# Better DOY Conversion?

**URL:** <https://discourse.julialang.org/t/better-doy-conversion/3744>\
**Category:** General Usage\
**Tags:** dates\
**Created:** [May 16, 2017, 12:26pm UTC](https://discourse.julialang.org/t/better-doy-conversion/3744 "2017-05-16T12:26:44Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Daneel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/daneel/32/175_2.png) [@Daneel](https://discourse.julialang.org/u/Daneel)\
**Post date:** [May 16, 2017, 12:26pm UTC](https://discourse.julialang.org/t/better-doy-conversion/3744/1 "2017-05-16T12:26:44Z")

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Is there an easy way of converting a DateTime to a string with Day Of Year (DOY)?

```julia
julia> time = DateTime(2017,5,16,14,20)
julia> floor(convert(Float64,time - DateTime(Dates.Year(time)) + DateTime(Dates.Day(1)))/1000/60/60/24)
136.0

```

Ideally I _could_ just do something like this.

```julia
julia> dfmt = Dates.DateFormat("yyyyddd_HHMMSS")
julia> Dates.format(time,dfmt)
"2017136_142000"

```

Dates doesn’t appear to have a DOY formatting string though.

[https://github.com/JuliaLang/julia/blob/master/test/dates/io.jl](https://github.com/JuliaLang/julia/blob/master/test/dates/io.jl)

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<div class="post-metadata">

**Author:** ![helgee](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/helgee/32/2022_2.png) [@helgee](https://discourse.julialang.org/u/helgee)\
**Post date:** [May 16, 2017, 12:55pm UTC](https://discourse.julialang.org/t/better-doy-conversion/3744/2 "2017-05-16T12:55:57Z")

</div>

```julia
julia> time = DateTime(2017,5,16,14,20)
julia> Dates.dayofyear(time)

```

It would be good if there was a format string option, though.

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<div class="post-metadata">

**Author:** ![Daneel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/daneel/32/175_2.png) [@Daneel](https://discourse.julialang.org/u/Daneel)\
**Post date:** [May 16, 2017, 2:02pm UTC](https://discourse.julialang.org/t/better-doy-conversion/3744/3 "2017-05-16T14:02:42Z")

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No idea how I missed that one but thank you for pointing that out. If I ever figure out Github I’ll see if I can add a DOY option to the formats.

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<div class="post-metadata">

**Author:** ![helgee](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/helgee/32/2022_2.png) [@helgee](https://discourse.julialang.org/u/helgee)\
**Post date:** [May 16, 2017, 2:04pm UTC](https://discourse.julialang.org/t/better-doy-conversion/3744/4 "2017-05-16T14:04:20Z")

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You could start by opening an issue 👍