# Latest

**URL:** https://discourse.julialang.org/latest.md?page=493

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

**Page:** 494

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## [Automating the Best Layout for Plotting Variables?](https://discourse.julialang.org/t/automating-the-best-layout-for-plotting-variables/109672)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 3\
**Last updated:** [February 4, 2024, 2:57pm UTC](https://discourse.julialang.org/t/automating-the-best-layout-for-plotting-variables/109672 "2024-02-04T14:57:37Z")

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Hi folks! I have been struggling with a problem on how to best plot variables that are not always guaranteed in data. Let me show an example of what I am talking about: Suppose I have a dataframe that looks something l…

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## [Oceananigans.jl](https://discourse.julialang.org/t/oceananigans-jl/109693)

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**Author:** [@benslinux](https://discourse.julialang.org/u/benslinux)\
**Replies:** 0\
**Last updated:** [February 4, 2024, 8:33am UTC](https://discourse.julialang.org/t/oceananigans-jl/109693 "2024-02-04T08:33:58Z")

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\*\* SOLVED - Tried running the demo program for Oceananigans - I got as far as this: julia\> run!(simulation) \[ Info: Initializing simulation… \[ Info: … simulation initialization complete (88.034 ms) \[ Info: Execu…

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## [How can I read a GDAL dataset from an io stream?](https://discourse.julialang.org/t/how-can-i-read-a-gdal-dataset-from-an-io-stream/109679)

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**Author:** [@maxfreu](https://discourse.julialang.org/u/maxfreu)\
**Replies:** 2\
**Last updated:** [February 4, 2024, 12:14pm UTC](https://discourse.julialang.org/t/how-can-i-read-a-gdal-dataset-from-an-io-stream/109679 "2024-02-04T12:14:37Z")

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Hi! I’m wondering how I can read a gdal dataset that comes in the form of some io stream. Imagine you iterate over a tar file of tifs via TarIterator. For each tif there is an io stream containing the raw dataset data as…

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## [Two point boundary value problem solution not obeying boundary condition](https://discourse.julialang.org/t/two-point-boundary-value-problem-solution-not-obeying-boundary-condition/109633)

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**Author:** [@bast](https://discourse.julialang.org/u/bast)\
**Replies:** 1\
**Last updated:** [February 4, 2024, 10:47am UTC](https://discourse.julialang.org/t/two-point-boundary-value-problem-solution-not-obeying-boundary-condition/109633 "2024-02-04T10:47:36Z")

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Hello, I am trying to replicate the solution of an optimal control problem (Redirecting). The canonical system is given by \\begin{aligned} & \\dot{x}(t)=x(t)\\left(1-\\frac{x(t)}{a}\\right)-\\frac{1}{(c+\\tau)} \\frac{x(t)^…

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## [Memoization in mcmc](https://discourse.julialang.org/t/memoization-in-mcmc/109694)

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**Author:** [@swsw](https://discourse.julialang.org/u/swsw)\
**Replies:** 0\
**Last updated:** [February 4, 2024, 9:13am UTC](https://discourse.julialang.org/t/memoization-in-mcmc/109694 "2024-02-04T09:13:04Z")

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Hi there, I wondered if how Turing or RxInfer deals w/ the following situation. For example, I have 10 parameters x1,…x10, the likelihood function is as follows. x1^2 + … + x10^2 Apparently, when updating x1, the o…

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## [Allocations in broadcasted assignment (StackOverflow question)](https://discourse.julialang.org/t/allocations-in-broadcasted-assignment-stackoverflow-question/109680)

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**Author:** [@bert](https://discourse.julialang.org/u/bert)\
**Replies:** 2\
**Last updated:** [February 4, 2024, 7:21am UTC](https://discourse.julialang.org/t/allocations-in-broadcasted-assignment-stackoverflow-question/109680 "2024-02-04T07:21:49Z")

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I came across this StackOverflow post and am wondering what the solution is. I have played around with the example in this post (copied below) and, like the author, cannot get rid of the allocation in d’s broadcast assig…

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## [Are database connection pools typically used with concurrency](https://discourse.julialang.org/t/are-database-connection-pools-typically-used-with-concurrency/109689)

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**Author:** [@rdavis120](https://discourse.julialang.org/u/rdavis120)\
**Replies:** 2\
**Last updated:** [February 4, 2024, 3:44am UTC](https://discourse.julialang.org/t/are-database-connection-pools-typically-used-with-concurrency/109689 "2024-02-04T03:44:10Z")

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When creating hundreds of tasks using @spawn (with multiple threads), where each task has a connection to an embedded database, is it necessary to use a connection pool structure or can each task maintain its own DBInter…

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## [Packages on GitHub that I can never download](https://discourse.julialang.org/t/packages-on-github-that-i-can-never-download/109501)

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**Author:** [@jackmarry](https://discourse.julialang.org/u/jackmarry)\
**Replies:** 16\
**Last updated:** [February 4, 2024, 3:11am UTC](https://discourse.julialang.org/t/packages-on-github-that-i-can-never-download/109501 "2024-02-04T03:11:38Z")

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julia newbie, there are some packages on GitHub that I can never download, some code packages are unregistered, can I install them by downloading the source code files from GitHub, or use them locally.

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## [How to create a new axis in a loop using CairoMakie?](https://discourse.julialang.org/t/how-to-create-a-new-axis-in-a-loop-using-cairomakie/109623)

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**Author:** [@albrightand](https://discourse.julialang.org/u/albrightand)\
**Replies:** 4\
**Last updated:** [February 4, 2024, 2:59am UTC](https://discourse.julialang.org/t/how-to-create-a-new-axis-in-a-loop-using-cairomakie/109623 "2024-02-04T02:59:37Z")

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I’m trying to create a series of histograms by looping through a data frame and plotting each entry as a histogram. There is 20 different plots, so it would be inconvenient to not use a loop. In the Makie docs, it shows…

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## [At present, in what aspects is Julia still relatively weak compared to other mainstream programming languages?](https://discourse.julialang.org/t/at-present-in-what-aspects-is-julia-still-relatively-weak-compared-to-other-mainstream-programming-languages/109583)

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**Author:** [@WuSiren](https://discourse.julialang.org/u/WuSiren)\
**Replies:** 63\
**Last updated:** [February 4, 2024, 1:24am UTC](https://discourse.julialang.org/t/at-present-in-what-aspects-is-julia-still-relatively-weak-compared-to-other-mainstream-programming-languages/109583 "2024-02-04T01:24:22Z")

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At present, in what aspects is Julia still relatively weak compared to other mainstream programming languages? Or to put it another way, what aspects should Julia strengthen in the future? --A Julian with a surge of love…

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## [Why does a non-allocating function seem to allocate when being called in a multi-threaded map?](https://discourse.julialang.org/t/why-does-a-non-allocating-function-seem-to-allocate-when-being-called-in-a-multi-threaded-map/79531)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 3\
**Last updated:** [February 3, 2024, 10:52pm UTC](https://discourse.julialang.org/t/why-does-a-non-allocating-function-seem-to-allocate-when-being-called-in-a-multi-threaded-map/79531 "2024-02-03T22:52:32Z")

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I am measuring allocations using TimerOutputs. Here is a MWE: julia\> Threads.nthreads() 2 julia\> using TimerOutputs, Folds julia\> f!(M) = begin t = TimerOutput() @timeit t "update" M .= 1; println…

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## [How to implement a filtered derivative](https://discourse.julialang.org/t/how-to-implement-a-filtered-derivative/109441)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 29\
**Last updated:** [February 3, 2024, 10:51pm UTC](https://discourse.julialang.org/t/how-to-implement-a-filtered-derivative/109441 "2024-02-03T22:51:18Z")

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How can I implement a filtered, discrete time derivative following the equations: u\_1 = u − y\_1 dy\_1/dt = (1 / T\_D) \* u\_1 y = (K\_D / T\_D) \* u\_1 filtertau = 0.01 as described on page 128 of the following document: http…

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## [Is PyJulia org, e.g. juliacall (or pyjulia) Python packages maintained?](https://discourse.julialang.org/t/is-pyjulia-org-e-g-juliacall-or-pyjulia-python-packages-maintained/109277)

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**Author:** [@bdas123](https://discourse.julialang.org/u/bdas123)\
**Replies:** 36\
**Last updated:** [February 3, 2024, 10:01pm UTC](https://discourse.julialang.org/t/is-pyjulia-org-e-g-juliacall-or-pyjulia-python-packages-maintained/109277 "2024-02-03T22:01:48Z")

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Hello, I’m just checking if PyJulia is maintained or if there is a better way to call a Julia script from a Python code.

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## [Determine whether an element is in an array](https://discourse.julialang.org/t/determine-whether-an-element-is-in-an-array/109659)

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**Author:** [@jisutich](https://discourse.julialang.org/u/jisutich)\
**Replies:** 4\
**Last updated:** [February 3, 2024, 5:23pm UTC](https://discourse.julialang.org/t/determine-whether-an-element-is-in-an-array/109659 "2024-02-03T17:23:11Z")

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Hi I am thinking how to achieve similar thing to numpy’s where function in Julia. Suppose I have an array A and now I want to determine if there is any element of A belong to the regime \[a-1e-12,a+1e-12\]. If yes I want …

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## [How to get mouse coords in Mousetrap.jl](https://discourse.julialang.org/t/how-to-get-mouse-coords-in-mousetrap-jl/109685)

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**Author:** [@Lilith](https://discourse.julialang.org/u/Lilith)\
**Replies:** 0\
**Last updated:** [February 3, 2024, 9:21pm UTC](https://discourse.julialang.org/t/how-to-get-mouse-coords-in-mousetrap-jl/109685 "2024-02-03T21:21:31Z")

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Is there a function to poll the current mouse position in Mousetrap.jl? I want my render\_area to render differently depending on where the mouse is.

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## [Memory build-up when loading DataFrames in a loop](https://discourse.julialang.org/t/memory-build-up-when-loading-dataframes-in-a-loop/109678)

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**Author:** [@isaacjeffersonlee](https://discourse.julialang.org/u/isaacjeffersonlee)\
**Replies:** 2\
**Last updated:** [February 3, 2024, 6:24pm UTC](https://discourse.julialang.org/t/memory-build-up-when-loading-dataframes-in-a-loop/109678 "2024-02-03T18:24:02Z")

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When I sequentially load a very large DataFrame into memory and then sort it in place, the memory usage builds eventually running out of memory? Is there anything I can do to prevent this? Why is the garbage collector n…

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## [Define Python function in Julia file... with package imports](https://discourse.julialang.org/t/define-python-function-in-julia-file-with-package-imports/109663)

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**Author:** [@gdalle](https://discourse.julialang.org/u/gdalle)\
**Replies:** 2\
**Last updated:** [February 3, 2024, 5:52pm UTC](https://discourse.julialang.org/t/define-python-function-in-julia-file-with-package-imports/109663 "2024-02-03T17:52:35Z")

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Thanks to PythonCall.jl, Python functions can be defined in Julia files like so: julia\> using PythonCall julia\> @pyexec """ def fib(n): a, b = 0, 1 for i in range(n): a, b = …

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## [3D surfaces + time slider](https://discourse.julialang.org/t/3d-surfaces-time-slider/109673)

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**Author:** [@sob](https://discourse.julialang.org/u/sob)\
**Replies:** 2\
**Last updated:** [February 3, 2024, 5:49pm UTC](https://discourse.julialang.org/t/3d-surfaces-time-slider/109673 "2024-02-03T17:49:45Z")

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Hi, PlotlyJS provides the following code to represent multiple surfaces at once (see multiple surfaces): julia\> using PlotlyJS julia\> function multiple\_surface() z1 = Vector\[\[8.83, 8.89, 8.81, 8.87, 8.9, 8.…

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## [Throw and error](https://discourse.julialang.org/t/throw-and-error/109666)

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**Author:** [@jiang\_ming\_zhang](https://discourse.julialang.org/u/jiang_ming_zhang)\
**Replies:** 1\
**Last updated:** [February 3, 2024, 12:22pm UTC](https://discourse.julialang.org/t/throw-and-error/109666 "2024-02-03T12:22:11Z")

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julia\> a = 3 3 julia\> b = 4 4 julia\> throw("a:$a is unequal b:$b") ERROR: "a:3 is unequal b:4" Stacktrace: \[1\] top-level scope @ REPL\[19\]:1 I am a bit confused here. Is the ‘ERROR’ here indicating that there is s…

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## [Symbolics.jl Finding Coefficients of Cross Terms Problem](https://discourse.julialang.org/t/symbolics-jl-finding-coefficients-of-cross-terms-problem/109649)

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**Author:** [@Umut\_Can\_Turhan](https://discourse.julialang.org/u/Umut_Can_Turhan)\
**Replies:** 1\
**Last updated:** [February 3, 2024, 5:44pm UTC](https://discourse.julialang.org/t/symbolics-jl-finding-coefficients-of-cross-terms-problem/109649 "2024-02-03T17:44:42Z")

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When I try to run the following code, the print function always returns the integer 0 (zero). However, you can easily see that the coefficient of the z\[1\] \* z\[2\] term equals -2. The Symbolics.jl module is robust for just…

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## [What's the JuliaWiki?](https://discourse.julialang.org/t/whats-the-juliawiki/109335)

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**Author:** [@cormullion](https://discourse.julialang.org/u/cormullion)\
**Replies:** 14\
**Last updated:** [February 3, 2024, 3:34pm UTC](https://discourse.julialang.org/t/whats-the-juliawiki/109335 "2024-02-03T15:34:54Z")

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My searches for Julia-related information are returning results featuring the JuliaWiki. www.juliawiki.com/wiki/ which says: Welcome to the definitive resource for the Julia programming language. Whether you are a ne…

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## [3D plot labels customization](https://discourse.julialang.org/t/3d-plot-labels-customization/109675)

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**Author:** [@Maucejo](https://discourse.julialang.org/u/Maucejo)\
**Replies:** 0\
**Last updated:** [February 3, 2024, 4:44pm UTC](https://discourse.julialang.org/t/3d-plot-labels-customization/109675 "2024-02-03T16:44:02Z")

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Hi all, I am using Makie.jl as my main plotting library. Maybe I missed something in the doc, but I don’t know if it is possible to customize the ticks and axis labels layout of Axis3 to get something like in the figure …

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## [Integration of functions over geometries](https://discourse.julialang.org/t/integration-of-functions-over-geometries/81994)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 30\
**Last updated:** [February 3, 2024, 4:07pm UTC](https://discourse.julialang.org/t/integration-of-functions-over-geometries/81994 "2024-02-03T16:07:20Z")

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Cross-posting from Zulip’s #meshes.jl channel… Does anyone know of a good reference for integration rules over different geometries? For example, to integrate a function f over a triangle, we can consider the surface i…

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## [Unreasonably fast FFT on CUDA](https://discourse.julialang.org/t/unreasonably-fast-fft-on-cuda/109398)

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**Author:** [@jabru](https://discourse.julialang.org/u/jabru)\
**Replies:** 8\
**Last updated:** [February 3, 2024, 3:56pm UTC](https://discourse.julialang.org/t/unreasonably-fast-fft-on-cuda/109398 "2024-02-03T15:56:01Z")

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Hey there, so I am currently working on an algorithm that will likely strongly depend on the FFT very significantly. Therefore I am considering to do the FFT in FFTW on Cuda to speed up the algorithm. It is a 3d FFT wit…

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## [How fill a poly object with a color gradient defined by the values inside it?](https://discourse.julialang.org/t/how-fill-a-poly-object-with-a-color-gradient-defined-by-the-values-inside-it/109667)

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**Author:** [@Midez](https://discourse.julialang.org/u/Midez)\
**Replies:** 0\
**Last updated:** [February 3, 2024, 12:31pm UTC](https://discourse.julialang.org/t/how-fill-a-poly-object-with-a-color-gradient-defined-by-the-values-inside-it/109667 "2024-02-03T12:31:47Z")

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Hello everyone, to better understand what I eagerly try to do I have attached you the data and code using DelimitedFiles, CairoMakie, Colors ol = readdlm("/Users/.../outline.txt"); vx = readdlm("/Users/.../x\_data.txt"…

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## [Help with this code (deallocation/pointers on sparse matrices)](https://discourse.julialang.org/t/help-with-this-code-deallocation-pointers-on-sparse-matrices/109574)

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**Author:** [@Enlil50](https://discourse.julialang.org/u/Enlil50)\
**Replies:** 31\
**Last updated:** [February 3, 2024, 9:32am UTC](https://discourse.julialang.org/t/help-with-this-code-deallocation-pointers-on-sparse-matrices/109574 "2024-02-03T09:32:46Z")

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This is a follow up of a recent thread I made Sparse matrices copy arrays, do not view them I sum up all the shared ideas, with 2 code examples. This is intended as a much clearer version and prosecution of that thread,…

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## [Documenter generates inconsistent plots](https://discourse.julialang.org/t/documenter-generates-inconsistent-plots/109610)

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**Author:** [@putianyi888](https://discourse.julialang.org/u/putianyi888)\
**Replies:** 6\
**Last updated:** [February 3, 2024, 8:45am UTC](https://discourse.julialang.org/t/documenter-generates-inconsistent-plots/109610 "2024-02-03T08:45:45Z")

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An auto-generated plot in my package documentation is inconsistent across irrelevent commits. The most recent build changed the image while the related commit is irrelevant. Both images are different from what I get loc…

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## [KeyError in PowerModels](https://discourse.julialang.org/t/keyerror-in-powermodels/109656)

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**Author:** [@Rasoul](https://discourse.julialang.org/u/Rasoul)\
**Replies:** 3\
**Last updated:** [February 3, 2024, 6:16am UTC](https://discourse.julialang.org/t/keyerror-in-powermodels/109656 "2024-02-03T06:16:20Z")

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Hi All, I developed PowerModels and PowerModelsAnnex, then ran my customized code in PowerModelsAnnex and encountered the following error. Could you please provide guidance on how to resolve this? Thanks in advance! "E…

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## [BatchIntegralFunction not appearing to work as intended](https://discourse.julialang.org/t/batchintegralfunction-not-appearing-to-work-as-intended/109513)

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**Author:** [@HSnowden](https://discourse.julialang.org/u/HSnowden)\
**Replies:** 2\
**Last updated:** [February 3, 2024, 4:05am UTC](https://discourse.julialang.org/t/batchintegralfunction-not-appearing-to-work-as-intended/109513 "2024-02-03T04:05:09Z")

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I am trying to implement a batch integral function using the new BatchIntegralFunction rather than then deprecated nout/batch keywords. However, when I do, the in-place vector to fill place the answer in is the incorrec…

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## [Adding "calls for contributors" to the newsletter](https://discourse.julialang.org/t/adding-calls-for-contributors-to-the-newsletter/109658)

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**Author:** [@Krastanov](https://discourse.julialang.org/u/Krastanov)\
**Replies:** 0\
**Last updated:** [February 3, 2024, 3:55am UTC](https://discourse.julialang.org/t/adding-calls-for-contributors-to-the-newsletter/109658 "2024-02-03T03:55:40Z")

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Recently mentioned in a different thread: there are a lot of opportunities for junior devs to contribute and join the community and a lot of need for more maintainers (even though the bus factor for julia projects is on …

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