# \#question

**URL:** https://discourse.julialang.org/tag/question/3.md

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

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## [How to return a macro from a macro?](https://discourse.julialang.org/t/how-to-return-a-macro-from-a-macro/139612)

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**Author:** [@ysaak](https://discourse.julialang.org/u/ysaak)\
**Replies:** 7\
**Last updated:** [September 23, 2026, 3:35pm UTC](https://discourse.julialang.org/t/how-to-return-a-macro-from-a-macro/139612 "2026-09-23T15:35:31Z")

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I want to create a macro that receives the header foo(args) and body begin ... end and returns a macro version of it. macro macwo(header::Expr, body::Expr) #= macro header body end =# end # Impl…

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## [Cannot download general registry due to a corporate antivirus](https://discourse.julialang.org/t/cannot-download-general-registry-due-to-a-corporate-antivirus/139605)

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**Author:** [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Replies:** 8\
**Last updated:** [September 23, 2026, 2:02pm UTC](https://discourse.julialang.org/t/cannot-download-general-registry-due-to-a-corporate-antivirus/139605 "2026-09-23T14:02:46Z")

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A change in my corporate antivirus cause problem when I try to install new packages. I tried to change JULIA\_PKG\_DOWNLOAD\_TIMEOUT and Curl.CURLOPT\_LOW\_SPEED limits but it seems to have no effect: julia\> ENV\["JULIA\_PKG\_…

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## [Understanding jump model preparation cost](https://discourse.julialang.org/t/understanding-jump-model-preparation-cost/138472)

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**Author:** [@lmshk](https://discourse.julialang.org/u/lmshk)\
**Replies:** 19\
**Last updated:** [September 23, 2026, 1:32pm UTC](https://discourse.julialang.org/t/understanding-jump-model-preparation-cost/138472 "2026-09-23T13:32:43Z")

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I am using Catalyst.jl to make JumpProblems of around 160k species and a fairly sparse interaction structure that includes what JumpProcesses.jl calls “constant-rate jump” (CRJ) reactions. This works, but JumpProblem con…

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## [Agent protocols beyond MCP in Julia?](https://discourse.julialang.org/t/agent-protocols-beyond-mcp-in-julia/139563)

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**Author:** [@scelles](https://discourse.julialang.org/u/scelles)\
**Replies:** 6\
**Last updated:** [September 22, 2026, 2:04pm UTC](https://discourse.julialang.org/t/agent-protocols-beyond-mcp-in-julia/139563 "2026-09-22T14:04:51Z")

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Hello, I’ve been looking at some of the emerging agent protocols beyond MCP: AG-UI, A2UI, Agent Client Protocol (ACP), Agent Control Protocol (also ACP), and Agent2Agent (A2A). I haven’t seen much discussion about them…

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## [Change z order/index in Plots.jl](https://discourse.julialang.org/t/change-z-order-index-in-plots-jl/47250)

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**Author:** [@OvidiusCicero](https://discourse.julialang.org/u/OvidiusCicero)\
**Replies:** 12\
**Last updated:** [September 21, 2026, 9:50am UTC](https://discourse.julialang.org/t/change-z-order-index-in-plots-jl/47250 "2026-09-21T09:50:37Z")

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Is there a way to change the order in which plots are drawn in Plots.jl? (z index or z order in other suites) For example plot(rand(5)) // unfilled plot!(2rand(5); fill=0) // filled I would like to show unfi…

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## [Find area and perimeters of labeled segments for binary image](https://discourse.julialang.org/t/find-area-and-perimeters-of-labeled-segments-for-binary-image/124552)

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**Author:** [@Alex\_Milns](https://discourse.julialang.org/u/Alex_Milns)\
**Replies:** 3\
**Last updated:** [September 19, 2026, 2:11am UTC](https://discourse.julialang.org/t/find-area-and-perimeters-of-labeled-segments-for-binary-image/124552 "2026-09-19T02:11:29Z")

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Hi! I try to calculate area and perimeters of labeled regions of binary image. For example: using Images, ImageView, ImageSegmentation, TestImages, IndirectArrays, ImageMorphology img = testimage("blobs") # f = Adaptive…

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## [Write CSV row by row](https://discourse.julialang.org/t/write-csv-row-by-row/138171)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 8\
**Last updated:** [September 17, 2026, 6:15pm UTC](https://discourse.julialang.org/t/write-csv-row-by-row/138171 "2026-09-17T18:15:14Z")

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I have a computation that calculates rows of data, let’s say they are NamedTuples with the same keys. I would like to emit this into a CSV file without collecting or making it an iterable. ▶ Why? Pseudocode for what I wa…

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## [New syntax for function decoration with macros](https://discourse.julialang.org/t/new-syntax-for-function-decoration-with-macros/139512)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 2\
**Last updated:** [September 17, 2026, 10:40am UTC](https://discourse.julialang.org/t/new-syntax-for-function-decoration-with-macros/139512 "2026-09-17T10:40:31Z")

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I have noticed, that the Base functions now use a new syntax, where the decorator macros such as @inline or @propagate\_inbounds appear as the first line of the body of the function. What version of Julia was this synta…

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## [Interactive development in Julia compared to \[Common\] Lisp?](https://discourse.julialang.org/t/interactive-development-in-julia-compared-to-common-lisp/139494)

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**Author:** [@farooqkz](https://discourse.julialang.org/u/farooqkz)\
**Replies:** 10\
**Last updated:** [September 17, 2026, 6:58am UTC](https://discourse.julialang.org/t/interactive-development-in-julia-compared-to-common-lisp/139494 "2026-09-17T06:58:03Z")

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Hello Hello. I am looking for a programming language for some R&D work in the field of Evolutionary Computation and AI. Interactive development in Common Lisp comes very handy when you are designing algorithms or exper…

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## [JuliaCon 2026 Proceedings - Submission question](https://discourse.julialang.org/t/juliacon-2026-proceedings-submission-question/139492)

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**Author:** [@StackEnjoyer](https://discourse.julialang.org/u/StackEnjoyer)\
**Replies:** 1\
**Last updated:** [September 17, 2026, 12:57am UTC](https://discourse.julialang.org/t/juliacon-2026-proceedings-submission-question/139492 "2026-09-17T00:57:16Z")

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Dear JuliaCon team, I gave a talk at this years Juliacon ( Modeling optical setups with BeamletOptics.jl :: JuliaCon 2026 :: pretalx) and wanted to submit a paper to the proceedings. Upon submission via the form linked…

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## [AiresDB: We built a database engine in Julia for our university capstone project](https://discourse.julialang.org/t/airesdb-we-built-a-database-engine-in-julia-for-our-university-capstone-project/139476)

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**Author:** [@aires-id](https://discourse.julialang.org/u/aires-id)\
**Replies:** 4\
**Last updated:** [September 16, 2026, 1:46pm UTC](https://discourse.julialang.org/t/airesdb-we-built-a-database-engine-in-julia-for-our-university-capstone-project/139476 "2026-09-16T13:46:58Z")

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Hi everyone! We are three Oil & Gas Engineering students from Institut Teknologi Sumatera (ITERA), Indonesia, and for our university capstone project we decided to do something slightly unusual: build a database engine…

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## [Play video and sound](https://discourse.julialang.org/t/play-video-and-sound/6498)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 9\
**Last updated:** [September 15, 2026, 8:23pm UTC](https://discourse.julialang.org/t/play-video-and-sound/6498 "2026-09-15T20:23:33Z")

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Is there a way we can play a video and its sound currently in Julia? The excellent VideoIO.jl package doesn’t play sound.

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## [In my JuMP model, the LP file preserves the original variable names, but the MPS file appears to rename them, so how can I map the Gurobi .sol solution back to the original JuMP variables?](https://discourse.julialang.org/t/in-my-jump-model-the-lp-file-preserves-the-original-variable-names-but-the-mps-file-appears-to-rename-them-so-how-can-i-map-the-gurobi-sol-solution-back-to-the-original-jump-variables/139462)

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**Author:** [@amit\_97](https://discourse.julialang.org/u/amit_97)\
**Replies:** 2\
**Last updated:** [September 14, 2026, 10:19pm UTC](https://discourse.julialang.org/t/in-my-jump-model-the-lp-file-preserves-the-original-variable-names-but-the-mps-file-appears-to-rename-them-so-how-can-i-map-the-gurobi-sol-solution-back-to-the-original-jump-variables/139462 "2026-09-14T22:19:23Z")

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Hi everyone, I’m generating both .lp and .mps files from the same JuMP model using Gurobi. In the LP file, the original JuMP variable names are preserved, for example: 1200 x2\[1,(1,\_0)\] - 41054.62117964038 B2\[1,(1,\_0)…

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## [School Research: Habits and Preferences of Julia Developers](https://discourse.julialang.org/t/school-research-habits-and-preferences-of-julia-developers/139204)

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**Author:** [@RenoDolman](https://discourse.julialang.org/u/RenoDolman)\
**Replies:** 4\
**Last updated:** [September 14, 2026, 8:32am UTC](https://discourse.julialang.org/t/school-research-habits-and-preferences-of-julia-developers/139204 "2026-09-14T08:32:00Z")

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Hi everyone! Currently I’m conducting a small scale research into the habits and preferences of developers that use the Julia language. Specifically: What online platform you go to for troubleshooting while coding in…

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## [Building a system image using Julia 1.13 fails on Windows](https://discourse.julialang.org/t/building-a-system-image-using-julia-1-13-fails-on-windows/139436)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 0\
**Last updated:** [September 13, 2026, 9:18am UTC](https://discourse.julialang.org/t/building-a-system-image-using-julia-1-13-fails-on-windows/139436 "2026-09-13T09:18:24Z")

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Building a system image on Windows 10 fails if I use Julia 1.13, it succeeds using Julia 1.12. On Julia 1.12 it needs about 34 GB RAM (RAM+pagefile) and 30 minutes. On Julia 1.13 it fails even with 54 GB RAM after 1h:2…

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## [Mixing time-discrete and time-continuous systems in a simulation](https://discourse.julialang.org/t/mixing-time-discrete-and-time-continuous-systems-in-a-simulation/74277)

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**Author:** [@tqml](https://discourse.julialang.org/u/tqml)\
**Replies:** 22\
**Last updated:** [September 11, 2026, 5:23pm UTC](https://discourse.julialang.org/t/mixing-time-discrete-and-time-continuous-systems-in-a-simulation/74277 "2026-09-11T17:23:15Z")

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Hello all! Does anyone what’s currently the best way in the Julia ecosystem to mix time-continuous and time-discrete systems in one simulation? (e.g. I want to simulate a continuous system regulated by time-discrete con…

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## ["Fixed iteration" DiffEq solvers on the GPU?](https://discourse.julialang.org/t/fixed-iteration-diffeq-solvers-on-the-gpu/139357)

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**Author:** [@jl\_enthusiast](https://discourse.julialang.org/u/jl_enthusiast)\
**Replies:** 2\
**Last updated:** [September 11, 2026, 2:37pm UTC](https://discourse.julialang.org/t/fixed-iteration-diffeq-solvers-on-the-gpu/139357 "2026-09-11T14:37:32Z")

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Hey, I am currently trying to (re)write some old hobby project into Julia (related to raytracing) and want to rely on the DiffEq solver interface, ideally inside a KernelAbstractions.jl kernel (as I am performing a lot …

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## [Pvlib for Julia?](https://discourse.julialang.org/t/pvlib-for-julia/118952)

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**Author:** [@langestefan](https://discourse.julialang.org/u/langestefan)\
**Replies:** 19\
**Last updated:** [September 10, 2026, 2:47pm UTC](https://discourse.julialang.org/t/pvlib-for-julia/118952 "2026-09-10T14:47:10Z")

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Hi, I have been happily using Julia for a year or so now after being a python user for many more years. The only thing I am really missing is a substitute for pvlib. pvlib is a popular toolbox for photovoltaic systems …

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## [Best Practices for Using Coding Agents with Julia?](https://discourse.julialang.org/t/best-practices-for-using-coding-agents-with-julia/136829)

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**Author:** [@Matt\_jl](https://discourse.julialang.org/u/Matt_jl)\
**Replies:** 55\
**Last updated:** [September 10, 2026, 2:07am UTC](https://discourse.julialang.org/t/best-practices-for-using-coding-agents-with-julia/136829 "2026-09-10T02:07:03Z")

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Very easy, just like the title says: What are the best practices for letting coding agents start and manage Julia sessions for testing and debugging, while keeping the workflow safe, reproducible, and easy to reason abo…

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## [Makie how to conditionaly hide a legend entry in \`axislegend\`](https://discourse.julialang.org/t/makie-how-to-conditionaly-hide-a-legend-entry-in-axislegend/139312)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 2\
**Last updated:** [September 9, 2026, 3:24pm UTC](https://discourse.julialang.org/t/makie-how-to-conditionaly-hide-a-legend-entry-in-axislegend/139312 "2026-09-09T15:24:00Z")

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I have a function that makes the plot on the left: it achieve this via the standard scatter!(xxx; label = "something") infrastructure, after which I call axislegend. I want to use the same plot on the right. On top …

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## [ModelingToolkit: Internal error in runtime](https://discourse.julialang.org/t/modelingtoolkit-internal-error-in-runtime/139291)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 2\
**Last updated:** [September 9, 2026, 9:39am UTC](https://discourse.julialang.org/t/modelingtoolkit-internal-error-in-runtime/139291 "2026-09-09T09:39:43Z")

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When creating a system image of Tethers.jl on Windows, I got this error: Precompiling packages finished. 503 dependencies successfully precompiled in 342 seconds. 26 already precompiled. 23 dependencies precompiled …

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## [Simulink alternative in Julia for control engineering](https://discourse.julialang.org/t/simulink-alternative-in-julia-for-control-engineering/131961)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 32\
**Last updated:** [September 8, 2026, 7:05pm UTC](https://discourse.julialang.org/t/simulink-alternative-in-julia-for-control-engineering/131961 "2026-09-08T19:05:27Z")

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In my group, many use Matlab and Simulink for control engineering. It is very easy for them since this his how you learn control engineering, by block diagrams. Regardless of the user interface, what options would I have…

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## [Invalidations caused by FixedPointNumbers](https://discourse.julialang.org/t/invalidations-caused-by-fixedpointnumbers/139232)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [September 6, 2026, 10:21pm UTC](https://discourse.julialang.org/t/invalidations-caused-by-fixedpointnumbers/139232 "2026-09-06T22:21:48Z")

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The FixedPointNumbers package is causing many invalidations, even though it does not engage in type piracy. For details, see: Loading FixedPointNumbers invalidates ~7,700 precompiled method instances (7x slower first mtk…

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## [API design help: Wrapping ITensorMPS structs and extending it to my package](https://discourse.julialang.org/t/api-design-help-wrapping-itensormps-structs-and-extending-it-to-my-package/139164)

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**Author:** [@Gautameshwar](https://discourse.julialang.org/u/Gautameshwar)\
**Replies:** 2\
**Last updated:** [September 4, 2026, 2:36am UTC](https://discourse.julialang.org/t/api-design-help-wrapping-itensormps-structs-and-extending-it-to-my-package/139164 "2026-09-04T02:36:12Z")

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Hi Julia community! I am currently developing a package, ProcessTensors.jl, that uses an MPS/MPO architecture to construct process tensors and simulate non-Markovian quantum dynamics. I built this package on top of the …

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## [NUTS algorithm in Turing.jl](https://discourse.julialang.org/t/nuts-algorithm-in-turing-jl/135592)

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**Author:** [@Sahil\_Khan](https://discourse.julialang.org/u/Sahil_Khan)\
**Replies:** 7\
**Last updated:** [September 2, 2026, 3:52am UTC](https://discourse.julialang.org/t/nuts-algorithm-in-turing-jl/135592 "2026-09-02T03:52:43Z")

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Dear all, Can someone explain to me that the n\_adapts in case NUTS algorithm NUTS(n\_adapts, δ) used in Turing sample function is number of iteration or number of accepted samples before main sampling? Because when I giv…

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## [HDF5.jl variable length string](https://discourse.julialang.org/t/hdf5-jl-variable-length-string/98808)

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**Author:** [@thomaskroi1996](https://discourse.julialang.org/u/thomaskroi1996)\
**Replies:** 10\
**Last updated:** [April 4, 2024, 10:38pm UTC](https://discourse.julialang.org/t/hdf5-jl-variable-length-string/98808 "2024-04-04T22:38:46Z")

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Hello everyone! I am currently trying to translate i python code to julia! What i am trying to do, broken down, is creating a dataset where dtype=“String”. I know that to do that in python you have to declare a special …

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## [With DynamicPolynomials and non-commutative variables, (x+y)\*z does not work](https://discourse.julialang.org/t/with-dynamicpolynomials-and-non-commutative-variables-x-y-z-does-not-work/139046)

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**Author:** [@The\_Suffocated](https://discourse.julialang.org/u/The_Suffocated)\
**Replies:** 4\
**Last updated:** [August 30, 2026, 3:51pm UTC](https://discourse.julialang.org/t/with-dynamicpolynomials-and-non-commutative-variables-x-y-z-does-not-work/139046 "2026-08-30T15:51:52Z")

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How to right-multiply x+y by z in DynamicPolynomials when x, y, z are non-commutative? I have tried (x+y)\*z, but Julia returns an ERROR: MethodError: no method matching map\_exponents(::typeof(+), ::MonomialVector{…}, ::V…

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## [Merging and formatting cells in Excel from Julia](https://discourse.julialang.org/t/merging-and-formatting-cells-in-excel-from-julia/18786)

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**Author:** [@ahmetumutdurmus](https://discourse.julialang.org/u/ahmetumutdurmus)\
**Replies:** 3\
**Last updated:** [August 30, 2026, 2:55pm UTC](https://discourse.julialang.org/t/merging-and-formatting-cells-in-excel-from-julia/18786 "2026-08-30T14:55:30Z")

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Hello, Is there a way of merging cells, formatting and aligning cell contents in an Excel file using Julia? Using a package is also fine. I am currently using XLSX.jl to write to Excel files yet for merging, formatting …

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## [Write to XLSX file while maintaining formatting](https://discourse.julialang.org/t/write-to-xlsx-file-while-maintaining-formatting/87715)

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**Author:** [@Carl\_Talsma](https://discourse.julialang.org/u/Carl_Talsma)\
**Replies:** 2\
**Last updated:** [August 30, 2026, 2:54pm UTC](https://discourse.julialang.org/t/write-to-xlsx-file-while-maintaining-formatting/87715 "2026-08-30T14:54:34Z")

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Hi, I’m trying to write data to a .xlsx file that has already been formatted (cell size, colors, etc.). Is there anyway to write data to a .xlsx file while maintaining the existing formatting? I’m currently using the XL…

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## [XLSX cell format](https://discourse.julialang.org/t/xlsx-cell-format/113975)

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**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 8\
**Last updated:** [August 30, 2026, 8:11am UTC](https://discourse.julialang.org/t/xlsx-cell-format/113975 "2026-08-30T08:11:49Z")

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I tried different approaches to specify a numerical format with 4 decimal places of all the cells in an Excel sheet generated using XLSX.jl. None of them worked. Any suggestions?

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