# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1562

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

**Page:** 1563

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## [JLD load error for Dict](https://discourse.julialang.org/t/jld-load-error-for-dict/50710)

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**Author:** [@katdeane](https://discourse.julialang.org/u/katdeane)\
**Replies:** 10\
**Last updated:** [November 26, 2020, 8:23am UTC](https://discourse.julialang.org/t/jld-load-error-for-dict/50710 "2020-11-26T08:23:33Z")

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I am using dictionaries to store matrices of data under a series of tags such as the following: "GroupIdentifier"=\>Dict{Any,Any}("SubjectNumber"=\>Dict{Any,Any}("StimulusType"=\>Dict{Any,Any}("RecordingPlace"=\>(\[dat1\],\[da…

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## [How to format data for an assignment problem](https://discourse.julialang.org/t/how-to-format-data-for-an-assignment-problem/50794)

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**Author:** [@armitxe1302](https://discourse.julialang.org/u/armitxe1302)\
**Replies:** 1\
**Last updated:** [November 26, 2020, 7:37am UTC](https://discourse.julialang.org/t/how-to-format-data-for-an-assignment-problem/50794 "2020-11-26T07:37:09Z")

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Hi, I’m new to Julia and programming and general . I’m working on an assigment problem and I’m having some trouble working with DataFrames. I’m trying to create a new dataframe that consist of 2 columns from another data…

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## [Question about JuMP](https://discourse.julialang.org/t/question-about-jump/50675)

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**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 3\
**Last updated:** [November 26, 2020, 6:52am UTC](https://discourse.julialang.org/t/question-about-jump/50675 "2020-11-26T06:52:42Z")

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there is something wrong with my JuMP! It used to work!why? :persevere: thank you!

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## [How to set x-axis positions in StatPlots' violin plot?](https://discourse.julialang.org/t/how-to-set-x-axis-positions-in-statplots-violin-plot/15421)

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**Author:** [@rickhg12hs](https://discourse.julialang.org/u/rickhg12hs)\
**Replies:** 4\
**Last updated:** [September 24, 2018, 1:00pm UTC](https://discourse.julialang.org/t/how-to-set-x-axis-positions-in-statplots-violin-plot/15421 "2018-09-24T13:00:53Z")

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I’d like to create a violin plot of a DataFrame and set each “violin” at its linear respective position. For example, this plot: # some data to play with n = 10000 f(k) = randn(k) df2 = DataFrame(hcat(f(n).+1, f(n).-1, …

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## [Eigenvalues for lots of small matrices, GPU batched vs CPU eigen](https://discourse.julialang.org/t/eigenvalues-for-lots-of-small-matrices-gpu-batched-vs-cpu-eigen/50792)

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**Author:** [@arxiv](https://discourse.julialang.org/u/arxiv)\
**Replies:** 0\
**Last updated:** [November 26, 2020, 2:48am UTC](https://discourse.julialang.org/t/eigenvalues-for-lots-of-small-matrices-gpu-batched-vs-cpu-eigen/50792 "2020-11-26T02:48:31Z")

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I need to diagonalize lots of small matrices of the same size, like 50000 matrices of size 50x50, and wonder if using GPU to diagonalize them in parallel will help. So I set up a small test: using LinearAlgebra using C…

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## [Sort and collapse a vector with GPU](https://discourse.julialang.org/t/sort-and-collapse-a-vector-with-gpu/50685)

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**Author:** [@Ward9250](https://discourse.julialang.org/u/Ward9250)\
**Replies:** 3\
**Last updated:** [November 26, 2020, 2:36am UTC](https://discourse.julialang.org/t/sort-and-collapse-a-vector-with-gpu/50685 "2020-11-26T02:36:08Z")

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As my first attempt at something serious and practical I want to achieve with a GPU, I have a problem where I have an array of elements, each element is a tuple of (value, count\_of\_value). count\_of\_value is initially uni…

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## [How to implement a \`nop()\` loop for sub-µs delays? (Raspberry Pi, GPIO)](https://discourse.julialang.org/t/how-to-implement-a-nop-loop-for-sub-s-delays-raspberry-pi-gpio/50790)

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**Author:** [@notinaboat](https://discourse.julialang.org/u/notinaboat)\
**Replies:** 0\
**Last updated:** [November 26, 2020, 1:46am UTC](https://discourse.julialang.org/t/how-to-implement-a-nop-loop-for-sub-s-delays-raspberry-pi-gpio/50790 "2020-11-26T01:46:30Z")

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Hello Julia people, I’ve enjoyed using Julia for signal processing and numeric work and I’ve also tried it for some scripting and automation tasks (with mixed results, sometimes the start-up delay is a killer). I am cu…

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## [MLJ needs your testimony](https://discourse.julialang.org/t/mlj-needs-your-testimony/50784)

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**Author:** [@TheRoniOne](https://discourse.julialang.org/u/TheRoniOne)\
**Replies:** 0\
**Last updated:** [November 25, 2020, 11:54pm UTC](https://discourse.julialang.org/t/mlj-needs-your-testimony/50784 "2020-11-25T23:54:25Z")

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In The Alan Turing Institute they are reviewing the funding of MLJ and they are asking for evidence that MLJ is being used, filling a need and having an impact. In order for the project to continue seeing support, they n…

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## [Func compose(∘) is slow](https://discourse.julialang.org/t/func-compose-is-slow/50776)

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**Author:** [@novitk](https://discourse.julialang.org/u/novitk)\
**Replies:** 2\
**Last updated:** [November 25, 2020, 10:40pm UTC](https://discourse.julialang.org/t/func-compose-is-slow/50776 "2020-11-25T22:40:31Z")

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newbie here, so code\_lowered and code\_llvm is magic for me atm, but can somebody explain this pls(1.5.1)? julia\> using Dates julia\> n = 1\_000\_000 julia\> @time map(x-\>Time(Nanosecond(x)), rand(Int64, n)); 0.069440 sec…

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## [Is There a Way to Find Symbolic Roots?](https://discourse.julialang.org/t/is-there-a-way-to-find-symbolic-roots/50772)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 1\
**Last updated:** [November 25, 2020, 10:38pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-find-symbolic-roots/50772 "2020-11-25T22:38:33Z")

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I’m able to find a floating point approximation of the a second derivative, but I know the actual answer is log(a). Is there a way to find this symbolically? using ModelingToolkit using Roots p(t,a)=1/(1+a\*exp((-t))) …

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## [Blank GLMakie.jl window make system unusable while open](https://discourse.julialang.org/t/blank-glmakie-jl-window-make-system-unusable-while-open/50763)

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**Author:** [@ndinsmore](https://discourse.julialang.org/u/ndinsmore)\
**Replies:** 3\
**Last updated:** [November 25, 2020, 8:51pm UTC](https://discourse.julialang.org/t/blank-glmakie-jl-window-make-system-unusable-while-open/50763 "2020-11-25T20:51:38Z")

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Whenever I make something simple as even a large blank Makie window my system becomes unusable. For example, if I switch back to vs code it takes a good 3-4 seconds for the text to show up in the editor window, and the…

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## [Using Query.jl with an array of Dict](https://discourse.julialang.org/t/using-query-jl-with-an-array-of-dict/50770)

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**Author:** [@Peter\_Staab](https://discourse.julialang.org/u/Peter_Staab)\
**Replies:** 1\
**Last updated:** [November 25, 2020, 7:56pm UTC](https://discourse.julialang.org/t/using-query-jl-with-an-array-of-dict/50770 "2020-11-25T19:56:29Z")

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I have an array of Dicts (from JSON.jl), which I am trying to perform query commands. Here’s a shorter example though: test = \[Dict("a"=\>1,"b"=\>1),Dict("a"=\>1,"b"=\>2),Dict("a"=\>2,"b"=\>3)\] test |\> @map({\_\["a"\],\_\["b"\]}) …

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## [Multi-Threading: Threads.Atomic update value](https://discourse.julialang.org/t/multi-threading-threads-atomic-update-value/50737)

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**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 1\
**Last updated:** [November 25, 2020, 5:26pm UTC](https://discourse.julialang.org/t/multi-threading-threads-atomic-update-value/50737 "2020-11-25T17:26:25Z")

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What’s the difference between a\[\] = true and Threads.atomic\_xchg!(a, true) for a = Threads.Atomic{Bool}(false)?

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## [What is the equivalent of str() in R for Julia](https://discourse.julialang.org/t/what-is-the-equivalent-of-str-in-r-for-julia/50751)

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**Author:** [@chuymtz](https://discourse.julialang.org/u/chuymtz)\
**Replies:** 6\
**Last updated:** [November 25, 2020, 5:18pm UTC](https://discourse.julialang.org/t/what-is-the-equivalent-of-str-in-r-for-julia/50751 "2020-11-25T17:18:20Z")

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I often use str() whenever im exploring the outuut of some method in a package im getting familiar with, or i forget what a certain function was supposed to output, etc. Is there some equivalent in Julia that can be app…

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## [KeyError: key Float64 not found](https://discourse.julialang.org/t/keyerror-key-float64-not-found/50764)

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**Author:** [@ZiqinHe](https://discourse.julialang.org/u/ZiqinHe)\
**Replies:** 0\
**Last updated:** [November 25, 2020, 4:49pm UTC](https://discourse.julialang.org/t/keyerror-key-float64-not-found/50764 "2020-11-25T16:49:27Z")

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I am very new and I think my Julia works well before but after I restart the computer, I get this error how can I fix this, thank you for any help.

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## [Scraping Site](https://discourse.julialang.org/t/scraping-site/14817)

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**Author:** [@sdmcallister](https://discourse.julialang.org/u/sdmcallister)\
**Replies:** 9\
**Last updated:** [November 25, 2020, 4:41pm UTC](https://discourse.julialang.org/t/scraping-site/14817 "2020-11-25T16:41:05Z")

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I have the following simple python script that works: import requests url = "https://ABCDEFG.com/user/login" url2= "https://ABCDEFG.com/en/admin/events/page-download" payload = {'name':'FOO', 'user\_pin':'1…

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## [BinaryBuilder cross-coompilation env needs an additional library](https://discourse.julialang.org/t/binarybuilder-cross-coompilation-env-needs-an-additional-library/50505)

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**Author:** [@Mikhail\_Kagalenko](https://discourse.julialang.org/u/Mikhail_Kagalenko)\
**Replies:** 12\
**Last updated:** [November 25, 2020, 4:28pm UTC](https://discourse.julialang.org/t/binarybuilder-cross-coompilation-env-needs-an-additional-library/50505 "2020-11-25T16:28:46Z")

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I am trying to include a C++ library with julia package. After BinaryBuilder’s wizard drops me into cross-compilation environment, the configure script that I sun within the source directory informs me that I need an add…

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## [Sample from Kernel Density Estimator](https://discourse.julialang.org/t/sample-from-kernel-density-estimator/50639)

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**Author:** [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Replies:** 3\
**Last updated:** [November 25, 2020, 3:59pm UTC](https://discourse.julialang.org/t/sample-from-kernel-density-estimator/50639 "2020-11-25T15:59:04Z")

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From a sample of data I can create a KDE to estimate the probability density with KernelDensity.jl, e.g.: density\_estimator = kde(data) Now, is there any package or custom code that I could use to retrieve a sample fro…

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## [Windows file path string (slash direction, best way to copy/paste)](https://discourse.julialang.org/t/windows-file-path-string-slash-direction-best-way-to-copy-paste/29204)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 5\
**Last updated:** [November 25, 2020, 1:49pm UTC](https://discourse.julialang.org/t/windows-file-path-string-slash-direction-best-way-to-copy-paste/29204 "2020-11-25T13:49:21Z")

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One of the most annoying things that I do on a daily basis (on my Windows 10 machine) is finding a path to a file that has some data that I want to bring into my program, right-clicking it, clicking ‘Properties’ and then…

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## [Mutation and recombination rate of DE algorithm in BlackBoxOptim](https://discourse.julialang.org/t/mutation-and-recombination-rate-of-de-algorithm-in-blackboxoptim/50726)

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**Author:** [@yusri-dh](https://discourse.julialang.org/u/yusri-dh)\
**Replies:** 2\
**Last updated:** [November 25, 2020, 1:45pm UTC](https://discourse.julialang.org/t/mutation-and-recombination-rate-of-de-algorithm-in-blackboxoptim/50726 "2020-11-25T13:45:43Z")

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Is there any way to know and change the mutation and recombination rate of the differential evolution algorithm in BlackBoxOptim?

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## [Why cglobal() in BigInt finalizer?](https://discourse.julialang.org/t/why-cglobal-in-bigint-finalizer/50740)

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**Author:** [@Mikhail\_Kagalenko](https://discourse.julialang.org/u/Mikhail_Kagalenko)\
**Replies:** 3\
**Last updated:** [November 25, 2020, 12:50pm UTC](https://discourse.julialang.org/t/why-cglobal-in-bigint-finalizer/50740 "2020-11-25T12:50:59Z")

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Looking at gmp.jl source, I noticed that the finalizer in BigInt definition uses cglobal to get the (I assume) function pointer: function BigInt(; nbits::Integer=0) b = MPZ.init2!(new(), nbits) finalizer…

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## [Pkg test CUDA on Windows 10, Julia 1.5.2](https://discourse.julialang.org/t/pkg-test-cuda-on-windows-10-julia-1-5-2/49209)

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**Author:** [@arxiv](https://discourse.julialang.org/u/arxiv)\
**Replies:** 2\
**Last updated:** [November 25, 2020, 12:32pm UTC](https://discourse.julialang.org/t/pkg-test-cuda-on-windows-10-julia-1-5-2/49209 "2020-11-25T12:32:12Z")

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I just added CUDA.jl and ran Pkg test, did not pass. Wonder what the issue is. Machine info: Windows 10, GeForce MX150 Julia version info: Julia Version 1.5.2 Commit 539f3ce943 (2020-09-23 23:17 UTC) Platform Info: …

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## [Looking for a Flux RNN tutorial](https://discourse.julialang.org/t/looking-for-a-flux-rnn-tutorial/50743)

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**Author:** [@HenriDeh](https://discourse.julialang.org/u/HenriDeh)\
**Replies:** 0\
**Last updated:** [November 25, 2020, 11:34am UTC](https://discourse.julialang.org/t/looking-for-a-flux-rnn-tutorial/50743 "2020-11-25T11:34:29Z")

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Hello, I’m following a DL reading seminar with some PhD students. We follow the book Dive into Deep Learning but the code is written in Python. As a good exercise, and since I’m a julia user, I’m moving all the implemen…

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## [Plots: JuliaGraphics / Colors.jl removing the guess of colours](https://discourse.julialang.org/t/plots-juliagraphics-colors-jl-removing-the-guess-of-colours/50010)

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**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 9\
**Last updated:** [November 25, 2020, 11:19am UTC](https://discourse.julialang.org/t/plots-juliagraphics-colors-jl-removing-the-guess-of-colours/50010 "2020-11-25T11:19:04Z")

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We are ever so grateful of having such a great variety of colour options in Plots which is great for publications. But the question is how can we get a preview of the colour before trying them out? Colours # This is t…

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## [DataFrame conversion of column names to type](https://discourse.julialang.org/t/dataframe-conversion-of-column-names-to-type/50694)

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**Author:** [@optimist](https://discourse.julialang.org/u/optimist)\
**Replies:** 5\
**Last updated:** [November 25, 2020, 11:05am UTC](https://discourse.julialang.org/t/dataframe-conversion-of-column-names-to-type/50694 "2020-11-25T11:05:46Z")

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I use DataFrames to read a CSV file. I need to determine the number of columns with the header dates (e.g. 01/10/2020) and extract those column names and convert their type to Date. In my MWE, I have shown two methods t…

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## [Pass optional parameters to model in DifferentialEquations.jl](https://discourse.julialang.org/t/pass-optional-parameters-to-model-in-differentialequations-jl/50718)

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**Author:** [@claudio20497](https://discourse.julialang.org/u/claudio20497)\
**Replies:** 2\
**Last updated:** [November 25, 2020, 8:59am UTC](https://discourse.julialang.org/t/pass-optional-parameters-to-model-in-differentialequations-jl/50718 "2020-11-25T08:59:51Z")

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Hello, I would like to pass optional arguments to a DifferentialEquations.jl ODE model at ODEProblem time. Those optional arguments are meant to alter the model without using the p argument which I would like to save fo…

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## [Unpacking binary data into a Julia struct](https://discourse.julialang.org/t/unpacking-binary-data-into-a-julia-struct/32941)

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**Author:** [@tlnagy](https://discourse.julialang.org/u/tlnagy)\
**Replies:** 7\
**Last updated:** [November 25, 2020, 8:43am UTC](https://discourse.julialang.org/t/unpacking-binary-data-into-a-julia-struct/32941 "2020-11-25T08:43:17Z")

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I’m having a hard time finding an example in Julia v1.0+ for handling unpacking binary data into a Julia struct. Is there an easy way to do this? Say I have some custom struct Test and wanted to read some binary data fr…

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## [Debugging of julia modules lead to errors while evaluating not](https://discourse.julialang.org/t/debugging-of-julia-modules-lead-to-errors-while-evaluating-not/50036)

<div class="topic-metadata">

**Author:** [@Volker](https://discourse.julialang.org/u/Volker)\
**Replies:** 7\
**Last updated:** [November 25, 2020, 8:10am UTC](https://discourse.julialang.org/t/debugging-of-julia-modules-lead-to-errors-while-evaluating-not/50036 "2020-11-25T08:10:19Z")

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Hi, I often would like to debug the code of some julia modules i.e. DiffEqFlux or Flux to better understand what is going on, but some how I get error messages during debugging, which I don´t get when I just evaluate th…

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## [Saving functions with JLD2](https://discourse.julialang.org/t/saving-functions-with-jld2/50717)

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**Author:** [@SamBrand](https://discourse.julialang.org/u/SamBrand)\
**Replies:** 2\
**Last updated:** [November 25, 2020, 8:01am UTC](https://discourse.julialang.org/t/saving-functions-with-jld2/50717 "2020-11-25T08:01:43Z")

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Hi all, I am currently engaged in modelling/forecasting SARS-CoV-2 transmission (like everyone else it feels like…). My current work flow involves parameter inference, and I contain all the relevant information about w…

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## [How to save plots early and plot them together on same axes later?](https://discourse.julialang.org/t/how-to-save-plots-early-and-plot-them-together-on-same-axes-later/50467)

<div class="topic-metadata">

**Author:** [@CosmoProf](https://discourse.julialang.org/u/CosmoProf)\
**Replies:** 4\
**Last updated:** [November 25, 2020, 6:18am UTC](https://discourse.julialang.org/t/how-to-save-plots-early-and-plot-them-together-on-same-axes-later/50467 "2020-11-25T06:18:37Z")

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Hi again good folks, I’ve got another question about something that seems simple, but I can’t figure out how to do it after much searching. I’m trying to have a delayed-effect version of what you normally get with comman…

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