# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1006

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

**Page:** 1007

---

## [Julia Meetup Copenhagen August - Save the Date](https://discourse.julialang.org/t/julia-meetup-copenhagen-august-save-the-date/82955)

<div class="topic-metadata">

**Author:** [@wc4wc4wc4](https://discourse.julialang.org/u/wc4wc4wc4)\
**Replies:** 2\
**Last updated:** [June 18, 2022, 11:20pm UTC](https://discourse.julialang.org/t/julia-meetup-copenhagen-august-save-the-date/82955 "2022-06-18T23:20:59Z")

</div>

The date for the next Julia Copenhagen Meetup is the going to be the 18th of August. This time, the event will be hosted by PFA and we will hear from Niels Lykke Sørensen about the use of Julia in PFA. In case anyone e…

---

## [TypeError in Julia/Turing when sampling for a forced differential equation](https://discourse.julialang.org/t/typeerror-in-julia-turing-when-sampling-for-a-forced-differential-equation/82937)

<div class="topic-metadata">

**Author:** [@Duo\_Chan](https://discourse.julialang.org/u/Duo_Chan)\
**Replies:** 6\
**Last updated:** [June 18, 2022, 9:50pm UTC](https://discourse.julialang.org/t/typeerror-in-julia-turing-when-sampling-for-a-forced-differential-equation/82937 "2022-06-18T21:50:03Z")

</div>

Hi I am new to Julia and Turing and am trying to fit a forced 0-D box ODE to data, but I get type error when doing sampling. The tutorial (Bayesian Estimation of Differential Equations) gives an example for unforced LV…

---

## [Initialize the julia runtime more than once within C++](https://discourse.julialang.org/t/initialize-the-julia-runtime-more-than-once-within-c/82892)

<div class="topic-metadata">

**Author:** [@MarioSouto](https://discourse.julialang.org/u/MarioSouto)\
**Replies:** 5\
**Last updated:** [June 18, 2022, 7:49pm UTC](https://discourse.julialang.org/t/initialize-the-julia-runtime-more-than-once-within-c/82892 "2022-06-18T19:49:34Z")

</div>

I’m trying to create a micro service in C++ that calls julia at each new request. In the first call it works just fine but it crashes with a signal (11): Segmentation fault at the second call. I’ve tried initializing the…

---

## [@variables parsing breaks on default value?](https://discourse.julialang.org/t/variables-parsing-breaks-on-default-value/82970)

<div class="topic-metadata">

**Author:** [@dodoplus](https://discourse.julialang.org/u/dodoplus)\
**Replies:** 3\
**Last updated:** [June 18, 2022, 6:18pm UTC](https://discourse.julialang.org/t/variables-parsing-breaks-on-default-value/82970 "2022-06-18T18:18:39Z")

</div>

This code snippet: sts = @variables begin m\_flow(t), \[connect=Flow\], T(t)=T0, \[connect=Stream\] end Fails with: LoadError: AssertionError: @variables expects a tuple of expressions or an expression of a tuple (…

---

## [Unpack named tuples (does anyone know how to do it?)](https://discourse.julialang.org/t/unpack-named-tuples-does-anyone-know-how-to-do-it/32456)

<div class="topic-metadata">

**Author:** [@rvignolo](https://discourse.julialang.org/u/rvignolo)\
**Replies:** 10\
**Last updated:** [June 18, 2022, 5:38pm UTC](https://discourse.julialang.org/t/unpack-named-tuples-does-anyone-know-how-to-do-it/32456 "2022-06-18T17:38:15Z")

</div>

Hi all, I just wanted to know if it is possible to unpack named tuples in the following context. I know that Parameters.jl addresses some related issues, but I have not been able to figure out if it can handle the follo…

---

## [Interesting quote about JAX by Viral Shah in an article in Business Insider](https://discourse.julialang.org/t/interesting-quote-about-jax-by-viral-shah-in-an-article-in-business-insider/82978)

<div class="topic-metadata">

**Author:** [@akvsak](https://discourse.julialang.org/u/akvsak)\
**Replies:** 0\
**Last updated:** [June 18, 2022, 5:34pm UTC](https://discourse.julialang.org/t/interesting-quote-about-jax-by-viral-shah-in-an-article-in-business-insider/82978 "2022-06-18T17:34:28Z")

</div>

“JAX is a feat of engineering,” said Viral Shah, creator of the Julia programming language that experts frequently compare to JAX. “I think of JAX as a separate programming language that happens to be instantiated throu…

---

## [A default representation for Expr](https://discourse.julialang.org/t/a-default-representation-for-expr/82956)

<div class="topic-metadata">

**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 3\
**Last updated:** [June 18, 2022, 3:15pm UTC](https://discourse.julialang.org/t/a-default-representation-for-expr/82956 "2022-06-18T15:15:21Z")

</div>

Say I have two equivalent expressions: julia\> ex1 = :(a + b\*c + 1) :(a + b \* c + 1) julia\> ex2 = :(1 + a + c\*b) :(1 + a + c \* b) Is there a way to naively rearrange each of these to some default representation, so tha…

---

## [\[ANN\] Makie 0.17.x](https://discourse.julialang.org/t/ann-makie-0-17-x/82920)

<div class="topic-metadata">

**Author:** [@jules](https://discourse.julialang.org/u/jules)\
**Replies:** 5\
**Last updated:** [June 18, 2022, 3:21pm UTC](https://discourse.julialang.org/t/ann-makie-0-17-x/82920 "2022-06-18T15:21:38Z")

</div>

Hi everybody, The last Makie announcement post was a while ago and even if 0.17 and following patch versions have been out for a little bit, I think some changes are worth highlighting again, in no particular order: G…

---

## [Catalyst Jump model and callbacks](https://discourse.julialang.org/t/catalyst-jump-model-and-callbacks/82967)

<div class="topic-metadata">

**Author:** [@jae0](https://discourse.julialang.org/u/jae0)\
**Replies:** 7\
**Last updated:** [June 18, 2022, 1:46pm UTC](https://discourse.julialang.org/t/catalyst-jump-model-and-callbacks/82967 "2022-06-18T13:46:57Z")

</div>

Hello, this is a question that looks related to the following: I am hoping to perturb the system state at multiple times using Catalyst / DiscreteProblem / JumpProblem. I have found the above answer as well as the re…

---

## [There should be a guide for compat-block writing](https://discourse.julialang.org/t/there-should-be-a-guide-for-compat-block-writing/82963)

<div class="topic-metadata">

**Author:** [@Rratic](https://discourse.julialang.org/u/Rratic)\
**Replies:** 9\
**Last updated:** [June 18, 2022, 12:22pm UTC](https://discourse.julialang.org/t/there-should-be-a-guide-for-compat-block-writing/82963 "2022-06-18T12:22:18Z")

</div>

This afternoon (time zone: east 8), I noticed several topics in JuliaCN, all asking about package using problems. I looked at the github repos and noticed that, although packages vary in (science) fields, they aren’t abl…

---

## [How to simply get the array struct's element array](https://discourse.julialang.org/t/how-to-simply-get-the-array-structs-element-array/82965)

<div class="topic-metadata">

**Author:** [@cepheid](https://discourse.julialang.org/u/cepheid)\
**Replies:** 2\
**Last updated:** [June 18, 2022, 12:48pm UTC](https://discourse.julialang.org/t/how-to-simply-get-the-array-structs-element-array/82965 "2022-06-18T12:48:05Z")

</div>

For example: mutable struct Coords x::Float64 y::Float64 z::Float64 end n = 10 v = Vector{Coords}(undef, n) for i = 1:n v\[i\] = Coords(rand(), rand(), rand()) end I want to get ar…

---

## [Plotting on remote server](https://discourse.julialang.org/t/plotting-on-remote-server/82968)

<div class="topic-metadata">

**Author:** [@Mahmoud](https://discourse.julialang.org/u/Mahmoud)\
**Replies:** 0\
**Last updated:** [June 18, 2022, 12:47pm UTC](https://discourse.julialang.org/t/plotting-on-remote-server/82968 "2022-06-18T12:47:04Z")

</div>

I am runnging my code on supercomputer server and I always receive this error Connection refused GKS: can't connect to GKS socket application GKS: Open failed in routine OPEN\_WS GKS: GKS not in proper state. GKS must b…

---

## [Parallelizing GSA - A size issue](https://discourse.julialang.org/t/parallelizing-gsa-a-size-issue/82964)

<div class="topic-metadata">

**Author:** [@xztt](https://discourse.julialang.org/u/xztt)\
**Replies:** 1\
**Last updated:** [June 18, 2022, 12:43pm UTC](https://discourse.julialang.org/t/parallelizing-gsa-a-size-issue/82964 "2022-06-18T12:43:27Z")

</div>

Hi, I am looking to try and speed up my code and trying to following the example in the documentation here On running the below x = \[prob.u0;prob.p\] function circ(x) prob\_func(prob,i,repeat) = remake(prob;u0 = x\[1…

---

## [Discussion on improving Julia REPL for beginners](https://discourse.julialang.org/t/discussion-on-improving-julia-repl-for-beginners/82933)

<div class="topic-metadata">

**Author:** [@kdheepak](https://discourse.julialang.org/u/kdheepak)\
**Replies:** 12\
**Last updated:** [June 18, 2022, 12:39pm UTC](https://discourse.julialang.org/t/discussion-on-improving-julia-repl-for-beginners/82933 "2022-06-18T12:39:26Z")

</div>

I wanted to start a discussion on some features that I think it would be nice to have in the Julia REPL by default, and some features that exist in ipython already. Convey difference visually between input prompt, expr…

---

## [Adding seed row to empty dataframe then updating it](https://discourse.julialang.org/t/adding-seed-row-to-empty-dataframe-then-updating-it/82942)

<div class="topic-metadata">

**Author:** [@anon69491625](https://discourse.julialang.org/u/anon69491625)\
**Replies:** 5\
**Last updated:** [June 18, 2022, 12:14pm UTC](https://discourse.julialang.org/t/adding-seed-row-to-empty-dataframe-then-updating-it/82942 "2022-06-18T12:14:08Z")

</div>

I seem to be missing something here. I thought I understood how push works but obviously not. Can someone help please. I have a dataframe defined describe(df\_dash\_table) 9×7 DataFrame Row │ variable mean min …

---

## [Two Language Problem. What is it?](https://discourse.julialang.org/t/two-language-problem-what-is-it/82925)

<div class="topic-metadata">

**Author:** [@ReneganRonin](https://discourse.julialang.org/u/ReneganRonin)\
**Replies:** 7\
**Last updated:** [June 18, 2022, 11:59am UTC](https://discourse.julialang.org/t/two-language-problem-what-is-it/82925 "2022-06-18T11:59:08Z")

</div>

It has been in my mind for a while ever since I was new to the language in late 2020, and I always see the “two-language problem” in many Julia blogs and articles. With my lack of experience in software development and p…

---

## [Can't get pretty error printing in \`Meta.parse()\`](https://discourse.julialang.org/t/cant-get-pretty-error-printing-in-meta-parse/82961)

<div class="topic-metadata">

**Author:** [@AlexFreik](https://discourse.julialang.org/u/AlexFreik)\
**Replies:** 3\
**Last updated:** [June 18, 2022, 10:52am UTC](https://discourse.julialang.org/t/cant-get-pretty-error-printing-in-meta-parse/82961 "2022-06-18T10:52:27Z")

</div>

showerror doesn’t seems to work for Meta.parse(). For example, when i type 5 sin I get a nice messge. julia\> 5 sin ERROR: syntax: extra token "sin" after end of expression But if I type Meta.parse("5 sin") it doesn’t l…

---

## [How to define constraints on a collection of vectors separately?](https://discourse.julialang.org/t/how-to-define-constraints-on-a-collection-of-vectors-separately/82926)

<div class="topic-metadata">

**Author:** [@Kevin\_12](https://discourse.julialang.org/u/Kevin_12)\
**Replies:** 2\
**Last updated:** [June 18, 2022, 9:28am UTC](https://discourse.julialang.org/t/how-to-define-constraints-on-a-collection-of-vectors-separately/82926 "2022-06-18T09:28:15Z")

</div>

The original problem is so larg. But, Suppose we have this small set of vectors A = \[ \[ \[13, 48,99\] , \[71, 58, 99\]\], \[\[91, 59, 22\], \[94, 86, 22\], \[71, 58, 22\], \[19,55,22\]\], \[\[41, 79, 12\], \[23, 16, 12\],…

---

## [Interest in chemistry-focused BoF?](https://discourse.julialang.org/t/interest-in-chemistry-focused-bof/56425)

<div class="topic-metadata">

**Author:** [@rkurchin](https://discourse.julialang.org/u/rkurchin)\
**Replies:** 56\
**Last updated:** [July 27, 2021, 9:26pm UTC](https://discourse.julialang.org/t/interest-in-chemistry-focused-bof/56425 "2021-07-27T21:26:14Z")

</div>

Hey Julia fam! I was thinking that it would be cool to organize a BoF session at JuliaCon focused around folks who use Julia for chemistry- and/or materials-related things. I bounced the idea off of @tim.holy and he was…

---

## [Make Julia VSCode use Manifest.toml and Project.toml files from the folder of script being run](https://discourse.julialang.org/t/make-julia-vscode-use-manifest-toml-and-project-toml-files-from-the-folder-of-script-being-run/82046)

<div class="topic-metadata">

**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 9\
**Last updated:** [June 17, 2022, 1:32pm UTC](https://discourse.julialang.org/t/make-julia-vscode-use-manifest-toml-and-project-toml-files-from-the-folder-of-script-being-run/82046 "2022-06-17T13:32:25Z")

</div>

I have a folder with a “Manifest.toml” and a “Project.toml” file. I also have a script, “my\_julia\_script.jl”. I open the script and run some stuff. However, it seems to use the general julia environment. I want it to use…

---

## [How to make this graph more beautiful?](https://discourse.julialang.org/t/how-to-make-this-graph-more-beautiful/82912)

<div class="topic-metadata">

**Author:** [@Raymond](https://discourse.julialang.org/u/Raymond)\
**Replies:** 7\
**Last updated:** [June 18, 2022, 6:40am UTC](https://discourse.julialang.org/t/how-to-make-this-graph-more-beautiful/82912 "2022-06-18T06:40:55Z")

</div>

Dear all, I want to add annotations in scatter plot. But the annotations are very large, how to make it smaller and beautiful? julia\> using DataFrames, RDatasets, Plots julia\> df = dataset("datasets", "iris"); julia\> …

---

## [Restrict dispatch domain](https://discourse.julialang.org/t/restrict-dispatch-domain/82953)

<div class="topic-metadata">

**Author:** [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)\
**Replies:** 0\
**Last updated:** [June 18, 2022, 5:57am UTC](https://discourse.julialang.org/t/restrict-dispatch-domain/82953 "2022-06-18T05:57:35Z")

</div>

formsumf(x :: Array{T,2}, A::Array{NTuple{3,T}} ) where T\<: Number = sum(x\*mapreduce(Base.splat(Base.vect),hcat, A)) julia\> A=\[(1,2,4),(3,5,4),(3,2,1),(9,2,6),(1,1,2)\] 5-element Vector{Tuple{Int64, Int64, Int64}}: (…

---

## [Automatic differentiation and Trapz](https://discourse.julialang.org/t/automatic-differentiation-and-trapz/82135)

<div class="topic-metadata">

**Author:** [@chupin](https://discourse.julialang.org/u/chupin)\
**Replies:** 10\
**Last updated:** [June 18, 2022, 5:53am UTC](https://discourse.julialang.org/t/automatic-differentiation-and-trapz/82135 "2022-06-18T05:53:18Z")

</div>

It seems that Nonconvex is not able to deal with the trapz function, but maybe, I’ve done something wrong. The code (that is a nonsense toy code) : using Nonconvex Nonconvex.@load Ipopt using Trapz function obj(hV,N,M)…

---

## [What is the difference between \`using Plots; gr()\` and "using GR"?](https://discourse.julialang.org/t/what-is-the-difference-between-using-plots-gr-and-using-gr/82947)

<div class="topic-metadata">

**Author:** [@Raymond](https://discourse.julialang.org/u/Raymond)\
**Replies:** 2\
**Last updated:** [June 18, 2022, 5:44am UTC](https://discourse.julialang.org/t/what-is-the-difference-between-using-plots-gr-and-using-gr/82947 "2022-06-18T05:44:16Z")

</div>

Dear all, we can use GR backend, using Plots gr() we can also directly use using GR So what is the difference between two kinds of code?

---

## [Xpress Julia API has bug with fixing variables](https://discourse.julialang.org/t/xpress-julia-api-has-bug-with-fixing-variables/82895)

<div class="topic-metadata">

**Author:** [@Popeye](https://discourse.julialang.org/u/Popeye)\
**Replies:** 5\
**Last updated:** [June 18, 2022, 5:38am UTC](https://discourse.julialang.org/t/xpress-julia-api-has-bug-with-fixing-variables/82895 "2022-06-18T05:38:40Z")

</div>

Fixing variables does not seems to be working with the Xpress solver. I used the example below (which was posted by someone on this forum) to create this MWE. I fix one of the variables as zero but it seems like JuMP is…

---

## [HPC 12M Master course at Sissa, Trieste, Italy](https://discourse.julialang.org/t/hpc-12m-master-course-at-sissa-trieste-italy/82924)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [June 18, 2022, 5:15am UTC](https://discourse.julialang.org/t/hpc-12m-master-course-at-sissa-trieste-italy/82924 "2022-06-18T05:15:53Z")

</div>

Hello, I forward this email on an (advanced) 12 months master course on HPC programming/hardware at SISSA in Trieste, Italy (they are pretty strong in Physics)… 17/06/2022 Dear Users, you might be interested to know a…

---

## [Extract a field from an array of structures](https://discourse.julialang.org/t/extract-a-field-from-an-array-of-structures/82916)

<div class="topic-metadata">

**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 7\
**Last updated:** [June 17, 2022, 11:50pm UTC](https://discourse.julialang.org/t/extract-a-field-from-an-array-of-structures/82916 "2022-06-17T23:50:03Z")

</div>

I was wondering if there is a more elegent way to extract a field from an array of structures. An example follows: julia\> struct Foo i::Int v::Vector{Int} end julia\> foo = Vector{Foo}(und…

---

## [Change of internal energy with time-variable mass](https://discourse.julialang.org/t/change-of-internal-energy-with-time-variable-mass/82509)

<div class="topic-metadata">

**Author:** [@asprionj](https://discourse.julialang.org/u/asprionj)\
**Replies:** 16\
**Last updated:** [June 17, 2022, 5:01pm UTC](https://discourse.julialang.org/t/change-of-internal-energy-with-time-variable-mass/82509 "2022-06-17T17:01:28Z")

</div>

I hope there’s a thermodynamic superhero to the rescue… :wink: The problem seems simple. There’s an open control volume (of fixed volume), filled with an incompressible fluid, that changes its density with temperature. …

---

## [SubString doesn't work with unicode](https://discourse.julialang.org/t/substring-doesnt-work-with-unicode/40976)

<div class="topic-metadata">

**Author:** [@nicolas](https://discourse.julialang.org/u/nicolas)\
**Replies:** 13\
**Last updated:** [June 17, 2022, 10:07pm UTC](https://discourse.julialang.org/t/substring-doesnt-work-with-unicode/40976 "2022-06-17T22:07:33Z")

</div>

It seems SubString works well with standard characters, but not for unicode characters. Below is an example in Julia 1.4.2: julia\> SubString("aaaa",1,2) "aa" julia\> SubString("αααα",1,2) ERROR: StringIndexError("αααα",…

---

## [Creating sliders for parameters of reaction network to make interactive plot](https://discourse.julialang.org/t/creating-sliders-for-parameters-of-reaction-network-to-make-interactive-plot/82940)

<div class="topic-metadata">

**Author:** [@Dragolonth](https://discourse.julialang.org/u/Dragolonth)\
**Replies:** 1\
**Last updated:** [June 17, 2022, 9:32pm UTC](https://discourse.julialang.org/t/creating-sliders-for-parameters-of-reaction-network-to-make-interactive-plot/82940 "2022-06-17T21:32:25Z")

</div>

I currently have a reaction network defined using Catalyst.jl and was wondering what the best way would be to create interactive sliders for the parameters. My goal is to observe how the plotted trajectories shift as I a…

[Previous page](https://discourse.julialang.org/latest.md?page=1005)

[Next page](https://discourse.julialang.org/latest.md?page=1007)