# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1004

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

**Page:** 1005

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## [Taking TTFX seriously: Can we make common packages faster to load and use](https://discourse.julialang.org/t/taking-ttfx-seriously-can-we-make-common-packages-faster-to-load-and-use/74949)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 123\
**Last updated:** [June 20, 2022, 6:19pm UTC](https://discourse.julialang.org/t/taking-ttfx-seriously-can-we-make-common-packages-faster-to-load-and-use/74949 "2022-06-20T18:19:12Z")

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So much work has been done to improve julia compilation and remove invalidations. Things really feel a lot snappier to use. But there is still the problem of packages that were written without much thought to startup ti…

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## [Flow conservation constraint](https://discourse.julialang.org/t/flow-conservation-constraint/83075)

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**Author:** [@Takashy](https://discourse.julialang.org/u/Takashy)\
**Replies:** 3\
**Last updated:** [June 20, 2022, 5:38pm UTC](https://discourse.julialang.org/t/flow-conservation-constraint/83075 "2022-06-20T17:38:10Z")

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Hi there! I’m trying to write a flow conservation constrains. Yet it says key not found # this is the constraint I'd like to write (and α(i,j) is a binary variable and A1 is a subset of nodes) ∑ᵢ α\[i,j\] = ∑ₖ α\[j,k\] …

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## [\[ANN\] OhMyArtifacts.jl](https://discourse.julialang.org/t/ann-ohmyartifacts-jl/83026)

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**Author:** [@chengchingwen](https://discourse.julialang.org/u/chengchingwen)\
**Replies:** 16\
**Last updated:** [June 20, 2022, 5:13pm UTC](https://discourse.julialang.org/t/ann-ohmyartifacts-jl/83026 "2022-06-20T17:13:34Z")

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I’m excited to announce OhMyArtifacts.jl, a dynamic artifact system that lives in scratchspace. It has API similar to Artifacts.jl, but it use sha256 hash and cache every files. The usage of each cache is tracked, so it …

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## [\`First function call produced NaNs\` when using NUTS but not MH](https://discourse.julialang.org/t/first-function-call-produced-nans-when-using-nuts-but-not-mh/83024)

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**Author:** [@jacobusmmsmit](https://discourse.julialang.org/u/jacobusmmsmit)\
**Replies:** 7\
**Last updated:** [June 20, 2022, 4:29pm UTC](https://discourse.julialang.org/t/first-function-call-produced-nans-when-using-nuts-but-not-mh/83024 "2022-06-20T16:29:16Z")

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Hello everyone, I’m having trouble fitting a Cucker-Smaile ODE model with Turing. \\Psi is positive, non-increasing and smooth, in my model ψ(r, K, β) = K / ((1 + r^2)^β). Even though I can solve the ODE system fine,…

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## [Allocation with Subset of Matrix and Views](https://discourse.julialang.org/t/allocation-with-subset-of-matrix-and-views/82998)

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**Author:** [@TI36XPro](https://discourse.julialang.org/u/TI36XPro)\
**Replies:** 2\
**Last updated:** [June 20, 2022, 4:04pm UTC](https://discourse.julialang.org/t/allocation-with-subset-of-matrix-and-views/82998 "2022-06-20T16:04:31Z")

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Hello, I’m wondering if anyone can help me understand the following. I want to replace a subset of matrix A with matrix B. I understand this can be done efficiently using for loops or copyto!. I am specifically interest…

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## [Animation and File Size](https://discourse.julialang.org/t/animation-and-file-size/82972)

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**Author:** [@Mahmoud](https://discourse.julialang.org/u/Mahmoud)\
**Replies:** 3\
**Last updated:** [June 20, 2022, 3:32pm UTC](https://discourse.julialang.org/t/animation-and-file-size/82972 "2022-06-20T15:32:35Z")

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this code generates error and I know why Is there a way to get over it I need to animate each 100 steps because the file size reach 1GB with each step animation How to generate animation with small file size given tha…

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## [Slices: should they default to views?](https://discourse.julialang.org/t/slices-should-they-default-to-views/83023)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 11\
**Last updated:** [June 20, 2022, 3:27pm UTC](https://discourse.julialang.org/t/slices-should-they-default-to-views/83023 "2022-06-20T15:27:23Z")

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I wonder what is more common, slicing a matrix to create a copy of the entries, or to create a view? If we desire the latter, we have to do @views. But if the latter is the more common use, wouldn’t it be nice to dispens…

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## [How to multiply tuples and how to change a format of summation?](https://discourse.julialang.org/t/how-to-multiply-tuples-and-how-to-change-a-format-of-summation/82928)

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**Author:** [@Kevin\_12](https://discourse.julialang.org/u/Kevin_12)\
**Replies:** 2\
**Last updated:** [June 20, 2022, 3:03pm UTC](https://discourse.julialang.org/t/how-to-multiply-tuples-and-how-to-change-a-format-of-summation/82928 "2022-06-20T15:03:24Z")

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If you have a set A = \[ (1,4,7), (2,5,3), (5,4,9), (2,8,7), (8,6,7), (2,3,5) \] .Is it possible to derive: #1 another set A' such that A' = 1.2\*A each element of A' is the scaled version of A #2 define a variable …

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## [Groupby search not working as expected](https://discourse.julialang.org/t/groupby-search-not-working-as-expected/83035)

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**Author:** [@anon69491625](https://discourse.julialang.org/u/anon69491625)\
**Replies:** 9\
**Last updated:** [June 20, 2022, 2:53pm UTC](https://discourse.julialang.org/t/groupby-search-not-working-as-expected/83035 "2022-06-20T14:53:04Z")

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slowly working my way through RElearning dataframes ( from pandas ) and wanted to search a dataframe for a value. This is a search I will be doing many times so I thought the approach below might speed things up. using …

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## [Failed to plot](https://discourse.julialang.org/t/failed-to-plot/83002)

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**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 2\
**Last updated:** [June 20, 2022, 2:38pm UTC](https://discourse.julialang.org/t/failed-to-plot/83002 "2022-06-20T14:38:55Z")

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I have added the PLots.jl But when I use it to plot.It shows me such wrong. using Plots plot(\[1,2,3\]) ERROR: LoadError: UndefVarError: plot not defined Stacktrace: \[1\] top-level scope at untitled-752712825fa0b1fb343e…

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## [Evaluate variable-length input array RNN in Julia Flux](https://discourse.julialang.org/t/evaluate-variable-length-input-array-rnn-in-julia-flux/82475)

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**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 4\
**Last updated:** [June 20, 2022, 1:19pm UTC](https://discourse.julialang.org/t/evaluate-variable-length-input-array-rnn-in-julia-flux/82475 "2022-06-20T13:19:59Z")

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How to create a vector of a matrice for variable sequence length data to evaluate untrained RNN? Following the idea developed in these \[link1, link2\] it is possible to carry out the evaluation for a vector; using Flux …

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## [Julia precompilation limits or are there really any?](https://discourse.julialang.org/t/julia-precompilation-limits-or-are-there-really-any/55224)

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**Author:** [@Marcell\_Havlik](https://discourse.julialang.org/u/Marcell_Havlik)\
**Replies:** 20\
**Last updated:** [June 20, 2022, 1:19pm UTC](https://discourse.julialang.org/t/julia-precompilation-limits-or-are-there-really-any/55224 "2022-06-20T13:19:17Z")

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Hey, I tried to read every details on this topic but I still can’t be sure about what is the limiting factor at reaching “nocompilation” speed. (Under no compilation speed I mean the speed when you second time run the a…

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## [Parallelization of Sum in JuMP](https://discourse.julialang.org/t/parallelization-of-sum-in-jump/82979)

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**Author:** [@LukasBarner](https://discourse.julialang.org/u/LukasBarner)\
**Replies:** 2\
**Last updated:** [June 20, 2022, 1:02pm UTC](https://discourse.julialang.org/t/parallelization-of-sum-in-jump/82979 "2022-06-20T13:02:54Z")

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Hi everyone, I am writing a JuMP model, which has a quadratic term in the objective function. It looks something like the following: @expression(model, term, sum( ( a\[i\] - b\[i\] \* sum( x\[(i,j2)\] for j2 in dict\_j\[i\] ) )\*…

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## [Overcoming performance hit of accessing struct field](https://discourse.julialang.org/t/overcoming-performance-hit-of-accessing-struct-field/82911)

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**Author:** [@f.ij](https://discourse.julialang.org/u/f.ij)\
**Replies:** 11\
**Last updated:** [June 20, 2022, 12:18pm UTC](https://discourse.julialang.org/t/overcoming-performance-hit-of-accessing-struct-field/82911 "2022-06-20T12:18:31Z")

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Hi all, I’m working on a simulator for a Monte Carlo simulation of a spin ising model. I was working with a custom struct holding a few arrays and dicts. As an example, one of the arrays holds 512^2 Int8’s, which repres…

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## [Pluto: how to number equations in LaTeX mode](https://discourse.julialang.org/t/pluto-how-to-number-equations-in-latex-mode/59900)

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**Author:** [@VivMendes](https://discourse.julialang.org/u/VivMendes)\
**Replies:** 21\
**Last updated:** [June 20, 2022, 11:50am UTC](https://discourse.julialang.org/t/pluto-how-to-number-equations-in-latex-mode/59900 "2022-06-20T11:50:48Z")

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Maybe I am missing some similar post already raised before. I have done my best, looking for such a topic, but I haven’t found one. How can I number an equation (written in LaTeX mode) in Pluto? The quality of the LaTeX …

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## [How to print markdown in the terminal](https://discourse.julialang.org/t/how-to-print-markdown-in-the-terminal/82397)

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**Author:** [@dylanxyz](https://discourse.julialang.org/u/dylanxyz)\
**Replies:** 14\
**Last updated:** [June 20, 2022, 11:24am UTC](https://discourse.julialang.org/t/how-to-print-markdown-in-the-terminal/82397 "2022-06-20T11:24:50Z")

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I want to print styled markdown with colors and etc (the same way the REPL prints docs), instead of the raw text. So far i wasn’t able to figure out, i was thinking something like: show(stdout, MIME"text/markdown", some…

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## [How to get within r2 and t value from FixedEffectModels?](https://discourse.julialang.org/t/how-to-get-within-r2-and-t-value-from-fixedeffectmodels/83055)

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**Author:** [@Raymond](https://discourse.julialang.org/u/Raymond)\
**Replies:** 0\
**Last updated:** [June 20, 2022, 10:04am UTC](https://discourse.julialang.org/t/how-to-get-within-r2-and-t-value-from-fixedeffectmodels/83055 "2022-06-20T10:04:40Z")

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Dear all, how to get within\_r2 and t value? julia\> using DataFrames, DataFramesMeta, FixedEffectModels julia\> df = dataset("plm", "GrunFeld"); julia\> fe1 = reg(df, @formula(Inv ~ Value + Capital + fe(Firm))) …

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## [How to simulate \`for\_each\_yaxis\` (from Python) in Julia?](https://discourse.julialang.org/t/how-to-simulate-for-each-yaxis-from-python-in-julia/75539)

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**Author:** [@Mo-Gul](https://discourse.julialang.org/u/Mo-Gul)\
**Replies:** 1\
**Last updated:** [June 20, 2022, 9:41am UTC](https://discourse.julialang.org/t/how-to-simulate-for-each-yaxis-from-python-in-julia/75539 "2022-06-20T09:41:53Z")

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The title says it all (again). Currently I state all the axes manually to change their styles like in p = make\_subplots( rows=2, cols=1, shared\_xaxes=true, ); add\_trace!(p, scatter(y=1:2), row=1, col=1…

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## [Using the type and functions for dispatch purposes without loading all codes of its owner package](https://discourse.julialang.org/t/using-the-type-and-functions-for-dispatch-purposes-without-loading-all-codes-of-its-owner-package/79951)

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**Author:** [@JohnnyChen94](https://discourse.julialang.org/u/JohnnyChen94)\
**Replies:** 9\
**Last updated:** [June 20, 2022, 8:25am UTC](https://discourse.julialang.org/t/using-the-type-and-functions-for-dispatch-purposes-without-loading-all-codes-of-its-owner-package/79951 "2022-06-20T08:25:37Z")

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Like C/C++'s header file, I’m wondering if it’s possible for Julia to introduce similar concepts so that package authors can have a smaller dependencies and thus reduce the latency. In valid Julia semantics, this can be…

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## [Base operator on custom array](https://discourse.julialang.org/t/base-operator-on-custom-array/83042)

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**Author:** [@Brian1](https://discourse.julialang.org/u/Brian1)\
**Replies:** 5\
**Last updated:** [June 20, 2022, 8:08am UTC](https://discourse.julialang.org/t/base-operator-on-custom-array/83042 "2022-06-20T08:08:26Z")

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Here I define a struct struct Df{T,N} \<: AbstractArray{T,N} value::AbstractArray{T,N} end Base.size(df::Df)=size(df.value) Base.getindex(df::Df,i...)=Df(df.value\[i...\]) Base.getindex(df::Df,i::Union{Int,Cartesian…

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## [How to make colors faint/transparent when plotting a color plane using Plots?](https://discourse.julialang.org/t/how-to-make-colors-faint-transparent-when-plotting-a-color-plane-using-plots/83017)

<div class="topic-metadata">

**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 2\
**Last updated:** [June 20, 2022, 8:08am UTC](https://discourse.julialang.org/t/how-to-make-colors-faint-transparent-when-plotting-a-color-plane-using-plots/83017 "2022-06-20T08:08:25Z")

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Hello, I want to plot a colour plane using plots, e.g. using Plots plot(\[RGB{Float64}(0.0,0.0,1.0) RGB{Float64}(1.0,0.0,0.0); RGB{Float64}(1.0,0.0,0.0) RGB{Float64}(1.0,0.0,0.0)\]) Is there a way to make this faint/t…

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## [Default v.s. inner constructor changes dispatch?](https://discourse.julialang.org/t/default-v-s-inner-constructor-changes-dispatch/83036)

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**Author:** [@tictaccat](https://discourse.julialang.org/u/tictaccat)\
**Replies:** 6\
**Last updated:** [June 20, 2022, 6:53am UTC](https://discourse.julialang.org/t/default-v-s-inner-constructor-changes-dispatch/83036 "2022-06-20T06:53:55Z")

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I’m running into an inconsistency between default and inner constructors and have tried to construct an MWE below. Consider code version a) struct MyType{V} x::V y::Int64 end MyType{V}(x::V, y::Real) where …

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## [Does anybody use the syntax \`a \<operator\> b = ...\` to define new methods for operators?](https://discourse.julialang.org/t/does-anybody-use-the-syntax-a-operator-b-to-define-new-methods-for-operators/83034)

<div class="topic-metadata">

**Author:** [@dylanxyz](https://discourse.julialang.org/u/dylanxyz)\
**Replies:** 8\
**Last updated:** [June 20, 2022, 4:09am UTC](https://discourse.julialang.org/t/does-anybody-use-the-syntax-a-operator-b-to-define-new-methods-for-operators/83034 "2022-06-20T04:09:28Z")

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I know that the julia docs mentions that operators are just regular functions that have a special syntax, so the expressions a \<operator\> b and \<operator\>(a, b) are equivalent. What i did not realized, is that we can use…

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## [Matrix multiplication in summation form](https://discourse.julialang.org/t/matrix-multiplication-in-summation-form/83020)

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**Author:** [@horvetz](https://discourse.julialang.org/u/horvetz)\
**Replies:** 8\
**Last updated:** [June 20, 2022, 4:00am UTC](https://discourse.julialang.org/t/matrix-multiplication-in-summation-form/83020 "2022-06-20T04:00:53Z")

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How to write an explicit one-line code for matrix multiplication A\*B, each of size n by n, for example using the summation definition of matrix multiplication (here, eq 14)? I know how to do it for matrix-vector multipl…

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## [Symbolics istree returning false when there is a tree](https://discourse.julialang.org/t/symbolics-istree-returning-false-when-there-is-a-tree/82993)

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**Author:** [@infiniteFun](https://discourse.julialang.org/u/infiniteFun)\
**Replies:** 4\
**Last updated:** [June 20, 2022, 1:29am UTC](https://discourse.julialang.org/t/symbolics-istree-returning-false-when-there-is-a-tree/82993 "2022-06-20T01:29:00Z")

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Hello, I have the following scenario that I’m unable to understand in Symbolics. It would be great if somebody could help me with that: using ModelingToolkit @variables t x(t) D = Differential(t) eqs = \[D(x) ~ x\] eq…

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## [Massive performance penalty for Float16 compared to Float32](https://discourse.julialang.org/t/massive-performance-penalty-for-float16-compared-to-float32/6864)

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**Author:** [@zenon](https://discourse.julialang.org/u/zenon)\
**Replies:** 17\
**Last updated:** [June 20, 2022, 1:15am UTC](https://discourse.julialang.org/t/massive-performance-penalty-for-float16-compared-to-float32/6864 "2022-06-20T01:15:29Z")

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Hello, I just do the Coursera lectures about Deep Leanring by Andrew Ng, and want to implement what I learned in Julia (lecture is in Python), so I can check my understanding. So there is a small neural net, and it take…

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## [GLMakie Menu() maximum number of items?](https://discourse.julialang.org/t/glmakie-menu-maximum-number-of-items/82948)

<div class="topic-metadata">

**Author:** [@garrek](https://discourse.julialang.org/u/garrek)\
**Replies:** 6\
**Last updated:** [June 20, 2022, 12:18am UTC](https://discourse.julialang.org/t/glmakie-menu-maximum-number-of-items/82948 "2022-06-20T00:18:01Z")

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Is there a maximum number of items that can be added to a Menu? I’m experimenting with GLMakie and Observables. My program watches a folder for new files. Both the data and Menu options are Observables, so when a new fil…

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## [Interactive/Animated graphics a-la scratch.mit.edu?](https://discourse.julialang.org/t/interactive-animated-graphics-a-la-scratch-mit-edu/40772)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 13\
**Last updated:** [June 20, 2022, 12:12am UTC](https://discourse.julialang.org/t/interactive-animated-graphics-a-la-scratch-mit-edu/40772 "2022-06-20T00:12:52Z")

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Suppose someone wanted to teach computer programming concepts using Julia through interactive graphical animations a-la scratch? Are there any packages that let you open a window and draw objects/move them around/animate…

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## [Handling SIGTERM in Julia](https://discourse.julialang.org/t/handling-sigterm-in-julia/32231)

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**Author:** [@josuagrw](https://discourse.julialang.org/u/josuagrw)\
**Replies:** 9\
**Last updated:** [June 19, 2022, 11:47pm UTC](https://discourse.julialang.org/t/handling-sigterm-in-julia/32231 "2022-06-19T23:47:21Z")

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Hi, from researching a bit I learned that handling unix signals has been tricky in Julia for a while. Our queuing systems send signals to programs to indicate they should come to an end; and I’d like to do stuff like sto…

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## [Blog post about my experiences with Julia](https://discourse.julialang.org/t/blog-post-about-my-experiences-with-julia/79976)

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**Author:** [@Volker\_Weissmann](https://discourse.julialang.org/u/Volker_Weissmann)\
**Replies:** 258\
**Last updated:** [June 19, 2022, 11:16pm UTC](https://discourse.julialang.org/t/blog-post-about-my-experiences-with-julia/79976 "2022-06-19T23:16:57Z")

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I used Julia for a while and wrote a blog post about it: What do you think about this post?

[Previous page](https://discourse.julialang.org/latest.md?page=1003)

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