# Latest

**URL:** https://discourse.julialang.org/latest.md?page=895

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

**Page:** 896

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## [\[WIP\] MPISort.jl - Distributed MPI Sorting Algorithms. Suggestions welcome!](https://discourse.julialang.org/t/wip-mpisort-jl-distributed-mpi-sorting-algorithms-suggestions-welcome/88730)

<div class="topic-metadata">

**Author:** [@anicusan](https://discourse.julialang.org/u/anicusan)\
**Replies:** 2\
**Last updated:** [October 14, 2022, 2:24pm UTC](https://discourse.julialang.org/t/wip-mpisort-jl-distributed-mpi-sorting-algorithms-suggestions-welcome/88730 "2022-10-14T14:24:34Z")

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Hi all, It was with great horror that I discovered how non-trivial sorting N elements across P clusters without any one cluster being able to hold all elements at once was. Or maybe I’m just thick. Anyways, I only found…

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## [LibGit2/libgit2 is failing while doing tests for v1.8.2](https://discourse.julialang.org/t/libgit2-libgit2-is-failing-while-doing-tests-for-v1-8-2/88727)

<div class="topic-metadata">

**Author:** [@Vinod\_Kumar\_K](https://discourse.julialang.org/u/Vinod_Kumar_K)\
**Replies:** 1\
**Last updated:** [October 14, 2022, 1:26pm UTC](https://discourse.julialang.org/t/libgit2-libgit2-is-failing-while-doing-tests-for-v1-8-2/88727 "2022-10-14T13:26:36Z")

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LibGit2/libgit2 (1) | failed at 2022-10-14T10:40:41.483 Test Failed at /julia/juliabuild/usr/share/julia/stdlib/v1.8/LibGit2/test/libgit2.jl:3181 Expression: err.code == LibGit2.Error.ECERTIFICATE Evaluated: …

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## [Reduce DataFrame by unique value](https://discourse.julialang.org/t/reduce-dataframe-by-unique-value/88723)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 5\
**Last updated:** [October 14, 2022, 12:09pm UTC](https://discourse.julialang.org/t/reduce-dataframe-by-unique-value/88723 "2022-10-14T12:09:35Z")

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Hi all, I have a large DataFrame with a column of values and a unique id. I would like to create a new DataFrame of the unique values in one column, and a vector of the corresponding ids in another column. Here is an ex…

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## [Looking for ONE package, to do BASIC number formatting for console-text-output](https://discourse.julialang.org/t/looking-for-one-package-to-do-basic-number-formatting-for-console-text-output/88655)

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**Author:** [@fins](https://discourse.julialang.org/u/fins)\
**Replies:** 21\
**Last updated:** [October 14, 2022, 12:08pm UTC](https://discourse.julialang.org/t/looking-for-one-package-to-do-basic-number-formatting-for-console-text-output/88655 "2022-10-14T12:08:42Z")

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Hi, I’ve recently explored a lot of packages to get more of an idea, of what kind of functionality is being covered in the julia-ecosystem, as it applies to my needs. While there are some very nice and powerful package…

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## [GLMakie. 2D textured Plane in 3D space](https://discourse.julialang.org/t/glmakie-2d-textured-plane-in-3d-space/88668)

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**Author:** [@LeN3rd](https://discourse.julialang.org/u/LeN3rd)\
**Replies:** 5\
**Last updated:** [October 14, 2022, 11:20am UTC](https://discourse.julialang.org/t/glmakie-2d-textured-plane-in-3d-space/88668 "2022-10-14T11:20:45Z")

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This might be a stupid question, but i want to have a simple 2d textured plane that sits in 3d space, rendered with Makie. Eventually there should be more complex 3D Meshes, but for now i struggle to even get a textured …

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## [Group by Multi Column Dataframe to share ID? Maybe?](https://discourse.julialang.org/t/group-by-multi-column-dataframe-to-share-id-maybe/88692)

<div class="topic-metadata">

**Author:** [@theboiwholived](https://discourse.julialang.org/u/theboiwholived)\
**Replies:** 6\
**Last updated:** [October 14, 2022, 11:37am UTC](https://discourse.julialang.org/t/group-by-multi-column-dataframe-to-share-id-maybe/88692 "2022-10-14T11:37:04Z")

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Hey ladies and gents! I’ve been searching high and low for the best way to do a multi column groupby, i think. Essentially i have a dataframe. with a multitude of columns but only 2 that matter in this contex. I do a …

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## [Is there a way to force modification of the binded object instead of rebind to a new object?](https://discourse.julialang.org/t/is-there-a-way-to-force-modification-of-the-binded-object-instead-of-rebind-to-a-new-object/88724)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [October 14, 2022, 11:35am UTC](https://discourse.julialang.org/t/is-there-a-way-to-force-modification-of-the-binded-object-instead-of-rebind-to-a-new-object/88724 "2022-10-14T11:35:37Z")

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When you have a variable that points to a mutable object and you use the equal operator, Julia will simply rebind that variable to the new object. For example, in the following snippet, the objects binded by a and b do …

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## [Best practices for dealing with \`Union{Nothing,...}\`](https://discourse.julialang.org/t/best-practices-for-dealing-with-union-nothing/27402)

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**Author:** [@banbh](https://discourse.julialang.org/u/banbh)\
**Replies:** 16\
**Last updated:** [October 14, 2022, 11:03am UTC](https://discourse.julialang.org/t/best-practices-for-dealing-with-union-nothing/27402 "2022-10-14T11:03:42Z")

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I’d like learn how to write good code that deals with Union{Nothing,...}. For example what’s the right way to pattern-match a value of this type in such a way that the compiler can infer what all the types are? For examp…

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## [Any good online resource to learn SQL?](https://discourse.julialang.org/t/any-good-online-resource-to-learn-sql/88533)

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**Author:** [@fksayaci](https://discourse.julialang.org/u/fksayaci)\
**Replies:** 3\
**Last updated:** [October 14, 2022, 10:49am UTC](https://discourse.julialang.org/t/any-good-online-resource-to-learn-sql/88533 "2022-10-14T10:49:08Z")

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Hello all, I have a simple and off-topic question. This platform has been very useful for me to overcome the challenges in my Julia projects. That is why I wanted to ask this question here. If you think that my question…

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## [Optimization.jl constraints violated...why?](https://discourse.julialang.org/t/optimization-jl-constraints-violated-why/88269)

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**Author:** [@kjohnsen](https://discourse.julialang.org/u/kjohnsen)\
**Replies:** 8\
**Last updated:** [October 14, 2022, 10:38am UTC](https://discourse.julialang.org/t/optimization-jl-constraints-violated-why/88269 "2022-10-14T10:38:34Z")

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I am trying to implement model predictive control using Optimization.jl, with the Optim backend. It seems like it should be straightforward: a quadratic program, with some linear constraints. But the constraints just are…

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## [Classifiers - Development Status for packages](https://discourse.julialang.org/t/classifiers-development-status-for-packages/88722)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 0\
**Last updated:** [October 14, 2022, 10:15am UTC](https://discourse.julialang.org/t/classifiers-development-status-for-packages/88722 "2022-10-14T10:15:41Z")

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There are basically no requirements to register a Julia package (and I believe that’s a good thing), besides having an OSI-approved license. I do see for Python, in PyPI there’s (and I suggest the same for Julia): 1 - …

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## [JuliaCall segmentation fault](https://discourse.julialang.org/t/juliacall-segmentation-fault/80208)

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**Author:** [@cjproud](https://discourse.julialang.org/u/cjproud)\
**Replies:** 5\
**Last updated:** [October 14, 2022, 9:47am UTC](https://discourse.julialang.org/t/juliacall-segmentation-fault/80208 "2022-10-14T09:47:06Z")

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I’ve got a Julia module (which contains compiled Fortran code) which is called in Python using JuliaCall (Guide · PythonCall & JuliaCall), for example within a Python script: from juliacall import Main as jl jl.seval(us…

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## [Julia-vim and rainbow brackets](https://discourse.julialang.org/t/julia-vim-and-rainbow-brackets/57180)

<div class="topic-metadata">

**Author:** [@imLew](https://discourse.julialang.org/u/imLew)\
**Replies:** 1\
**Last updated:** [October 14, 2022, 9:19am UTC](https://discourse.julialang.org/t/julia-vim-and-rainbow-brackets/57180 "2022-10-14T09:19:47Z")

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I’m using julia-vim for syntax highlighting and unicode support in vim and it’s great. I would also like to use rainbow brackets (eg this plugin), but it doesn’t work within julia blocks (e.g. function..end, begin...end)…

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## [JuliaHub Documentation Build Question](https://discourse.julialang.org/t/juliahub-documentation-build-question/88703)

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**Author:** [@AP6YC](https://discourse.julialang.org/u/AP6YC)\
**Replies:** 1\
**Last updated:** [October 14, 2022, 9:10am UTC](https://discourse.julialang.org/t/juliahub-documentation-build-question/88703 "2022-10-14T09:10:25Z")

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I have been building documentation for my Julia package via GitHub actions for a while now, but I have noticed that JuliaHub registered packages also have JuliaHub-hosted documentation. Because I cannot for the life of m…

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## [Single string on multiple lines without \`\\n\`](https://discourse.julialang.org/t/single-string-on-multiple-lines-without-n/18099)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 6\
**Last updated:** [October 14, 2022, 9:09am UTC](https://discourse.julialang.org/t/single-string-on-multiple-lines-without-n/18099 "2022-10-14T09:09:14Z")

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Is there a way to continue a single string on multiple lines without inserting \\n into the string? For example "a#some character here b" "ab" The only methods I currently know of is string("a", "b") I was wonder…

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## [Where are Julia packages installed?](https://discourse.julialang.org/t/where-are-julia-packages-installed/88710)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 5\
**Last updated:** [October 14, 2022, 8:50am UTC](https://discourse.julialang.org/t/where-are-julia-packages-installed/88710 "2022-10-14T08:50:44Z")

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I occasionally find myself wondering where packages are installed and fail to easily find the answer, so I’m putting it here.

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## [Convert integer to bits array](https://discourse.julialang.org/t/convert-integer-to-bits-array/26663)

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**Author:** [@Kenneth\_Steimel](https://discourse.julialang.org/u/Kenneth_Steimel)\
**Replies:** 12\
**Last updated:** [October 14, 2022, 8:03am UTC](https://discourse.julialang.org/t/convert-integer-to-bits-array/26663 "2022-10-14T08:03:41Z")

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I’m trying to find a way to convert an unsigned integer value into a bitmask. Does anyone know of a way to do this efficiently using the standard library? For example, I want something to do the following: input = UIn…

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## [TemporalGPs precise zero estimate](https://discourse.julialang.org/t/temporalgps-precise-zero-estimate/87775)

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**Author:** [@jar1](https://discourse.julialang.org/u/jar1)\
**Replies:** 7\
**Last updated:** [October 14, 2022, 7:48am UTC](https://discourse.julialang.org/t/temporalgps-precise-zero-estimate/87775 "2022-10-14T07:48:09Z")

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Hi @willtebbutt I’m trying to use TemporalGPs and I wonder if you might have a moment to address an issue I’m having. The data have about 460 observations for each of 15 values of x, for a total of about 6900 observatio…

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## [I've installed juliaup from the MS store, but it's not in PATH](https://discourse.julialang.org/t/ive-installed-juliaup-from-the-ms-store-but-its-not-in-path/77809)

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**Author:** [@ultrapoci](https://discourse.julialang.org/u/ultrapoci)\
**Replies:** 6\
**Last updated:** [October 14, 2022, 5:22am UTC](https://discourse.julialang.org/t/ive-installed-juliaup-from-the-ms-store-but-its-not-in-path/77809 "2022-10-14T05:22:07Z")

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According to the Github repository, if I install juliaup from the Microsoft store, using the link provided in the repository page, both julia and juliaup should be present in PATH. But instead, none of them is available.…

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## [Nested expressions rules seem different when \`$\` involved](https://discourse.julialang.org/t/nested-expressions-rules-seem-different-when-involved/82732)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 2\
**Last updated:** [October 14, 2022, 2:51am UTC](https://discourse.julialang.org/t/nested-expressions-rules-seem-different-when-involved/82732 "2022-10-14T02:51:56Z")

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So normally when nesting an expression into an expression, it seems like it doesn’t matter if the latter is written as a quoted :( \_\_\_ ) or an Expr(:quote, \_\_\_ ). There’s a difference when the former is written as a quo…

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## [Sum of JuMP.value](https://discourse.julialang.org/t/sum-of-jump-value/88673)

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**Author:** [@Emma456](https://discourse.julialang.org/u/Emma456)\
**Replies:** 5\
**Last updated:** [October 14, 2022, 2:14am UTC](https://discourse.julialang.org/t/sum-of-jump-value/88673 "2022-10-14T02:14:36Z")

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Hello, I would like to display in an excel document the sum of students assigned for each course: if JuMP.value.(x\[i,j\])==1 for each j, display the sum of x\[i,j\] Could someone help me?

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## [Create specific excel table](https://discourse.julialang.org/t/create-specific-excel-table/88471)

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**Author:** [@Emma456](https://discourse.julialang.org/u/Emma456)\
**Replies:** 1\
**Last updated:** [October 14, 2022, 2:04am UTC](https://discourse.julialang.org/t/create-specific-excel-table/88471 "2022-10-14T02:04:38Z")

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My problem is assigning employees to offices. I would like to post the solution in an excel file, in this form: At the moment my code looks like this: XLSX.openxlsx("choix élèves julia.xlsx", mode="rw") do xf !X…

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## [Variable is not a function of independent variable error for trivial example](https://discourse.julialang.org/t/variable-is-not-a-function-of-independent-variable-error-for-trivial-example/88669)

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**Author:** [@drandran12](https://discourse.julialang.org/u/drandran12)\
**Replies:** 1\
**Last updated:** [October 13, 2022, 11:44pm UTC](https://discourse.julialang.org/t/variable-is-not-a-function-of-independent-variable-error-for-trivial-example/88669 "2022-10-13T23:44:39Z")

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I am trying out the ModelingToolkit.jl package and I get this weird error when defing the classical harmonic oscillator with the following code using ModelingToolkit, @variables t x(t) @parameters ω₀ Dₜ = Differential(t…

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## [SatelliteToolbox vs AstroLib](https://discourse.julialang.org/t/satellitetoolbox-vs-astrolib/88672)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 1\
**Last updated:** [October 13, 2022, 11:11pm UTC](https://discourse.julialang.org/t/satellitetoolbox-vs-astrolib/88672 "2022-10-13T23:11:15Z")

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I was surprised to find zero posts about the intersect between these two packages. Any overlap worth comparing, mentioning, etc? I’m mostly interested in the azimuth of the sun and moon at specific elevations (for speci…

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## [Multithreading & Ccall & WIGXJPF](https://discourse.julialang.org/t/multithreading-ccall-wigxjpf/88697)

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**Author:** [@wes648](https://discourse.julialang.org/u/wes648)\
**Replies:** 0\
**Last updated:** [October 13, 2022, 10:39pm UTC](https://discourse.julialang.org/t/multithreading-ccall-wigxjpf/88697 "2022-10-13T22:39:15Z")

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Hello! I’m trying to modify the WIGXJPF.jl wrapper to make it work with multithreading. Using the code pretty much as is (just adjusting for my personal paths), I get an error reading wigxjpf: Temp array not allocated…

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## [Apply dictionary (Dict) to many keys at once (broadcast)](https://discourse.julialang.org/t/apply-dictionary-dict-to-many-keys-at-once-broadcast/88674)

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**Author:** [@dorn-gerhard](https://discourse.julialang.org/u/dorn-gerhard)\
**Replies:** 3\
**Last updated:** [October 13, 2022, 9:51pm UTC](https://discourse.julialang.org/t/apply-dictionary-dict-to-many-keys-at-once-broadcast/88674 "2022-10-13T21:51:15Z")

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Given a simple dictionary d = Dict(1 =\> "a", 2 =\> "b", 3 =\> "c") Is there a simple way to apply the dictionary to a list / vector / tuple of keys at once? I would like to “translate” a vector of numbers into letters li…

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## [ForwardDiff yields incorrect results if one misues \`DiffCache\`](https://discourse.julialang.org/t/forwarddiff-yields-incorrect-results-if-one-misues-diffcache/88684)

<div class="topic-metadata">

**Author:** [@cuihantao](https://discourse.julialang.org/u/cuihantao)\
**Replies:** 1\
**Last updated:** [October 13, 2022, 9:34pm UTC](https://discourse.julialang.org/t/forwarddiff-yields-incorrect-results-if-one-misues-diffcache/88684 "2022-10-13T21:34:09Z")

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I’d like to report a mistake that some new users like me might make when using PreallocationTools. One should not use DiffCache to store non-variables such as parameters. It makes perfect sense in a hindsight, because th…

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## [How to increase the padding between xticks and xtick labels?](https://discourse.julialang.org/t/how-to-increase-the-padding-between-xticks-and-xtick-labels/88675)

<div class="topic-metadata">

**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 3\
**Last updated:** [October 13, 2022, 8:38pm UTC](https://discourse.julialang.org/t/how-to-increase-the-padding-between-xticks-and-xtick-labels/88675 "2022-10-13T20:38:26Z")

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I have a problem, that xticks and xtick labels almost overlap if the ticks face outwards. (It is probably because my xtick labels are like \\frac{\\pi k}{N}). How do I increase the padding between the xticks and xtick l…

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## [Invalid subtyping: can only subtype data types (related to symbolics too)](https://discourse.julialang.org/t/invalid-subtyping-can-only-subtype-data-types-related-to-symbolics-too/88683)

<div class="topic-metadata">

**Author:** [@Krastanov](https://discourse.julialang.org/u/Krastanov)\
**Replies:** 6\
**Last updated:** [October 13, 2022, 8:17pm UTC](https://discourse.julialang.org/t/invalid-subtyping-can-only-subtype-data-types-related-to-symbolics-too/88683 "2022-10-13T20:17:55Z")

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Edit: it was just a syntax error, that is being reported a bit misleadingly and led me astray I was playing with defining convoluted types and stumbled upon this behavior: julia\> struct S{T} \<: AbstractVector{T} where …

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## [Dicts with more than one key?](https://discourse.julialang.org/t/dicts-with-more-than-one-key/88680)

<div class="topic-metadata">

**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 5\
**Last updated:** [October 13, 2022, 7:22pm UTC](https://discourse.julialang.org/t/dicts-with-more-than-one-key/88680 "2022-10-13T19:22:59Z")

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Is there a standard way to create a Dict with more than one key? Or one needs to unavoidably create multiple Dicts by hand? Something like (I’m inventing here the notation): letters = Dict{Keys{Char,Char},String}( …

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