to year 1, January 1. Microsoft seems to use the 1904 system? The difference in days is then:

julia> Dates.days(Date("0001-01-01"))
1

julia> Dates.days(Date("1904-01-01"))
695056
4

Newer versions of excel use 1900 as a base year. I can do the difference in dates then and see. I was wondering if there’s a more immediate way to work with dates in julia. Coming from matlab I never did bother that much working with arrays of time which I could easily use in excel.

5

What do you mean by “more immediate way”? Why not just write the Dates to Excel?

julia> using XLSX, Dates

julia> XLSX.writetable("out.xlsx", (x = Date(2010):Year(1):Date(2019), y = rand(10)))

gives:

image

Or is your question about how to get the date back from 738678 in Julia?

julia> Dates.epochdays2date(738678) + Year(1)
2023-06-07