# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1799

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 1800

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## [Equal size of subplots](https://discourse.julialang.org/t/equal-size-of-subplots/36084)

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**Author:** [@saurabh](https://discourse.julialang.org/u/saurabh)\
**Replies:** 1\
**Last updated:** [March 17, 2020, 10:58am UTC](https://discourse.julialang.org/t/equal-size-of-subplots/36084 "2020-03-17T10:58:36Z")

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OS: WIndows 10 Julia Version: 1.3.1 I tried to plot the original image and its 2D Fourier spectrum. Currently, the size of subplots is different. I have tried to change aspect ratio of each plot and also of subplot as …

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## [Great paper on performance and hardware](https://discourse.julialang.org/t/great-paper-on-performance-and-hardware/36093)

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**Author:** [@jakobnissen](https://discourse.julialang.org/u/jakobnissen)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 10:50am UTC](https://discourse.julialang.org/t/great-paper-on-performance-and-hardware/36093 "2020-03-17T10:50:41Z")

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About 6 months back, a user on Slack posted a great paper on coding optimization. It was very long and went into detail on all relevant aspects of how RAM and CPUs work. Can anyone remember the name of it? Already answe…

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## [What is the DataFramesMeta way to specify a column by its name in a variable?](https://discourse.julialang.org/t/what-is-the-dataframesmeta-way-to-specify-a-column-by-its-name-in-a-variable/35954)

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**Author:** [@shg](https://discourse.julialang.org/u/shg)\
**Replies:** 6\
**Last updated:** [March 17, 2020, 10:20am UTC](https://discourse.julialang.org/t/what-is-the-dataframesmeta-way-to-specify-a-column-by-its-name-in-a-variable/35954 "2020-03-17T10:20:58Z")

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What is the proper way to specify a column by a string variable containing the column name in a DataFramesMeta query? I tried Symbol(var) but got an error. julia\> df = DataFrame(num = 1:3) 3×1 DataFrame │ Row │ num │ …

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## [Julia-client fail to install](https://discourse.julialang.org/t/julia-client-fail-to-install/36090)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 3\
**Last updated:** [March 17, 2020, 9:56am UTC](https://discourse.julialang.org/t/julia-client-fail-to-install/36090 "2020-03-17T09:56:22Z")

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It’s been like this for a long time :厌倦:

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## [Efficient way of comparing two matrices](https://discourse.julialang.org/t/efficient-way-of-comparing-two-matrices/36044)

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**Author:** [@jmcastro2109](https://discourse.julialang.org/u/jmcastro2109)\
**Replies:** 4\
**Last updated:** [March 17, 2020, 9:35am UTC](https://discourse.julialang.org/t/efficient-way-of-comparing-two-matrices/36044 "2020-03-17T09:35:45Z")

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Hello, this question might seem very naive. But what is the best way of doing a logical comparison of two matrices. Consider the following MWE: function compare(N) for n=1:N X=rand(\[0,1\],4,4) Y=rand(…

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## [I want to create my own module and just use it like other modules](https://discourse.julialang.org/t/i-want-to-create-my-own-module-and-just-use-it-like-other-modules/36043)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 4\
**Last updated:** [March 17, 2020, 8:59am UTC](https://discourse.julialang.org/t/i-want-to-create-my-own-module-and-just-use-it-like-other-modules/36043 "2020-03-17T08:59:37Z")

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julia\> using MyExample ERROR: ArgumentError: Package MyExample not found in current path: - Run \`import Pkg; Pkg.add("MyExample")\` to install the MyExample package. Stacktrace: \[1\] require(::Module, ::Symbol) a…

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## [Segfault on struct creation; gc involved](https://discourse.julialang.org/t/segfault-on-struct-creation-gc-involved/35975)

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**Author:** [@Bodya00](https://discourse.julialang.org/u/Bodya00)\
**Replies:** 6\
**Last updated:** [March 17, 2020, 8:52am UTC](https://discourse.julialang.org/t/segfault-on-struct-creation-gc-involved/35975 "2020-03-17T08:52:39Z")

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Hello and thank you for your time. I have a problem with random segfaults on struct initialization(example attached below). Every stacktrace leads to gc code and every stacktrace goes through struct object initializatio…

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## [A question about Atom/Julia](https://discourse.julialang.org/t/a-question-about-atom-julia/36080)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 3\
**Last updated:** [March 17, 2020, 8:41am UTC](https://discourse.julialang.org/t/a-question-about-atom-julia/36080 "2020-03-17T08:41:01Z")

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Originally, my julia works .Because of my careless ,I have changed my system path then ,when I run a simple code, it slways shows running but it has no consequence .And there is a warning in the repl. I tried so man…

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## [Mapreduce slower than sum](https://discourse.julialang.org/t/mapreduce-slower-than-sum/36046)

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**Author:** [@CFBaptista](https://discourse.julialang.org/u/CFBaptista)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 8:25am UTC](https://discourse.julialang.org/t/mapreduce-slower-than-sum/36046 "2020-03-17T08:25:05Z")

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I am comparing three approaches for a point-wise multiplication of a vector field and a scalar field, followed by a summation over all elements of the resulting vector field. I would like to know why the mapreduce approa…

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## [Automatically make all fields of an (immutable) struct concrete type](https://discourse.julialang.org/t/automatically-make-all-fields-of-an-immutable-struct-concrete-type/36081)

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**Author:** [@lassepe](https://discourse.julialang.org/u/lassepe)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 8:19am UTC](https://discourse.julialang.org/t/automatically-make-all-fields-of-an-immutable-struct-concrete-type/36081 "2020-03-17T08:19:35Z")

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I often find myself introducing a bunch of type parameters to make working with the declared struct faster. For example, I would write struct Foo{TA, TB} a::TA b::TB end and the only purpose of TA and TB is to make s…

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## [Discourse feature request: Autolink names of registered packages](https://discourse.julialang.org/t/discourse-feature-request-autolink-names-of-registered-packages/35731)

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**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 8:15am UTC](https://discourse.julialang.org/t/discourse-feature-request-autolink-names-of-registered-packages/35731 "2020-03-17T08:15:02Z")

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On github you can write #1234 and it will automatically turn into a link to the respective issue/PR. Wouldn’t it be great to have a similar feature here for registered packages? So if you write, say, BenchmarkTools.jl …

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## [Problem in running Julia on Juno](https://discourse.julialang.org/t/problem-in-running-julia-on-juno/35412)

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**Author:** [@Darione](https://discourse.julialang.org/u/Darione)\
**Replies:** 3\
**Last updated:** [March 17, 2020, 6:58am UTC](https://discourse.julialang.org/t/problem-in-running-julia-on-juno/35412 "2020-03-17T06:58:21Z")

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I have disinstalled Julia and Atom many times, and delete the c:\\users\\dario \\ .julia and c:\\users\\dario \\ .atom the same number of times … but it seems juno is blocked … when starting julia REPL in juno, after "Press …

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## [Call a macro within a macro](https://discourse.julialang.org/t/call-a-macro-within-a-macro/3708)

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**Author:** [@matthieu](https://discourse.julialang.org/u/matthieu)\
**Replies:** 8\
**Last updated:** [March 17, 2020, 5:06am UTC](https://discourse.julialang.org/t/call-a-macro-within-a-macro/3708 "2020-03-17T05:06:46Z")

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I am trying to define a macro that calls another macro. To take an example, suppose a package defines a macro @formula as follows: type Formula lhs::Union{Symbol, Expr, Void} rhs::Union{Symbol, Expr, Integer} e…

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## [\`empty!\` for JuMP.Model or JuMP.direct\_model?](https://discourse.julialang.org/t/empty-for-jump-model-or-jump-direct-model/35673)

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**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 12\
**Last updated:** [March 17, 2020, 3:03am UTC](https://discourse.julialang.org/t/empty-for-jump-model-or-jump-direct-model/35673 "2020-03-17T03:03:19Z")

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I did not found a way of emptying a model (created with either JuMP.model or JuMP.direct\_model). There is a MathOptInterface.empty!, but it seems I need to call it over backend(model) and after I do that, I cannot add a…

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## [\[ANN\] MeshCore](https://discourse.julialang.org/t/ann-meshcore/36075)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 0\
**Last updated:** [March 17, 2020, 2:36am UTC](https://discourse.julialang.org/t/ann-meshcore/36075 "2020-03-17T02:36:39Z")

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I have designed a lightweight mesh library for finite element and boundary element methods (GitHub - PetrKryslUCSD/MeshCore.jl: Curation and manipulation of general unstructured meshes for the Finite Element Methods (FEM…

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## [Is there a version of @sync that throws error when the task failed?](https://discourse.julialang.org/t/is-there-a-version-of-sync-that-throws-error-when-the-task-failed/36062)

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**Author:** [@Chong\_Wang](https://discourse.julialang.org/u/Chong_Wang)\
**Replies:** 1\
**Last updated:** [March 17, 2020, 2:10am UTC](https://discourse.julialang.org/t/is-there-a-version-of-sync-that-throws-error-when-the-task-failed/36062 "2020-03-17T02:10:18Z")

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By default, @sync will collect all the exceptions in its block and throw them after everything is done. However, I have a code looking like @sync begin @async for i in 1:1000 # task A end @async f…

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## [How would I save a dictionary of dataframes that I can import to another file?](https://discourse.julialang.org/t/how-would-i-save-a-dictionary-of-dataframes-that-i-can-import-to-another-file/36042)

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**Author:** [@Julia1](https://discourse.julialang.org/u/Julia1)\
**Replies:** 4\
**Last updated:** [March 17, 2020, 2:05am UTC](https://discourse.julialang.org/t/how-would-i-save-a-dictionary-of-dataframes-that-i-can-import-to-another-file/36042 "2020-03-17T02:05:06Z")

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Hi how are you, I have a dictionary where all the values are dataframes. I want to be able to save/export this dictionary of dataframes and import it in another file. Whats the best way to do this?

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## [ANN: LazyStack, SliceMap, StarSlice](https://discourse.julialang.org/t/ann-lazystack-slicemap-starslice/36072)

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**Author:** [@mcabbott](https://discourse.julialang.org/u/mcabbott)\
**Replies:** 1\
**Last updated:** [March 17, 2020, 12:14am UTC](https://discourse.julialang.org/t/ann-lazystack-slicemap-starslice/36072 "2020-03-17T00:14:49Z")

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I have a few small packages for dealing with arrays of arrays, and similar things, which perhaps deserve announcement here: LazyStack.jl has one function stack which glues an array of arrays into one big one. It is al…

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## [Error when using PyPlot and Gtk package](https://discourse.julialang.org/t/error-when-using-pyplot-and-gtk-package/34559)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 5\
**Last updated:** [March 17, 2020, 12:14am UTC](https://discourse.julialang.org/t/error-when-using-pyplot-and-gtk-package/34559 "2020-03-17T00:14:15Z")

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Hi, I am getting errors when using PyPlot and Gtk together: julia\> using PyPlot, Gtk ERROR: InitError: could not load library "/Users/hyzhou/.julia/artifacts/c6f53b0adfb48f611ad41b73461d9419117d3503/lib/libfontconfig.1…

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## [VegaLite add line manually?](https://discourse.julialang.org/t/vegalite-add-line-manually/36033)

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**Author:** [@jling](https://discourse.julialang.org/u/jling)\
**Replies:** 9\
**Last updated:** [March 16, 2020, 10:40pm UTC](https://discourse.julialang.org/t/vegalite-add-line-manually/36033 "2020-03-16T22:40:11Z")

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dfc\_single |\> @filter(\_.gender ∈ \["Male", "Female"\]) |\> @vlplot( :bar, width = 700, y={ "count()", axis={title="Gender fraction"}, stack=:normalize }, x="state", color = …

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## [Arrays of CTypes Memory Layout](https://discourse.julialang.org/t/arrays-of-ctypes-memory-layout/35945)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 15\
**Last updated:** [March 16, 2020, 10:19pm UTC](https://discourse.julialang.org/t/arrays-of-ctypes-memory-layout/35945 "2020-03-16T22:19:26Z")

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I’ve been using Julia 1.3.1 in a kind of hacky way to integrate it into C#. I have no troubles passing C# arrays of say, float’s to Julia and changing them in place. Which is fantastic, but when I try to return an array …

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## [What is the current best practice for building a relocatable shared library?](https://discourse.julialang.org/t/what-is-the-current-best-practice-for-building-a-relocatable-shared-library/36063)

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**Author:** [@rleegates](https://discourse.julialang.org/u/rleegates)\
**Replies:** 0\
**Last updated:** [March 16, 2020, 9:38pm UTC](https://discourse.julialang.org/t/what-is-the-current-best-practice-for-building-a-relocatable-shared-library/36063 "2020-03-16T21:38:56Z")

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The Q&A concerning building shared libraries appear to be quite old and there has been lots of development work in the related PackageCompiler.jl recently. So what is the current best practice for building a relocatable …

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## [Notate the original value form (not logged) in loglog plot](https://discourse.julialang.org/t/notate-the-original-value-form-not-logged-in-loglog-plot/36049)

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**Author:** [@1634](https://discourse.julialang.org/u/1634)\
**Replies:** 7\
**Last updated:** [March 16, 2020, 9:37pm UTC](https://discourse.julialang.org/t/notate-the-original-value-form-not-logged-in-loglog-plot/36049 "2020-03-16T21:37:31Z")

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The x value vector x=\[5e-10, 5e-9, 5e-8, 5e-7, 5e-6\]. If plot(,xticks=x) then it’s marked after logged. Can I notate it by 5e\*\* scale correspondingly? Also, is it possible to tick y=collect(0:10:100) by its original form…

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## [DifferentialEquations.jl ERROR: UndefVarError: CostVData not defined](https://discourse.julialang.org/t/differentialequations-jl-error-undefvarerror-costvdata-not-defined/35939)

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**Author:** [@PharmCat](https://discourse.julialang.org/u/PharmCat)\
**Replies:** 5\
**Last updated:** [March 16, 2020, 9:18pm UTC](https://discourse.julialang.org/t/differentialequations-jl-error-undefvarerror-costvdata-not-defined/35939 "2020-03-16T21:18:38Z")

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I try to otimize function with DifferentialEquations.jl + Optim.jl like in documetation, but I have: ERROR: UndefVarError: CostVData not defined using DifferentialEquations, Plots, Optim, LossFunctions, Random, DiffE…

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## [Reworking SML threading and GC for real time systems (paper)](https://discourse.julialang.org/t/reworking-sml-threading-and-gc-for-real-time-systems-paper/36061)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 0\
**Last updated:** [March 16, 2020, 9:08pm UTC](https://discourse.julialang.org/t/reworking-sml-threading-and-gc-for-real-time-systems-paper/36061 "2020-03-16T21:08:33Z")

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RTMLton: An SML Runtime for Real-Time Systems in Practical Aspects of Declarative Languages (2020 proceedings). from the Abstract and Conclusion: … There has been relatively little progress on adapting more general p…

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## [Copy Julia REPL to a txt file](https://discourse.julialang.org/t/copy-julia-repl-to-a-txt-file/36055)

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**Author:** [@jmcastro2109](https://discourse.julialang.org/u/jmcastro2109)\
**Replies:** 3\
**Last updated:** [March 16, 2020, 9:00pm UTC](https://discourse.julialang.org/t/copy-julia-repl-to-a-txt-file/36055 "2020-03-16T21:00:43Z")

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Hi, How can I copy the printed outputs on my REPL on txt file? I read the documentation but it is not clear to me. Thanks

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## [JuMP-dev 2020](https://discourse.julialang.org/t/jump-dev-2020/33158)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 2\
**Last updated:** [March 16, 2020, 7:43pm UTC](https://discourse.julialang.org/t/jump-dev-2020/33158 "2020-03-16T19:43:00Z")

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Dear all, We are pleased to announce that we are now inviting talk submissions for JuMP-dev 2020, to be held June 15-17, 2020 in Louvain-la-Neuve, Belgium, in conjunction with UCLouvain. For more information on JuMP-de…

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## [Are there package or function for space-time plot showing clone mass?](https://discourse.julialang.org/t/are-there-package-or-function-for-space-time-plot-showing-clone-mass/36056)

<div class="topic-metadata">

**Author:** [@1634](https://discourse.julialang.org/u/1634)\
**Replies:** 0\
**Last updated:** [March 16, 2020, 7:16pm UTC](https://discourse.julialang.org/t/are-there-package-or-function-for-space-time-plot-showing-clone-mass/36056 "2020-03-16T19:16:31Z")

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For example. I check violin plot but it seems violin cannot collide with other color regime horizontally(each color series are independent)?

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## [VegaLite: Text labels on bar charts](https://discourse.julialang.org/t/vegalite-text-labels-on-bar-charts/36048)

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**Author:** [@hellemo](https://discourse.julialang.org/u/hellemo)\
**Replies:** 2\
**Last updated:** [March 16, 2020, 6:38pm UTC](https://discourse.julialang.org/t/vegalite-text-labels-on-bar-charts/36048 "2020-03-16T18:38:04Z")

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I can’t figure out how to show the actual values on a bar chart in VegaLite, I tried adapting the examples but clearly I don’t understand what options are necessary to achieve what I want. I’m able to do each layer more…

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## [\[ANN\] HalfEdges.jl](https://discourse.julialang.org/t/ann-halfedges-jl/36053)

<div class="topic-metadata">

**Author:** [@Orbots](https://discourse.julialang.org/u/Orbots)\
**Replies:** 0\
**Last updated:** [March 16, 2020, 6:29pm UTC](https://discourse.julialang.org/t/ann-halfedges-jl/36053 "2020-03-16T18:29:46Z")

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Pleased to announce HalfEdges.jl. A package that implements the Halfedge data structure and methods to perform common operations on it. Halfedge data structures are useful and convenient for navigating and querying a p…

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