# Latest

**URL:** https://discourse.julialang.org/latest.md?page=261

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

**Page:** 262

---

## [How to use OpenCV.jl's calibrateCamera correctly?](https://discourse.julialang.org/t/how-to-use-opencv-jls-calibratecamera-correctly/113765)

<div class="topic-metadata">

**Author:** [@Kadii](https://discourse.julialang.org/u/Kadii)\
**Replies:** 6\
**Last updated:** [December 4, 2024, 11:46pm UTC](https://discourse.julialang.org/t/how-to-use-opencv-jls-calibratecamera-correctly/113765 "2024-12-04T23:46:50Z")

</div>

Hi, I’m trying to reproduce :OpenCV: Camera Calibration using OpenCV.jl. I made some adjustments but could not figure out how to properly pass the arguments to cv.calibrateCamera. 1st and 2nd arguments I passed were Ve…

---

## [Numpy.sort vs Julia sort](https://discourse.julialang.org/t/numpy-sort-vs-julia-sort/123421)

<div class="topic-metadata">

**Author:** [@gitboy16](https://discourse.julialang.org/u/gitboy16)\
**Replies:** 10\
**Last updated:** [December 4, 2024, 10:17pm UTC](https://discourse.julialang.org/t/numpy-sort-vs-julia-sort/123421 "2024-12-04T22:17:08Z")

</div>

I recently tried numpy.sort and it is really fast for a vector of 100 millions floats. It seems to be parallelized by default and/or using AVX-512. It is like 5 times faster on my system. If someone has a benchmark vs J…

---

## [How to apply a butterworth filter in a loop?](https://discourse.julialang.org/t/how-to-apply-a-butterworth-filter-in-a-loop/122818)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 6\
**Last updated:** [December 4, 2024, 7:16pm UTC](https://discourse.julialang.org/t/how-to-apply-a-butterworth-filter-in-a-loop/122818 "2024-12-04T19:16:08Z")

</div>

I constructed a Butterworth filter, which works fine: using ControlPlots, DSP # Define the cut-off frequency in Hz cut\_off\_freq = 2.0 Wn = cut\_off\_freq # Define the sampling time in seconds dt = 0.05 fs = 1/dt sim\_tim…

---

## [Parse json to vector{T} for known T](https://discourse.julialang.org/t/parse-json-to-vector-t-for-known-t/123469)

<div class="topic-metadata">

**Author:** [@kingoslo](https://discourse.julialang.org/u/kingoslo)\
**Replies:** 1\
**Last updated:** [December 4, 2024, 8:07pm UTC](https://discourse.julialang.org/t/parse-json-to-vector-t-for-known-t/123469 "2024-12-04T20:07:06Z")

</div>

Am trying to use the JSON package to parse “\[1,2,3\]” to a vector{Int64}. I notice that the parse method has optional arguments dicttype and inttype. But it seems that whatever I give as as dicttype and inttype the funct…

---

## [How to use \`readdlm\` to read in a Matrix{Char}](https://discourse.julialang.org/t/how-to-use-readdlm-to-read-in-a-matrix-char/123464)

<div class="topic-metadata">

**Author:** [@jling](https://discourse.julialang.org/u/jling)\
**Replies:** 2\
**Last updated:** [December 4, 2024, 7:40pm UTC](https://discourse.julialang.org/t/how-to-use-readdlm-to-read-in-a-matrix-char/123464 "2024-12-04T19:40:28Z")

</div>

Sometimes it’s useful to read in the file as a matrix of characters, in other words, split on empty char – but currently, readdlm(path, dlm::Char) the second argument has to be a Char and there’s no empty Char. am I miss…

---

## [Showing list of package changes?](https://discourse.julialang.org/t/showing-list-of-package-changes/123462)

<div class="topic-metadata">

**Author:** [@dgleich](https://discourse.julialang.org/u/dgleich)\
**Replies:** 2\
**Last updated:** [December 4, 2024, 4:37pm UTC](https://discourse.julialang.org/t/showing-list-of-package-changes/123462 "2024-12-04T16:37:12Z")

</div>

Is there any way to get the list of package changes in response to changing to a new version that would occur without actually changing them? (i.e. a “dry-run” option?) For instance, if I have a large project and do: (…

---

## [Passing GMP variables from C(++) to Julia](https://discourse.julialang.org/t/passing-gmp-variables-from-c-to-julia/123167)

<div class="topic-metadata">

**Author:** [@Questioner](https://discourse.julialang.org/u/Questioner)\
**Replies:** 9\
**Last updated:** [December 4, 2024, 3:38pm UTC](https://discourse.julialang.org/t/passing-gmp-variables-from-c-to-julia/123167 "2024-12-04T15:38:07Z")

</div>

Hello there, let me start by thanking the entirely altruistic help; in the long run, I hope to contribute to Julia myself. Unfortunately, I’ve run into another issue: I’d like to convert a GNU MP type (such as mpz\_t) i…

---

## [When should I define my own \`deepcopy\` and \`copy\` functions for types, if ever?](https://discourse.julialang.org/t/when-should-i-define-my-own-deepcopy-and-copy-functions-for-types-if-ever/123447)

<div class="topic-metadata">

**Author:** [@world-peace](https://discourse.julialang.org/u/world-peace)\
**Replies:** 10\
**Last updated:** [December 4, 2024, 3:24pm UTC](https://discourse.julialang.org/t/when-should-i-define-my-own-deepcopy-and-copy-functions-for-types-if-ever/123447 "2024-12-04T15:24:52Z")

</div>

Just wanted to understand if I should define deepcopy and copy for my own types, if at all. Looking at the code suggests to me deepcopy is automatic, and therefore there is generally no need to define it for user define…

---

## [Cmdline option/shortcut for activate --temp?](https://discourse.julialang.org/t/cmdline-option-shortcut-for-activate-temp/53956)

<div class="topic-metadata">

**Author:** [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Replies:** 6\
**Last updated:** [December 4, 2024, 3:12pm UTC](https://discourse.julialang.org/t/cmdline-option-shortcut-for-activate-temp/53956 "2024-12-04T15:12:02Z")

</div>

Do we have a command line option to start julia with a temporary environment, instead of having to manually \] activate --temp? I imagine something like julia --project=@temp. If not, what do you think, should we add some…

---

## [Upcoming video call: Improving Base IO](https://discourse.julialang.org/t/upcoming-video-call-improving-base-io/123171)

<div class="topic-metadata">

**Author:** [@jakobnissen](https://discourse.julialang.org/u/jakobnissen)\
**Replies:** 1\
**Last updated:** [December 4, 2024, 3:01pm UTC](https://discourse.julialang.org/t/upcoming-video-call-improving-base-io/123171 "2024-12-04T15:01:02Z")

</div>

Dear all, The abstractions around IO in Base Julia could use some improvements. Therefore, we have organised a video call meeting to discuss what can be done about it. Anyone interested is welcome to join! I will post m…

---

## [Optimization problem inside \`ODESystem\`](https://discourse.julialang.org/t/optimization-problem-inside-odesystem/123445)

<div class="topic-metadata">

**Author:** [@Sushrut\_Deshpande](https://discourse.julialang.org/u/Sushrut_Deshpande)\
**Replies:** 2\
**Last updated:** [December 4, 2024, 2:58pm UTC](https://discourse.julialang.org/t/optimization-problem-inside-odesystem/123445 "2024-12-04T14:58:55Z")

</div>

Hello, I am trying to solve an optimization problem with the variables of an ODESystem. I have a toy code below: using ModelingToolkit, DifferentialEquations, Optimization, OptimizationOptimJL,ForwardDiff, Optim using …

---

## [Excel's pivot table equivalent with DataFramesMeta](https://discourse.julialang.org/t/excels-pivot-table-equivalent-with-dataframesmeta/123456)

<div class="topic-metadata">

**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 2\
**Last updated:** [December 4, 2024, 2:44pm UTC](https://discourse.julialang.org/t/excels-pivot-table-equivalent-with-dataframesmeta/123456 "2024-12-04T14:44:33Z")

</div>

Hello, So I have a table like df = DataFrame(a= \[1,1,2,2\], b = \[1,2,1,2\], c = \[1,2,3,4\]) And I would like to create a table that, if I were to work in Excel, I could obtain with a pivot table with a for the Rows and b …

---

## [Indexing a residual of an InitializationProblem](https://discourse.julialang.org/t/indexing-a-residual-of-an-initializationproblem/123356)

<div class="topic-metadata">

**Author:** [@Bart\_van\_de\_Lint](https://discourse.julialang.org/u/Bart_van_de_Lint)\
**Replies:** 3\
**Last updated:** [December 4, 2024, 2:11pm UTC](https://discourse.julialang.org/t/indexing-a-residual-of-an-initializationproblem/123356 "2024-12-04T14:11:42Z")

</div>

I want to check the residual of the solution of an initializationproblem as done in this example: Initialization of ODESystems · ModelingToolkit.jl However, my model is quite a bit more complex than the one in the examp…

---

## [Arbitrary \`:meta\` expression AST nodes for a linter](https://discourse.julialang.org/t/arbitrary-meta-expression-ast-nodes-for-a-linter/123455)

<div class="topic-metadata">

**Author:** [@0x0f0f0f](https://discourse.julialang.org/u/0x0f0f0f)\
**Replies:** 0\
**Last updated:** [December 4, 2024, 2:09pm UTC](https://discourse.julialang.org/t/arbitrary-meta-expression-ast-nodes-for-a-linter/123455 "2024-12-04T14:09:47Z")

</div>

I’m building some tooling that performs static analysis of Julia code, which is similar to eslint in some ways. It’s currently using Expr and Expronicon.jl for parsing and pattern matching with MLStyle.jl. Let’s call it C…

---

## [Embedding Julia and multiple foreign threads](https://discourse.julialang.org/t/embedding-julia-and-multiple-foreign-threads/123394)

<div class="topic-metadata">

**Author:** [@peremato](https://discourse.julialang.org/u/peremato)\
**Replies:** 3\
**Last updated:** [December 4, 2024, 1:51pm UTC](https://discourse.julialang.org/t/embedding-julia-and-multiple-foreign-threads/123394 "2024-12-04T13:51:14Z")

</div>

The embedding documentation says clearly that you can only use the functions jl\_...() from a single foreign thread in which you have called jl\_init(). The question is, has anything changed with respect this restriction i…

---

## [Daytona.io - an open-source Development Environment Manager - Julia usage?](https://discourse.julialang.org/t/daytona-io-an-open-source-development-environment-manager-julia-usage/123011)

<div class="topic-metadata">

**Author:** [@scelles](https://discourse.julialang.org/u/scelles)\
**Replies:** 3\
**Last updated:** [December 4, 2024, 12:01pm UTC](https://discourse.julialang.org/t/daytona-io-an-open-source-development-environment-manager-julia-usage/123011 "2024-12-04T12:01:40Z")

</div>

Hello, I recently read a LinkedIn post about Daytona.io. Daytona.io is an open-source Development Environment Manager designed to simplify and streamline the process of setting up development environments\[1\]\[3\]. Key fe…

---

## [Adding \[sources\] information for a dependency which is in a subdirectory](https://discourse.julialang.org/t/adding-sources-information-for-a-dependency-which-is-in-a-subdirectory/121104)

<div class="topic-metadata">

**Author:** [@SamBrand](https://discourse.julialang.org/u/SamBrand)\
**Replies:** 5\
**Last updated:** [December 4, 2024, 11:39am UTC](https://discourse.julialang.org/t/adding-sources-information-for-a-dependency-which-is-in-a-subdirectory/121104 "2024-12-04T11:39:32Z")

</div>

Hi everyone, In a current project I’m using Pkg.add(url="url/to/pkg", subdir = "in/this/subdir") . Now with 1.11 there is a \[sources\] section of the Project.toml file that makes this approach just a little bit nicer (e.…

---

## [How exactly is deepcopy defined?](https://discourse.julialang.org/t/how-exactly-is-deepcopy-defined/6445)

<div class="topic-metadata">

**Author:** [@Stephen\_Vavasis](https://discourse.julialang.org/u/Stephen_Vavasis)\
**Replies:** 12\
**Last updated:** [December 4, 2024, 10:58am UTC](https://discourse.julialang.org/t/how-exactly-is-deepcopy-defined/6445 "2024-12-04T10:58:47Z")

</div>

Observe the following: julia\> a = \[8,7,6\] 3-element Array{Int64,1}: 8 7 6 julia\> b = \[a,a\] 2-element Array{Array{Int64,1},1}: \[8, 7, 6\] \[8, 7, 6\] julia\> c=deepcopy(b) 2-element Array{Array{Int64,1},1}: \[8, 7, 6\] …

---

## [\[ANN\] DensityRatioEstimation.jl](https://discourse.julialang.org/t/ann-densityratioestimation-jl/82982)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 3\
**Last updated:** [December 4, 2024, 10:26am UTC](https://discourse.julialang.org/t/ann-densityratioestimation-jl/82982 "2024-12-04T10:26:00Z")

</div>

DensityRatioEstimation.jl is a Julia package for efficient estimation of ratios of density functions. These ratios are useful in a wide set of applications including two-sample tests, outlier detection, distribution comp…

---

## [Advent of Code 2024](https://discourse.julialang.org/t/advent-of-code-2024/123444)

<div class="topic-metadata">

**Author:** [@Qfl3x](https://discourse.julialang.org/u/Qfl3x)\
**Replies:** 1\
**Last updated:** [December 4, 2024, 10:24am UTC](https://discourse.julialang.org/t/advent-of-code-2024/123444 "2024-12-04T10:24:35Z")

</div>

Is any one else participating in AoC2024? Perhaps we could share different solutions? (Maybe different threads for each day if enough people are interested)

---

## [Does stdlib network sockets use only first thread?](https://discourse.julialang.org/t/does-stdlib-network-sockets-use-only-first-thread/123027)

<div class="topic-metadata">

**Author:** [@Pedro](https://discourse.julialang.org/u/Pedro)\
**Replies:** 6\
**Last updated:** [December 4, 2024, 10:16am UTC](https://discourse.julialang.org/t/does-stdlib-network-sockets-use-only-first-thread/123027 "2024-12-04T10:16:17Z")

</div>

I am writing a multi-threaded applications with a GUI (CImGui.jl) and a network sockets (Base.Sockets) to handle low-latency data stream over local network via UDP. I have a few independent threads to handle data proces…

---

## [How (best) to transform a huge DataFrame into wide-format](https://discourse.julialang.org/t/how-best-to-transform-a-huge-dataframe-into-wide-format/123415)

<div class="topic-metadata">

**Author:** [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Replies:** 8\
**Last updated:** [December 4, 2024, 10:14am UTC](https://discourse.julialang.org/t/how-best-to-transform-a-huge-dataframe-into-wide-format/123415 "2024-12-04T10:14:13Z")

</div>

I have a DataFrame with columns like open, high, low, close, and vol for multiple tickers, e.g. df1 = DataFrame( date\_time = repeat(\["2024-12-02T14:30:00", "2024-12-02T16:00:00","2024-12-02T17:30:00", "2024-12-02T19:00:…

---

## [Extend julia module](https://discourse.julialang.org/t/extend-julia-module/123407)

<div class="topic-metadata">

**Author:** [@Sergey](https://discourse.julialang.org/u/Sergey)\
**Replies:** 7\
**Last updated:** [December 4, 2024, 10:02am UTC](https://discourse.julialang.org/t/extend-julia-module/123407 "2024-12-04T10:02:25Z")

</div>

Hi. I try to understand modules in julia. And cant figure out how to extend julia module. Suppose i have a module: module Test t :: Float64 = 0 end how to add new function or variable to the module from another …

---

## [Evaluate MvNormal pdf on gpu array](https://discourse.julialang.org/t/evaluate-mvnormal-pdf-on-gpu-array/123443)

<div class="topic-metadata">

**Author:** [@jar1](https://discourse.julialang.org/u/jar1)\
**Replies:** 0\
**Last updated:** [December 4, 2024, 9:45am UTC](https://discourse.julialang.org/t/evaluate-mvnormal-pdf-on-gpu-array/123443 "2024-12-04T09:45:04Z")

</div>

Is there a way to evaluate MvNormal densities on GPU data? using Distributions, CUDA julia\> logpdf(MvNormal((rand(2)), (diagm(rand(2)))), rand(2)) -1.251537609209612 julia\> logpdf(MvNormal(cu(rand(2)), cu(diagm(rand(2…

---

## [Reading characters until the space key is pressed](https://discourse.julialang.org/t/reading-characters-until-the-space-key-is-pressed/123408)

<div class="topic-metadata">

**Author:** [@hack3rcon](https://discourse.julialang.org/u/hack3rcon)\
**Replies:** 2\
**Last updated:** [December 4, 2024, 9:32am UTC](https://discourse.julialang.org/t/reading-characters-until-the-space-key-is-pressed/123408 "2024-12-04T09:32:56Z")

</div>

Hello, I want to write a program that receives data from the input and terminates the program as soon as the space key is pressed. I wrote the following program: function space() print("Please write something: ") …

---

## [Differential Equation Log Plot](https://discourse.julialang.org/t/differential-equation-log-plot/123435)

<div class="topic-metadata">

**Author:** [@TheLazyFarmer](https://discourse.julialang.org/u/TheLazyFarmer)\
**Replies:** 1\
**Last updated:** [December 4, 2024, 8:21am UTC](https://discourse.julialang.org/t/differential-equation-log-plot/123435 "2024-12-04T08:21:21Z")

</div>

Hello, I have some values from a differential equation I solved, I am trying to plot the y-axis as a logarithmic. However, I am unsure how to go about this approach: For reference, I have this example solution from an …

---

## [Addprocs\_slurm not connecting to all available workers](https://discourse.julialang.org/t/addprocs-slurm-not-connecting-to-all-available-workers/123149)

<div class="topic-metadata">

**Author:** [@jewh](https://discourse.julialang.org/u/jewh)\
**Replies:** 7\
**Last updated:** [December 4, 2024, 7:17am UTC](https://discourse.julialang.org/t/addprocs-slurm-not-connecting-to-all-available-workers/123149 "2024-12-04T07:17:47Z")

</div>

I’m using Distributed and ClusterManagers to run large numbers of simulations in parallel on my university HPC cluster. Scheduling and job management on the cluster is handled by Slurm. I initialise each of the parallel…

---

## [How can you get the Lagrange/KKT multipliers out of JuMP when using Ipopt?](https://discourse.julialang.org/t/how-can-you-get-the-lagrange-kkt-multipliers-out-of-jump-when-using-ipopt/123432)

<div class="topic-metadata">

**Author:** [@lamont](https://discourse.julialang.org/u/lamont)\
**Replies:** 3\
**Last updated:** [December 4, 2024, 3:46am UTC](https://discourse.julialang.org/t/how-can-you-get-the-lagrange-kkt-multipliers-out-of-jump-when-using-ipopt/123432 "2024-12-04T03:46:46Z")

</div>

CasADI has lam\_x and lam\_g outputs. I can’t find in what they’re calling in Ipopt to get these, or I’d try digging into the Ipopt.jl code to see where it was. I haven’t had any luck with the jump-dev or ipopt documenta…

---

## ["Int64" error message during Optimisation](https://discourse.julialang.org/t/int64-error-message-during-optimisation/123382)

<div class="topic-metadata">

**Author:** [@Jordie](https://discourse.julialang.org/u/Jordie)\
**Replies:** 5\
**Last updated:** [December 4, 2024, 1:19am UTC](https://discourse.julialang.org/t/int64-error-message-during-optimisation/123382 "2024-12-04T01:19:30Z")

</div>

Hi, I am trying to find multiple parameters for the optimized system which is governed by a system of equations. In my code, I need to be able to use 4 or 5 equations and determine the parameters for the optimized syste…

---

## [How to make WGLMakie play nice with the vscode's plot pane](https://discourse.julialang.org/t/how-to-make-wglmakie-play-nice-with-the-vscodes-plot-pane/123424)

<div class="topic-metadata">

**Author:** [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)\
**Replies:** 2\
**Last updated:** [December 3, 2024, 10:39pm UTC](https://discourse.julialang.org/t/how-to-make-wglmakie-play-nice-with-the-vscodes-plot-pane/123424 "2024-12-03T22:39:47Z")

</div>

With CairoMakie or GLMakie, we can switch between different plots with left/right arrow, but when the backend is set to WGLMakie, this function seems broken? Usage example could be that, especially with 3d plots, rotati…

[Previous page](https://discourse.julialang.org/latest.md?page=260)

[Next page](https://discourse.julialang.org/latest.md?page=262)