# Latest

**URL:** https://discourse.julialang.org/latest.md?page=552

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

**Page:** 553

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## [Improve speed of vector-jacobian product](https://discourse.julialang.org/t/improve-speed-of-vector-jacobian-product/106312)

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**Author:** [@rveltz](https://discourse.julialang.org/u/rveltz)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 6:31pm UTC](https://discourse.julialang.org/t/improve-speed-of-vector-jacobian-product/106312 "2023-11-16T18:31:59Z")

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Hi, I would like to improve some part of a code which relies on vector-jacobian product (vjp), ie computing the action of the adjoint of an operator. On my computer, the computation of vjp is ~100x slower than the evalu…

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## [Gridap.jl: Solving non-linear coupled PDEs](https://discourse.julialang.org/t/gridap-jl-solving-non-linear-coupled-pdes/106326)

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**Author:** [@charvey](https://discourse.julialang.org/u/charvey)\
**Replies:** 0\
**Last updated:** [November 16, 2023, 4:35pm UTC](https://discourse.julialang.org/t/gridap-jl-solving-non-linear-coupled-pdes/106326 "2023-11-16T16:35:56Z")

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We are having some difficulties solving two coupled multi-variate non-linear PDEs using Gridap. The various tutorials haven’t quite filled the gaps in our knowledge. We have two PDEs that we need to solve together. Thei…

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## [DifferentialEquations.jl saving p vector solution](https://discourse.julialang.org/t/differentialequations-jl-saving-p-vector-solution/106322)

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**Author:** [@CasBex](https://discourse.julialang.org/u/CasBex)\
**Replies:** 1\
**Last updated:** [November 16, 2023, 3:59pm UTC](https://discourse.julialang.org/t/differentialequations-jl-saving-p-vector-solution/106322 "2023-11-16T15:59:48Z")

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I’m currently using Functional Mockup Units (fmus) in my work and have been combining it with DifferentialEquations.jl in simulations. An FMU consists of an input, state and output, where the state comprises all variable…

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## [Unable to evaluate inputs comprising columns of either String or Int type: convert error](https://discourse.julialang.org/t/unable-to-evaluate-inputs-comprising-columns-of-either-string-or-int-type-convert-error/106035)

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**Author:** [@wilhansen](https://discourse.julialang.org/u/wilhansen)\
**Replies:** 8\
**Last updated:** [November 16, 2023, 2:30pm UTC](https://discourse.julialang.org/t/unable-to-evaluate-inputs-comprising-columns-of-either-string-or-int-type-convert-error/106035 "2023-11-16T14:30:29Z")

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Hi, I’m trying out MLJ to do decision tree regression where the inputs are categorical that are either string or ints. Below is the schema of the input (origin and destination are h3 hashes). ┌─────────────┬────────────…

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## [Julia suddenly stopped when using JuMP with Gurobi to solve](https://discourse.julialang.org/t/julia-suddenly-stopped-when-using-jump-with-gurobi-to-solve/106315)

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**Author:** [@Z\_M](https://discourse.julialang.org/u/Z_M)\
**Replies:** 6\
**Last updated:** [November 16, 2023, 1:30pm UTC](https://discourse.julialang.org/t/julia-suddenly-stopped-when-using-jump-with-gurobi-to-solve/106315 "2023-11-16T13:30:59Z")

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Hello! I have an optimization problem and I am using Gurobi solver through JuMP in Julia. In the process of solving this problem, it is necessary to constantly judge the solution add constraints, and then solve. Howeve…

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## [How to LogSumExp.jl](https://discourse.julialang.org/t/how-to-logsumexp-jl/103894)

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**Author:** [@Z\_M](https://discourse.julialang.org/u/Z_M)\
**Replies:** 3\
**Last updated:** [November 16, 2023, 11:44am UTC](https://discourse.julialang.org/t/how-to-logsumexp-jl/103894 "2023-11-16T11:44:26Z")

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Hi guys I want to calculate equations like log(a \* exp(b1) + c \* exp(b2)) I can write: logsumexp(\[log(a) + b1, log(c) + b2\]). I want to know if this method is stable. And I know that in scipy, the logsumexp functi…

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## [Using HTTP to do a post request where some parameters are JSON strings](https://discourse.julialang.org/t/using-http-to-do-a-post-request-where-some-parameters-are-json-strings/106277)

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**Author:** [@tom-plaa](https://discourse.julialang.org/u/tom-plaa)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 11:22am UTC](https://discourse.julialang.org/t/using-http-to-do-a-post-request-where-some-parameters-are-json-strings/106277 "2023-11-16T11:22:03Z")

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I’m having a problem where, when trying to write data into a server’s api using post, I cannot seem to send the correct format of json strings, i.e. without the \\" characters in between that we get when we do json(string…

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## [Any Julia package with support for 'graph6' graph encoding?](https://discourse.julialang.org/t/any-julia-package-with-support-for-graph6-graph-encoding/1893)

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**Author:** [@vsart](https://discourse.julialang.org/u/vsart)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 10:42am UTC](https://discourse.julialang.org/t/any-julia-package-with-support-for-graph6-graph-encoding/1893 "2023-11-16T10:42:08Z")

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graph6 format is a somewhat common encoding for graphs, and is available in several graph libraries/mathematical software, including NetworkX. I’m currently working on a project that would benefit from moving to Julia a…

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## [Weird interaction between packages](https://discourse.julialang.org/t/weird-interaction-between-packages/106306)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 10:25am UTC](https://discourse.julialang.org/t/weird-interaction-between-packages/106306 "2023-11-16T10:25:01Z")

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I am trying to reduce the load time of my project. What I found, using: using Timers; tic() using MAT, PyPlot function read\_lookup(varname="Tables") file = matopen(joinpath("data", "TablesCpCtCq.mat")) res = …

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## [Is there a way to block type conversion?](https://discourse.julialang.org/t/is-there-a-way-to-block-type-conversion/106302)

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**Author:** [@pao](https://discourse.julialang.org/u/pao)\
**Replies:** 6\
**Last updated:** [November 16, 2023, 9:16am UTC](https://discourse.julialang.org/t/is-there-a-way-to-block-type-conversion/106302 "2023-11-16T09:16:26Z")

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I’m writing some simple functions with combinatorial flavor (derived from IBM’s research language FL), but they cannot be used as needed by the intrusive type conversion. Example: julia\> DISTL(\[100,\[10.,20.,30.\]\]) …

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## [When I upgrade one package, another package will be downgraded. How to solve this problem?](https://discourse.julialang.org/t/when-i-upgrade-one-package-another-package-will-be-downgraded-how-to-solve-this-problem/106292)

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**Author:** [@wang\_ruoxu](https://discourse.julialang.org/u/wang_ruoxu)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 6:19am UTC](https://discourse.julialang.org/t/when-i-upgrade-one-package-another-package-will-be-downgraded-how-to-solve-this-problem/106292 "2023-11-16T06:19:32Z")

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When I upgrade SDDP@1.6.6,the will degrade ScenTrees@0.1.1，When I upgrade ScenTrees@0.3.3,the will degrade SDDP@0.4.6.What can I do to make both versions exist at the same time? I need to use these two packages at the s…

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## [QMC vs rand](https://discourse.julialang.org/t/qmc-vs-rand/106195)

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**Author:** [@tchebycheff](https://discourse.julialang.org/u/tchebycheff)\
**Replies:** 12\
**Last updated:** [November 16, 2023, 5:28am UTC](https://discourse.julialang.org/t/qmc-vs-rand/106195 "2023-11-16T05:28:19Z")

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X\_t is a d-dimensional geometric Brownian process and Y\_t = \\min\_i X\_t^{(i)}. My objective is to simulate paths of Y\_t at t=\\Delta, 2\\Delta, ..., M\\Delta. There are significant differences in E(Y\_t) estimates from QMC/S…

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## [Why ~ can not broadcast?](https://discourse.julialang.org/t/why-can-not-broadcast/106290)

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**Author:** [@zhpf0530](https://discourse.julialang.org/u/zhpf0530)\
**Replies:** 2\
**Last updated:** [November 16, 2023, 3:16am UTC](https://discourse.julialang.org/t/why-can-not-broadcast/106290 "2023-11-16T03:16:00Z")

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why ~ can not broadcast? a=randn(10) b=a.\>0 ~.b is wrong ~b is wrong map(~,b) is right.

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## [Logarithmic Smoothing - A Tutorial and Two Package Ideas](https://discourse.julialang.org/t/logarithmic-smoothing-a-tutorial-and-two-package-ideas/84877)

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**Author:** [@LostInMusic](https://discourse.julialang.org/u/LostInMusic)\
**Replies:** 8\
**Last updated:** [November 16, 2023, 3:00am UTC](https://discourse.julialang.org/t/logarithmic-smoothing-a-tutorial-and-two-package-ideas/84877 "2023-11-16T03:00:29Z")

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As a person interested in acoustics, I often plot FFT results on double-logarithmic scales. The results are often pretty noisy and smoothing is typically applied, for example with a width of 1/12 octaves. Unfortunately, …

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## [OutOfMemoryError() on large multicommodity flow model](https://discourse.julialang.org/t/outofmemoryerror-on-large-multicommodity-flow-model/106286)

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**Author:** [@nemoincognito](https://discourse.julialang.org/u/nemoincognito)\
**Replies:** 3\
**Last updated:** [November 16, 2023, 1:30am UTC](https://discourse.julialang.org/t/outofmemoryerror-on-large-multicommodity-flow-model/106286 "2023-11-16T01:30:40Z")

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I ran the code below: model = Model(HiGHS.Optimizer) # Generate a flow variable for each item in df\_flowslist1 which is ~500k items df\_flowslist1.x\_flow = @variable(model, x\[1:size(df\_flowslist1, 1)\] \>= 0) #generate a…

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## [Unsatisfiable requirements detected: MultiObjectiveAlgorithms package](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-multiobjectivealgorithms-package/106284)

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**Author:** [@kiki](https://discourse.julialang.org/u/kiki)\
**Replies:** 3\
**Last updated:** [November 16, 2023, 12:48am UTC](https://discourse.julialang.org/t/unsatisfiable-requirements-detected-multiobjectivealgorithms-package/106284 "2023-11-16T00:48:15Z")

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Hi, can you help me with the next question? I have tried to install import Pkg; Pkg.add(“MultiObjectiveAlgorithms”) But it doesn’t work, I get the message : (Before I have installed JuMP) Unsatisfiable requirements …

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## [\[ANN\] PrettyTables.jl v2.3.0 - Markdown back end](https://discourse.julialang.org/t/ann-prettytables-jl-v2-3-0-markdown-back-end/106168)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 5\
**Last updated:** [November 16, 2023, 12:10am UTC](https://discourse.julialang.org/t/ann-prettytables-jl-v2-3-0-markdown-back-end/106168 "2023-11-16T00:10:16Z")

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Hi everyone! I was a little off from the community due to some problems, but I’m back now. :slight\_smile: I want to announce that I just tagged PrettyTables.jl v2.3.0. We have some important internal improvements (like…

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## [How to improve code to compute the mean of values grouped by DateTime?](https://discourse.julialang.org/t/how-to-improve-code-to-compute-the-mean-of-values-grouped-by-datetime/106235)

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**Author:** [@Hugo](https://discourse.julialang.org/u/Hugo)\
**Replies:** 7\
**Last updated:** [November 15, 2023, 11:27pm UTC](https://discourse.julialang.org/t/how-to-improve-code-to-compute-the-mean-of-values-grouped-by-datetime/106235 "2023-11-15T23:27:37Z")

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I have written the piece of code below. It takes a vector of DateTime, a vector of Float64, and an integer g as input to calculate the mean of the the type Float64 by grouped DateTime type given time granularity g. In t…

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## [CuArrays with KrylovKit](https://discourse.julialang.org/t/cuarrays-with-krylovkit/106116)

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**Author:** [@Gattu\_Mytraya](https://discourse.julialang.org/u/Gattu_Mytraya)\
**Replies:** 8\
**Last updated:** [November 14, 2023, 10:21am UTC](https://discourse.julialang.org/t/cuarrays-with-krylovkit/106116 "2023-11-14T10:21:51Z")

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What is the recommended way of diagonalizing linear operators on CuArrays using KrylovKit? I am targeting the first 100 eigenvalues of a large matrix - Operating directly on CuArrays leads to a very large allocation on t…

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## [Error with sin and cos function after update NeuralPDE](https://discourse.julialang.org/t/error-with-sin-and-cos-function-after-update-neuralpde/102154)

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**Author:** [@Ethan\_Tran](https://discourse.julialang.org/u/Ethan_Tran)\
**Replies:** 8\
**Last updated:** [November 15, 2023, 9:50pm UTC](https://discourse.julialang.org/t/error-with-sin-and-cos-function-after-update-neuralpde/102154 "2023-11-15T21:50:41Z")

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I have updated to the latest version of package NeuralPDE and used the res = Optimization.solve(prob,OptimizationOptimJL.BFGS(); callback = callback, maxiters = 1500) to solve the ODE system on Jupyter notebook. I got th…

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## [Why does b \*= A\[r\] allocate memory?](https://discourse.julialang.org/t/why-does-b-a-r-allocate-memory/106279)

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**Author:** [@Christopher\_White](https://discourse.julialang.org/u/Christopher_White)\
**Replies:** 6\
**Last updated:** [November 15, 2023, 9:29pm UTC](https://discourse.julialang.org/t/why-does-b-a-r-allocate-memory/106279 "2023-11-15T21:29:32Z")

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The following code does a whole bunch of allocations: N = 10000000 A = randn(Float64, N) b = 1.0 @show typeof(b) @time for r = 1:N b \*= A\[r\] end Why is that? How can I write this in a way that doesn’t allocate ~ a…

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## [Memory allocations with Zygote](https://discourse.julialang.org/t/memory-allocations-with-zygote/106236)

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**Author:** [@Nikos\_Gianniotis](https://discourse.julialang.org/u/Nikos_Gianniotis)\
**Replies:** 8\
**Last updated:** [November 15, 2023, 7:40pm UTC](https://discourse.julialang.org/t/memory-allocations-with-zygote/106236 "2023-11-15T19:40:46Z")

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I have noticed that when I use Zygote to do automatic differentiation in my code (typically I use Zygote to obtain the gradient of my loss function and pass it to Opim.optimize to minimise the loss), I often get high num…

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## [Info: GAMS has launched a new language (library and API) for python](https://discourse.julialang.org/t/info-gams-has-launched-a-new-language-library-and-api-for-python/106266)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [November 15, 2023, 7:41pm UTC](https://discourse.julialang.org/t/info-gams-has-launched-a-new-language-library-and-api-for-python/106266 "2023-11-15T19:41:06Z")

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Just to share the news with you, it seems GAMS has reinvented itself today, throwing away its archaic and odd language with the launch of GAMSpy, a library (and API) to write and solve mathematical optimization models di…

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## [Optim maximization](https://discourse.julialang.org/t/optim-maximization/106274)

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**Author:** [@Longblackcoffee](https://discourse.julialang.org/u/Longblackcoffee)\
**Replies:** 1\
**Last updated:** [November 15, 2023, 6:49pm UTC](https://discourse.julialang.org/t/optim-maximization/106274 "2023-11-15T18:49:58Z")

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Hi everyone, I want to find the maximum of a function with the Optim.jl package, but I keep getting a DomainError. (I think Optim is trying to evaluate the log of a negative number) using Optim, Interpolations α = 0.4…

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## [Does anyone know an estimated number of Julia users?](https://discourse.julialang.org/t/does-anyone-know-an-estimated-number-of-julia-users/51711)

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**Author:** [@a-ill](https://discourse.julialang.org/u/a-ill)\
**Replies:** 8\
**Last updated:** [November 15, 2023, 6:40pm UTC](https://discourse.julialang.org/t/does-anyone-know-an-estimated-number-of-julia-users/51711 "2023-11-15T18:40:53Z")

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Just interested to know how many people use Julia.

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## [PlotlyJS and subplots: shared yaxis\_range](https://discourse.julialang.org/t/plotlyjs-and-subplots-shared-yaxis-range/106238)

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**Author:** [@VivMendes](https://discourse.julialang.org/u/VivMendes)\
**Replies:** 1\
**Last updated:** [November 15, 2023, 6:01pm UTC](https://discourse.julialang.org/t/plotlyjs-and-subplots-shared-yaxis-range/106238 "2023-11-15T18:01:26Z")

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Edited: now, with a MWE that can be replicated Hi, I need to create a figure with some subplots, like the following one: The code I used is this: using PlotlyJS p1 = make\_subplots(rows=2, cols=2, specs=\[Spec(…

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## [Scatter plot over a map](https://discourse.julialang.org/t/scatter-plot-over-a-map/106165)

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**Author:** [@yalonso](https://discourse.julialang.org/u/yalonso)\
**Replies:** 2\
**Last updated:** [November 15, 2023, 4:59pm UTC](https://discourse.julialang.org/t/scatter-plot-over-a-map/106165 "2023-11-15T16:59:02Z")

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Hello, I am trying to use GMT.jl to plot some points overtop a map of a region of the U.S… I can get the map to show, but when I try to scatter points over it, I’m getting an error message. Any help here would be much a…

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## [Using a Neural Network to predict the parameters of a optimization Problem](https://discourse.julialang.org/t/using-a-neural-network-to-predict-the-parameters-of-a-optimization-problem/106209)

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**Author:** [@Mkloster](https://discourse.julialang.org/u/Mkloster)\
**Replies:** 6\
**Last updated:** [November 15, 2023, 4:54pm UTC](https://discourse.julialang.org/t/using-a-neural-network-to-predict-the-parameters-of-a-optimization-problem/106209 "2023-11-15T16:54:14Z")

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Hello, i’m trying to use a neural network to predict the best parameters for a optimization problem. For this first my modell should predict some parameters based of some information i have about my optimization problem…

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## [Function only works if println statements are included](https://discourse.julialang.org/t/function-only-works-if-println-statements-are-included/106210)

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**Author:** [@opiateblush](https://discourse.julialang.org/u/opiateblush)\
**Replies:** 8\
**Last updated:** [November 15, 2023, 4:51pm UTC](https://discourse.julialang.org/t/function-only-works-if-println-statements-are-included/106210 "2023-11-15T16:51:18Z")

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Hey, I have the following piece of code that works as intended if the commented lines with the println statements are included. If they are commented out the if statement that compares the dictionaries evaluates to true …

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## [App using Dash with multi components (dcc\_dropdown and dcc\_graph) error](https://discourse.julialang.org/t/app-using-dash-with-multi-components-dcc-dropdown-and-dcc-graph-error/106269)

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**Author:** [@Siv\_Soerensen](https://discourse.julialang.org/u/Siv_Soerensen)\
**Replies:** 0\
**Last updated:** [November 15, 2023, 3:25pm UTC](https://discourse.julialang.org/t/app-using-dash-with-multi-components-dcc-dropdown-and-dcc-graph-error/106269 "2023-11-15T15:25:35Z")

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I would like to make an application in which I have both a dcc\_dropdown and a dcc\_graph component, but I do not seem to be able to get the right ‘format of the call’. I had ChatGPT make a ‘simplified version’ of my code…

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