# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1651

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

**Page:** 1652

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## [Strange memory allocation pattern for arrays of different types](https://discourse.julialang.org/t/strange-memory-allocation-pattern-for-arrays-of-different-types/45403)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 7\
**Last updated:** [August 23, 2020, 9:59am UTC](https://discourse.julialang.org/t/strange-memory-allocation-pattern-for-arrays-of-different-types/45403 "2020-08-23T09:59:54Z")

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Here is en example where I create a few arrays: module Test2 const N = 10^6 r1 = zeros(UInt8, N) d1 = ones(Float32, N) r2 = zeros(UInt8, N) d2 = ones(Float32, N) r3 = zeros(UInt8, N) d3 = ones(Float32, N) println(poi…

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## [Emit an AST as Julia code?](https://discourse.julialang.org/t/emit-an-ast-as-julia-code/45368)

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**Author:** [@stevenbarrett](https://discourse.julialang.org/u/stevenbarrett)\
**Replies:** 3\
**Last updated:** [August 23, 2020, 4:51am UTC](https://discourse.julialang.org/t/emit-an-ast-as-julia-code/45368 "2020-08-23T04:51:12Z")

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Hi there! Does anyone know if there a function or library to emit an AST as Julia code (i.e. convert an AST back into normal human-readable Julia)?

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## [Plotting vector field](https://discourse.julialang.org/t/plotting-vector-field/45393)

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**Author:** [@samerb](https://discourse.julialang.org/u/samerb)\
**Replies:** 4\
**Last updated:** [August 23, 2020, 2:28am UTC](https://discourse.julialang.org/t/plotting-vector-field/45393 "2020-08-23T02:28:26Z")

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I am trying to learn to plot a 2d vector field. I try to follow the example here. using Plots plotly() meshgrid(x, y) = (repeat(x, outer=length(y)), repeat(y, inner=length(x))) x, y = meshgrid(0.0:0.2:2.0, 0.0:0.2:2.0…

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## [Invoke user defined package functions on distributed workers](https://discourse.julialang.org/t/invoke-user-defined-package-functions-on-distributed-workers/45388)

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**Author:** [@Jack](https://discourse.julialang.org/u/Jack)\
**Replies:** 2\
**Last updated:** [August 23, 2020, 12:26am UTC](https://discourse.julialang.org/t/invoke-user-defined-package-functions-on-distributed-workers/45388 "2020-08-23T00:26:26Z")

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Greetings! I created a package ModelUtils and hope to run it in multiple workers. In this package, a function called linear\_regression being exported. The module is under src folder and has the following content modul…

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## [VS code error](https://discourse.julialang.org/t/vs-code-error/45349)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 8\
**Last updated:** [August 23, 2020, 1:07am UTC](https://discourse.julialang.org/t/vs-code-error/45349 "2020-08-23T01:07:34Z")

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I get this error when I try to run Julia REPL in VS Code (Windows 10): ERROR: LoadError: IOError: mkdir: invalid argument (EINVAL) Stacktrace: \[1\] uv\_error at .\\libuv.jl:97 \[inlined\] \[2\] mkdir(::String; mode::UInt16) …

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## [Why ∀ is an invalid character?](https://discourse.julialang.org/t/why-is-an-invalid-character/45371)

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**Author:** [@anon37204545](https://discourse.julialang.org/u/anon37204545)\
**Replies:** 7\
**Last updated:** [August 22, 2020, 11:48pm UTC](https://discourse.julialang.org/t/why-is-an-invalid-character/45371 "2020-08-22T23:48:44Z")

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It seems ∀ (\\forall) is not allowed for some reason: julia\> const ∀ = for ERROR: syntax: invalid character "∀" near column 7 Why is that? Is it just because it’s not on one of the character lists in the parser source c…

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## [Computing null space of a Flux Chain](https://discourse.julialang.org/t/computing-null-space-of-a-flux-chain/45359)

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**Author:** [@Jagirhussan](https://discourse.julialang.org/u/Jagirhussan)\
**Replies:** 8\
**Last updated:** [August 22, 2020, 11:32pm UTC](https://discourse.julialang.org/t/computing-null-space-of-a-flux-chain/45359 "2020-08-22T23:32:35Z")

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I have trained a Flux Chain with Dense layers. I would like to determine the null space (the space of input vectors for which the output is zeros(s) ) for this Chain. I am looking for a Julia like way to determine the pr…

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## [Getting the most utilization out of a GPU](https://discourse.julialang.org/t/getting-the-most-utilization-out-of-a-gpu/45340)

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**Author:** [@s-baumann](https://discourse.julialang.org/u/s-baumann)\
**Replies:** 2\
**Last updated:** [August 22, 2020, 11:02pm UTC](https://discourse.julialang.org/t/getting-the-most-utilization-out-of-a-gpu/45340 "2020-08-22T23:02:27Z")

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I am using a relatively high spec GPU (1080-TI) but cannot get it to run at utilizations of more than 5% (according to task manager). I believe that it is being used (rather than the CPU) because the “GPU memory” goes up…

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## [Conda ROOTENV path wrong](https://discourse.julialang.org/t/conda-rootenv-path-wrong/45186)

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**Author:** [@akahs](https://discourse.julialang.org/u/akahs)\
**Replies:** 2\
**Last updated:** [August 22, 2020, 10:29pm UTC](https://discourse.julialang.org/t/conda-rootenv-path-wrong/45186 "2020-08-22T22:29:24Z")

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I am using Julia 1.5, but for some reason when I look at Conda root environment in Julia, it points to an old installation, even though it has been uninstalled. Whenever I install anything through Conda they are installe…

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## [\[ANN\] SimplePlots.jl – Interactive Plots in 4 seconds or your money back](https://discourse.julialang.org/t/ann-simpleplots-jl-interactive-plots-in-4-seconds-or-your-money-back/39903)

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**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 23\
**Last updated:** [July 30, 2020, 4:11am UTC](https://discourse.julialang.org/t/ann-simpleplots-jl-interactive-plots-in-4-seconds-or-your-money-back/39903 "2020-07-30T04:11:08Z")

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Hi All, After being annoyed at Julia boot times one too many times, I decided to just build my own Plots+Interact package: SimplePlots.jl Its syntax mirrors Plots.jl and Interact.jl – it just takes 4 seconds to get to …

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## [Is there a way to include \`⅔\` in function name?](https://discourse.julialang.org/t/is-there-a-way-to-include-in-function-name/45378)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 3\
**Last updated:** [August 22, 2020, 9:47pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-include-in-function-name/45378 "2020-08-22T21:47:40Z")

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I want to define a function named ^⅔, which means using SymPy: Sym ^⅔(x::Sym) = x^(2 // 3) ^⅔(x::Number) = x^(2 / 3) That is, I need 2 // 3 for pretty-printing expressions in fractionals, but 2 / 3 for speed in real c…

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## [Unclear error](https://discourse.julialang.org/t/unclear-error/45356)

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**Author:** [@mamo](https://discourse.julialang.org/u/mamo)\
**Replies:** 2\
**Last updated:** [August 22, 2020, 7:55pm UTC](https://discourse.julialang.org/t/unclear-error/45356 "2020-08-22T19:55:42Z")

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Below, is example 6.2 from the book (Julia Programming for OR) ‘’’ import Pkg Pkg.add(“DataFrames”) Pkg.add(“CSV”) Pkg.add(“JuMP”) Pkg.add(“MathOptInterface”) Pkg.add(“GLPK”) Pkg.add(“Clp”) Pkg.activate(@DIR) Pk…

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## [Didn't there used to be a toolbar for Julia in VS code?](https://discourse.julialang.org/t/didnt-there-used-to-be-a-toolbar-for-julia-in-vs-code/45374)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 2\
**Last updated:** [August 22, 2020, 5:32pm UTC](https://discourse.julialang.org/t/didnt-there-used-to-be-a-toolbar-for-julia-in-vs-code/45374 "2020-08-22T17:32:34Z")

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I thought there used to be a toolbar. I can’t find any setting to get it back (obviously it isn’t presently displayed). Any clues? Thanks.

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## [Transliterate.jl, IsURL.jl – useful tools](https://discourse.julialang.org/t/transliterate-jl-isurl-jl-useful-tools/40951)

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**Author:** [@anon37204545](https://discourse.julialang.org/u/anon37204545)\
**Replies:** 37\
**Last updated:** [June 11, 2020, 9:07pm UTC](https://discourse.julialang.org/t/transliterate-jl-isurl-jl-useful-tools/40951 "2020-06-11T21:07:53Z")

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I created two very simple packages which may be useful to anyone working with text or links. Both are ports of two popular npm packages with slight modifications. They will be automatically merged into Julia registry in …

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## [Importing Query, getting "@replacena" not defined](https://discourse.julialang.org/t/importing-query-getting-replacena-not-defined/45299)

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**Author:** [@TheRoniOne](https://discourse.julialang.org/u/TheRoniOne)\
**Replies:** 7\
**Last updated:** [August 22, 2020, 5:20pm UTC](https://discourse.julialang.org/t/importing-query-getting-replacena-not-defined/45299 "2020-08-22T17:20:34Z")

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Hi, I’m trying to practise using Query for data cleaning and saw this simple example in the documentation of the library. using Query, DataFrames df = DataFrame(a=\[1,missing,3\], b=\[4,5,6\]) q = df |\> @replacena(0) |\> …

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## [How to find and replace (Regx) in string abcdac only 'a' who is not before 'c'?](https://discourse.julialang.org/t/how-to-find-and-replace-regx-in-string-abcdac-only-a-who-is-not-before-c/45354)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 6\
**Last updated:** [August 22, 2020, 2:11pm UTC](https://discourse.julialang.org/t/how-to-find-and-replace-regx-in-string-abcdac-only-a-who-is-not-before-c/45354 "2020-08-22T14:11:42Z")

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Ho to find and repalce (Regx) in string abcdac only a who is not before c ? Paul

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## [Understanding the notation (arr = \[1.2\], arr2=\[5, 7\])](https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363)

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**Author:** [@conditionality](https://discourse.julialang.org/u/conditionality)\
**Replies:** 1\
**Last updated:** [August 22, 2020, 12:25pm UTC](https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363 "2020-08-22T12:25:56Z")

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I’m came across a notation in the LibPQ.jl documentation: LibPQ.load!( (no\_nulls = \["foo", "baz"\], yes\_nulls = \["bar", missing\]), conn, "INSERT INTO libpqjl\_test (no\_nulls, yes\_nulls) VALUES (\\$1, \\$2);", ) …

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## [Websockets server with processed user input](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360)

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**Author:** [@KirillGerke](https://discourse.julialang.org/u/KirillGerke)\
**Replies:** 0\
**Last updated:** [August 22, 2020, 10:55am UTC](https://discourse.julialang.org/t/websockets-server-with-processed-user-input/45360 "2020-08-22T10:55:32Z")

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Dear All, I am new to web-stack programming and my naive implementation of websockets server is not working. I took chat server (chat\_explore.jl) from WebSockets.jl examples here (chat\_explore.html is needed to run the …

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## [Multiple fields per line in struct declaration](https://discourse.julialang.org/t/multiple-fields-per-line-in-struct-declaration/45345)

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**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 3\
**Last updated:** [August 22, 2020, 7:53am UTC](https://discourse.julialang.org/t/multiple-fields-per-line-in-struct-declaration/45345 "2020-08-22T07:53:21Z")

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I have a struct with many fields, which can be logically grouped, like this, but more fields: mutable struct Limits vMin::Float32 vMax::Float32 aMin::Float32 aMax::Float32 end Is there any way to write it simil…

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## [PackageCompiler.jl \`create\_app\` use path of the binary](https://discourse.julialang.org/t/packagecompiler-jl-create-app-use-path-of-the-binary/45348)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 3\
**Last updated:** [August 22, 2020, 6:47am UTC](https://discourse.julialang.org/t/packagecompiler-jl-create-app-use-path-of-the-binary/45348 "2020-08-22T06:47:09Z")

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I made an app using PackageCompiler.create\_app and it works really nice. My app requires a database which is a file, and I would like to use the file in the same folder as the binary… However when I run ~/bin/MyApp T…

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## [\[ANN\] FileTrees.jl -- easy everyday parallelism on trees of files](https://discourse.julialang.org/t/ann-filetrees-jl-easy-everyday-parallelism-on-trees-of-files/44891)

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**Author:** [@shashi](https://discourse.julialang.org/u/shashi)\
**Replies:** 34\
**Last updated:** [August 22, 2020, 6:03am UTC](https://discourse.julialang.org/t/ann-filetrees-jl-easy-everyday-parallelism-on-trees-of-files/44891 "2020-08-22T06:03:45Z")

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Hi Everyone! JuliaCon was awesome! Thanks to everyone who was a part of it! I’m excited to publish a project called FileTrees (repo, docs) that I have been working on with help from @jpsamaroo . It is a thin layer of …

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## [Why doesn't multithreading help here?](https://discourse.julialang.org/t/why-doesnt-multithreading-help-here/45286)

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**Author:** [@cgeoga](https://discourse.julialang.org/u/cgeoga)\
**Replies:** 12\
**Last updated:** [August 22, 2020, 2:44am UTC](https://discourse.julialang.org/t/why-doesnt-multithreading-help-here/45286 "2020-08-22T02:44:13Z")

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Hello— A very common computational issue for me is that I want to assemble kernel matrices with pretty expensive kernel functions. I have tried various ways to do this efficiently in parallel, but I can’t seem to write …

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## [StackOverflowError trying to fit a difference equation with Turing](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349)

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**Author:** [@arnaudmgh](https://discourse.julialang.org/u/arnaudmgh)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 11:21pm UTC](https://discourse.julialang.org/t/stackoverflowerror-trying-to-fit-a-difference-equation-with-turing/44349 "2020-08-21T23:21:51Z")

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I am trying to sample a difference equation using Turing but encounter errors. Basically, it’s a SIR model that solves fine, with a quick solver function written below (I wrote my own very simple solver to understand th…

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## [\[ANN\] JSONLines.jl ~1.0.0 and preview to 1.1.0~ 1.2.0 and preview to 1.3.0](https://discourse.julialang.org/t/ann-jsonlines-jl-1-0-0-and-preview-to-1-1-0-1-2-0-and-preview-to-1-3-0/45058)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 1\
**Last updated:** [August 21, 2020, 11:19pm UTC](https://discourse.julialang.org/t/ann-jsonlines-jl-1-0-0-and-preview-to-1-1-0-1-2-0-and-preview-to-1-3-0/45058 "2020-08-21T23:19:20Z")

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First off all, thanks to everyone who has replied to my initial post. The first version of JSONLines.jl is now in the official repository. Since registering it I have been working on a lazy reader for e.g. larger than me…

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## [CSV file reading Arrays as String in CSVFiles.jl and CSV.jl](https://discourse.julialang.org/t/csv-file-reading-arrays-as-string-in-csvfiles-jl-and-csv-jl/45331)

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**Author:** [@stochastic\_guy](https://discourse.julialang.org/u/stochastic_guy)\
**Replies:** 4\
**Last updated:** [August 21, 2020, 11:01pm UTC](https://discourse.julialang.org/t/csv-file-reading-arrays-as-string-in-csvfiles-jl-and-csv-jl/45331 "2020-08-21T23:01:53Z")

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I am trying to read a CSV file that has a column of Arrays. While reading it via CSVFiles.jl and CSV.jl the column of arrays are loaded as String. This is how that specific column values look like in the CSV File

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## [Dictionary-like data structure representing a bijective map?](https://discourse.julialang.org/t/dictionary-like-data-structure-representing-a-bijective-map/45341)

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**Author:** [@CameronBieganek](https://discourse.julialang.org/u/CameronBieganek)\
**Replies:** 1\
**Last updated:** [August 21, 2020, 10:17pm UTC](https://discourse.julialang.org/t/dictionary-like-data-structure-representing-a-bijective-map/45341 "2020-08-21T22:17:10Z")

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Does anyone know of a dictionary-like data structure that represents a bijective (one-to-one and onto) map? And if so, is there a Julia implementation of such a data structure? Ideally this data structure would have a m…

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## [Not getting inline results on VS Code similar to Juno](https://discourse.julialang.org/t/not-getting-inline-results-on-vs-code-similar-to-juno/45314)

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**Author:** [@LasseKatten](https://discourse.julialang.org/u/LasseKatten)\
**Replies:** 13\
**Last updated:** [August 21, 2020, 9:55pm UTC](https://discourse.julialang.org/t/not-getting-inline-results-on-vs-code-similar-to-juno/45314 "2020-08-21T21:55:23Z")

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Hi I recently switched from Juno to VS Code, and I’m looking for a way to replicate the following Thus far, I’ve set the results to show inline but it only appears in REPL on execution. What am I doing wrong?

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## [Was the path to Julia 1.5.0 eventually fixed?](https://discourse.julialang.org/t/was-the-path-to-julia-1-5-0-eventually-fixed/45338)

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**Author:** [@reb](https://discourse.julialang.org/u/reb)\
**Replies:** 0\
**Last updated:** [August 21, 2020, 9:24pm UTC](https://discourse.julialang.org/t/was-the-path-to-julia-1-5-0-eventually-fixed/45338 "2020-08-21T21:24:57Z")

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With the release of Julia 1.5.1 apparently imminent, I’d like to be sure that the path mistake made with 1.5.0 won’t be repeated in 1.5.1. When Julia 1.5.0 was first released, the path to Julia.exe included ‘Julia 1.5.0…

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## [Can I alias an array element to a simple name like \`x\`?](https://discourse.julialang.org/t/can-i-alias-an-array-element-to-a-simple-name-like-x/45337)

<div class="topic-metadata">

**Author:** [@NightMachinary](https://discourse.julialang.org/u/NightMachinary)\
**Replies:** 2\
**Last updated:** [August 21, 2020, 8:53pm UTC](https://discourse.julialang.org/t/can-i-alias-an-array-element-to-a-simple-name-like-x/45337 "2020-08-21T20:53:58Z")

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I want to alias some array elements to simple variable names for readability: a = collect(700:710) alias b = a\[10\] # pseudocode alias c = a\[20\] b = 6 @assert a\[10\] == 6 How can I do this? The aliases can be only in the…

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## [Adding external force RigidBodyDynamics mechansms](https://discourse.julialang.org/t/adding-external-force-rigidbodydynamics-mechansms/45233)

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**Author:** [@\_dominic](https://discourse.julialang.org/u/_dominic)\
**Replies:** 5\
**Last updated:** [August 21, 2020, 8:44pm UTC](https://discourse.julialang.org/t/adding-external-force-rigidbodydynamics-mechansms/45233 "2020-08-21T20:44:19Z")

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I am trying to figure out how to add an external force to a specific location on a rigid body. For example, From the pendulum example, I can add a point to the tip of the second link body = findbody(mechanism, "lower…

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