CODEWITHSUNDEEP
julia
John Zicker
John Zicker

Reputation: 115

julia datetime week number for usa

The week() function in Julia DateTime implementation returns week number of the year using ISO Calendar which means monday is first day of the week. In the USA Sunday is the first day of week which causes Sundays to have week number of decremented by 1. Is there a way to specify the first day of the week as Sunday for week() function?

Upvotes: 2

Views: 422

Answers (1)

Jeremy
Jeremy

Reputation: 631

Monday is baked into the code.

It looks like you just have to deal with it.

d = DateTime(2017,11,25) # Saturday
w = Dates.issunday(d) ? Dates.week(d) + 1 : Dates.week(d)
# 47

d = DateTime(2017,11,26) # Sunday
w = Dates.issunday(d) ? Dates.week(d) + 1 : Dates.week(d)
# 48

Julia 0.6.1 See JuliaDirectory/share/julia/base/dates/accessors.jl line 35

# https://en.wikipedia.org/wiki/Talk:ISO_week_date#Algorithms
const WEEK_INDEX = (15, 23, 3, 11)
function week(days)
    w = div(abs(days - 1), 7) % 20871
    c, w = divrem((w + (w >= 10435)), 5218)
    w = (w * 28 + WEEK_INDEX[c + 1]) % 1461
    return div(w, 28) + 1
end

Upvotes: 4

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