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isentropicknueselinkydragonViralBShahadienes
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add ISO year / ISO week utilities (#48507)
Based on some discussion in https://discourse.julialang.org/t/determine-date-range-given-year-and-week-number/93878 and the relevant issue #48490 I created a couple of utilities to help handle 2023-W05-4 (YYYY-WWW-D) dateformats (https://en.wikipedia.org/wiki/ISO_week_date) Currently there is no functionality of ISO Week with weekday | 2023-W05-4 in Julia, but this could be good start and could help a lot of people who require such dateformat. Notably, with `firstmondayofyear` it is trivial to convert from week format 2023-W05-4 to usual date format 2023-02-02 as: ``` firstmondayofyear(Date(2023)) + Week(5 - 1) + Day(3) ``` This was otherwise impossible within std lib --------- Co-authored-by: Jeremie Knuesel <[email protected]> Co-authored-by: woclass <[email protected]> Co-authored-by: Viral B. Shah <[email protected]> Co-authored-by: Andy Dienes <[email protected]>
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‎stdlib/Dates/src/Dates.jl‎

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@@ -60,6 +60,7 @@ export Period, DatePeriod, TimePeriod,
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yearmonthday, yearmonth, monthday, year, month, week, day,
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hour, minute, second, millisecond, dayofmonth,
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microsecond, nanosecond,
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isoweekdate, isoyear, weeksinyear,
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# query.jl
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dayofweek, isleapyear, daysinmonth, daysinyear, dayofyear, dayname, dayabbr,
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dayofweekofmonth, daysofweekinmonth, monthname, monthabbr,

‎stdlib/Dates/src/accessors.jl‎

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@@ -32,6 +32,8 @@ function day(days)
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y = fld(100b + h, 36525); c = b + z - 365y - fld(y, 4); m = div(5c + 456, 153)
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return c - div(153m - 457, 5)
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end
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# ISO year utils
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# https://en.wikipedia.org/wiki/Talk:ISO_week_date#Algorithms
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const WEEK_INDEX = (15, 23, 3, 11)
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function week(days)
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return div(w, 28) + 1
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end
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"""
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Return the number of ISO weeks in the given year (see https://en.wikipedia.org/wiki/ISO_week_date).
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# Examples
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```jldoctest
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julia> weeksinyear(Year(2022))
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52
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julia> weeksinyear(Year(2020))
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53
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```
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!!! compat "Julia 1.13"
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This function requires Julia 1.13 or later.
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"""
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function weeksinyear(y::Year)
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firstday = firstdayofyear(Date(y))
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lastday = lastdayofyear(Date(y))
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if dayofweek(firstday) == 4 || dayofweek(lastday) == 4
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return 53
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end
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return 52
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end
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"""
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Return the ISO year that contains `dt` (see https://en.wikipedia.org/wiki/ISO_week_date).
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# Examples
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```jldoctest
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julia> isoyear(Date(2022, 1, 1))
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2021 years
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julia> isoyear(Date(2021, 12, 31))
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2021 years
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```
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!!! compat "Julia 1.13"
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This function requires Julia 1.13 or later.
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"""
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function isoyear(dt::DateTime)
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thisyear = Year(dt)
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thismonth = Month(dt)
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weeknumber = week(dt)
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if weeknumber >= 52 && thismonth.value == 1
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# If it is january, then its the iso year from before
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return Year(thisyear.value - 1)
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elseif weeknumber == 1 && thismonth.value == 12
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# If it is december, then its the next year
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return Year(thisyear.value + 1)
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else
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return thisyear
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end
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end
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isoyear(dt::Date) = isoyear(DateTime(dt))
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"""
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Return the ISO week date that corresponds to `dt` (see
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https://en.wikipedia.org/wiki/ISO_week_date).
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The return type is a tuple of `Year`, `Week` and `Int64` (from 1 to 7).
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# Examples
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```jldoctest
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julia> isoweekdate(Date(2023, 03, 06))
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(2023, 10, 1)
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julia> isoweekdate(Date(2023, 01, 01))
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(2022, 52, 7)
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```
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!!! compat "Julia 1.13"
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This function requires Julia 1.13 or later.
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"""
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isoweekdate(dt::DateTime) = (isoyear(dt).value, week(dt), dayofweek(dt))
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isoweekdate(dt::Date) = isoweekdate(DateTime(dt))
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function quarter(days)
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m = month(days)
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return m < 4 ? 1 : m < 7 ? 2 : m < 10 ? 3 : 4

‎stdlib/Dates/test/accessors.jl‎

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dt1 = dt1 + Dates.Day(1)
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end
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end
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@testset "ISO year utils" begin
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# Tests from https://www.epochconverter.com/weeks
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@test Dates.weeksinyear(Dates.Year(2023)) == 52
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@test Dates.weeksinyear(Dates.Year(2022)) == 52
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@test Dates.weeksinyear(Dates.Year(2021)) == 52
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@test Dates.weeksinyear(Dates.Year(2020)) == 53
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@test Dates.weeksinyear(Dates.Year(2019)) == 52
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@test Dates.weeksinyear(Dates.Year(2018)) == 52
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@test Dates.weeksinyear(Dates.Year(2017)) == 52
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@test Dates.weeksinyear(Dates.Year(2016)) == 52
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@test Dates.weeksinyear(Dates.Year(2015)) == 53
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@test Dates.weeksinyear(Dates.Year(2014)) == 52
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@test Dates.weeksinyear(Dates.Year(2013)) == 52
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@test Dates.weeksinyear(Dates.Year(2012)) == 52
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@test Dates.weeksinyear(Dates.Year(2011)) == 52
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@test Dates.weeksinyear(Dates.Year(2010)) == 52
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@test Dates.weeksinyear(Dates.Year(2009)) == 53
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# From python datetime isocalendar
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@test Dates.isoweekdate(Dates.Date(2023, 03, 06)) == (2023, 10, 1)
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@test Dates.isoweekdate(Dates.Date(2023, 03, 07)) == (2023, 10, 2)
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@test Dates.isoweekdate(Dates.Date(2023, 03, 08)) == (2023, 10, 3)
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@test Dates.isoweekdate(Dates.Date(2022, 12, 29)) == (2022, 52, 4)
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@test Dates.isoweekdate(Dates.Date(2022, 12, 30)) == (2022, 52, 5)
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@test Dates.isoweekdate(Dates.Date(2022, 12, 31)) == (2022, 52, 6)
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@test Dates.isoweekdate(Dates.Date(2023, 01, 01)) == (2022, 52, 7)
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@test Dates.isoweekdate(Dates.Date(2023, 01, 02)) == (2023, 1, 1)
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@test Dates.isoweekdate(Dates.Date(2023, 01, 03)) == (2023, 1, 2)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 28)) == (2021, 52, 2)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 29)) == (2021, 52, 3)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 30)) == (2021, 52, 4)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 31)) == (2021, 52, 5)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 01)) == (2021, 52, 6)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 02)) == (2021, 52, 7)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 03)) == (2022, 1, 1)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 04)) == (2022, 1, 2)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 05)) == (2022, 1, 3)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 06)) == (2022, 1, 4)
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@test Dates.isoweekdate(Dates.Date(2020, 12, 29)) == (2020, 53, 2)
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@test Dates.isoweekdate(Dates.Date(2020, 12, 30)) == (2020, 53, 3)
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@test Dates.isoweekdate(Dates.Date(2020, 12, 31)) == (2020, 53, 4)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 01)) == (2020, 53, 5)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 02)) == (2020, 53, 6)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 03)) == (2020, 53, 7)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 04)) == (2021, 1, 1)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 05)) == (2021, 1, 2)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 31)) == (2021, 52, 5)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 01)) == (2021, 52, 6)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 02)) == (2021, 52, 7)
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@test Dates.isoweekdate(Dates.Date(2020, 12, 31)) == (2020, 53, 4)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 01)) == (2020, 53, 5)
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@test Dates.isoweekdate(Dates.Date(2021, 01, 02)) == (2020, 53, 6)
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@test Dates.isoweekdate(Dates.Date(2021, 12, 31)) == (2021, 52, 5)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 01)) == (2021, 52, 6)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 02)) == (2021, 52, 7)
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@test Dates.isoweekdate(Dates.Date(2022, 01, 03)) == (2022, 1, 1)
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@test Dates.isoweekdate(Dates.Date(2019, 12, 31)) == (2020, 1, 2)
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@test Dates.isoweekdate(Dates.Date(2020, 01, 01)) == (2020, 1, 3)
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@test Dates.isoweekdate(Dates.Date(2020, 01, 02)) == (2020, 1, 4)
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@test Dates.isoweekdate(Dates.Date(2018, 12, 31)) == (2019, 1, 1)
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@test Dates.isoweekdate(Dates.Date(2019, 01, 01)) == (2019, 1, 2)
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@test Dates.isoweekdate(Dates.Date(2019, 01, 02)) == (2019, 1, 3)
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end
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@testset "Vectorized accessors" begin
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a = Dates.Date(2014, 1, 1)
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dr = [a, a, a, a, a, a, a, a, a, a]

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