# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=382

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**Page:** 383

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## [Incorrect (implicit) gradients for a custom model in Flux](https://discourse.julialang.org/t/incorrect-implicit-gradients-for-a-custom-model-in-flux/56902)

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**Author:** [@arlk](https://discourse.julialang.org/u/arlk)\
**Replies:** 3\
**Last updated:** [March 12, 2021, 10:28pm UTC](https://discourse.julialang.org/t/incorrect-implicit-gradients-for-a-custom-model-in-flux/56902 "2021-03-12T22:28:53Z")

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I’m seeing incorrectly computed gradients when I use a vector of matrices as a model in Flux. The implicit gradients compute to 0 but the structural gradients seem to be computed correctly. MWE: using Flux struct Veco…

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## [How to use heatmap(values)?](https://discourse.julialang.org/t/how-to-use-heatmap-values/57043)

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**Author:** [@jzr](https://discourse.julialang.org/u/jzr)\
**Replies:** 1\
**Last updated:** [March 12, 2021, 8:36pm UTC](https://discourse.julialang.org/t/how-to-use-heatmap-values/57043 "2021-03-12T20:36:21Z")

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heatmap has a heatmap(values) function but there isn’t an example for it in the docs. How can I use it?

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## [Getting Oriented](https://discourse.julialang.org/t/getting-oriented/56970)

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**Author:** [@Ross\_Boylan](https://discourse.julialang.org/u/Ross_Boylan)\
**Replies:** 6\
**Last updated:** [March 12, 2021, 7:09pm UTC](https://discourse.julialang.org/t/getting-oriented/56970 "2021-03-12T19:09:11Z")

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The introduction to the optimization topic in discourse refers to http://www.juliaopt.org/, but that site declares itself to be dead and obsolete, while referencing https://jump.dev/. But the latter does not appear to b…

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## [Makie: New Figure w/ multiple LScenes auto-resizing when undesired](https://discourse.julialang.org/t/makie-new-figure-w-multiple-lscenes-auto-resizing-when-undesired/56975)

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**Author:** [@zobot](https://discourse.julialang.org/u/zobot)\
**Replies:** 6\
**Last updated:** [March 12, 2021, 6:44pm UTC](https://discourse.julialang.org/t/makie-new-figure-w-multiple-lscenes-auto-resizing-when-undesired/56975 "2021-03-12T18:44:43Z")

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Hi, I’m trying to learn the new Figure system to combine animated LScenes with contour plots. I generate a curve for the camera eyepos and lookat and values for the plots for each frame. I’ve figured out all of that but …

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## [Nicer parameter indexing](https://discourse.julialang.org/t/nicer-parameter-indexing/50704)

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**Author:** [@ohmsweetohm1](https://discourse.julialang.org/u/ohmsweetohm1)\
**Replies:** 3\
**Last updated:** [March 12, 2021, 5:21pm UTC](https://discourse.julialang.org/t/nicer-parameter-indexing/50704 "2021-03-12T17:21:29Z")

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Consider the following example: import Plots using ModelingToolkit, DifferentialEquations @parameters t σ ρ β @variables x(t) y(t) z(t) @derivatives D'~t eqs = \[D(x) ~ σ \* (y - x), D(y) ~ x \* (ρ - z) - y, …

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## [JuMP/CPLEX: how to set heuristic solution using SparseAxisArrays in callback](https://discourse.julialang.org/t/jump-cplex-how-to-set-heuristic-solution-using-sparseaxisarrays-in-callback/56938)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 2\
**Last updated:** [March 12, 2021, 9:04am UTC](https://discourse.julialang.org/t/jump-cplex-how-to-set-heuristic-solution-using-sparseaxisarrays-in-callback/56938 "2021-03-12T09:04:43Z")

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Dear folks, unfortunately I fail to submit a heuristic solution using SparseAxisArrays in a callback. Here is an MWE: using JuMP, CPLEX model = JuMP.direct\_model( CPLEX.Optimizer() ) set\_optimizer\_attribute( model, "C…

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## [Warning invalid warm start GLPK](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441)

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**Author:** [@ErwanPiR](https://discourse.julialang.org/u/ErwanPiR)\
**Replies:** 3\
**Last updated:** [March 11, 2021, 2:20am UTC](https://discourse.julialang.org/t/warning-invalid-warm-start-glpk/46441 "2021-03-11T02:20:50Z")

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Hi, I see some topics dated from 2019 talking about the warm start in JuMP with GLPK. I still have the warning : Warning: MathOptInterface.VariablePrimalStart() is not supported by MathOptInterface.Bridges.LazyBridgeOp…

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## [In JuMP, how to access a named constraint created inside a function](https://discourse.julialang.org/t/in-jump-how-to-access-a-named-constraint-created-inside-a-function/56912)

<div class="topic-metadata">

**Author:** [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Replies:** 2\
**Last updated:** [March 10, 2021, 10:54pm UTC](https://discourse.julialang.org/t/in-jump-how-to-access-a-named-constraint-created-inside-a-function/56912 "2021-03-10T22:54:02Z")

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I would like to delete a constraint created inside a function. For example, function mymodel(a) m = Model() @variable(model, w\[1:n\] \>= 0) @constraint(model, budget, sum(w) == a) ... return m end …

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## [Multidimensional integration and differentiation](https://discourse.julialang.org/t/multidimensional-integration-and-differentiation/56163)

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**Author:** [@simonf](https://discourse.julialang.org/u/simonf)\
**Replies:** 3\
**Last updated:** [March 10, 2021, 10:42pm UTC](https://discourse.julialang.org/t/multidimensional-integration-and-differentiation/56163 "2021-03-10T22:42:11Z")

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Hi, I have a series of parameterized functions containing double integrals and function limits and want to find stationary points of those functions. I have a solution using SymPy.jl, but this is only working well for k…

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## [Question about write.to.file with .lp (JuMP context)](https://discourse.julialang.org/t/question-about-write-to-file-with-lp-jump-context/56892)

<div class="topic-metadata">

**Author:** [@felcbd](https://discourse.julialang.org/u/felcbd)\
**Replies:** 1\
**Last updated:** [March 10, 2021, 7:40pm UTC](https://discourse.julialang.org/t/question-about-write-to-file-with-lp-jump-context/56892 "2021-03-10T19:40:35Z")

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Hi everyone, I had a question about a practice case I actually have with the write.to.file function. I have my model writed with JuMP and I want to solve it with CPLEX directly from my .jl file with !optimize, and I ha…

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## [Spectral acceleration](https://discourse.julialang.org/t/spectral-acceleration/56895)

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**Author:** [@Frederic\_Gilt](https://discourse.julialang.org/u/Frederic_Gilt)\
**Replies:** 0\
**Last updated:** [March 10, 2021, 3:52pm UTC](https://discourse.julialang.org/t/spectral-acceleration/56895 "2021-03-10T15:52:50Z")

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Dear community, I have accelerations ai during each time step ti for a given time range \[ai ti\] as raw datas and was wondering if Julia has some already prepared spectral acceleration tool… If not I have a pseudo-code …

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## [ForwardDiff evaluation of objective in Optim returns wrong result (objective uses DifferentialEquations pkg)](https://discourse.julialang.org/t/forwarddiff-evaluation-of-objective-in-optim-returns-wrong-result-objective-uses-differentialequations-pkg/54624)

<div class="topic-metadata">

**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 7\
**Last updated:** [March 10, 2021, 3:38pm UTC](https://discourse.julialang.org/t/forwarddiff-evaluation-of-objective-in-optim-returns-wrong-result-objective-uses-differentialequations-pkg/54624 "2021-03-10T15:38:52Z")

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I am having a strange problem with ForwardDiff that is internally used in Optim. The minimum returned by Optim is not the same value as the value of the objective function when the minimizer returned by Optim is used, se…

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## [FFT planning with flags fails for CUDA](https://discourse.julialang.org/t/fft-planning-with-flags-fails-for-cuda/56870)

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**Author:** [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)\
**Replies:** 2\
**Last updated:** [March 10, 2021, 12:26pm UTC](https://discourse.julialang.org/t/fft-planning-with-flags-fails-for-cuda/56870 "2021-03-10T12:26:30Z")

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Hey, I was trying to do a FFT plan for a CuArray. The following works: julia\> using CUDA, CUDA.CUFFT julia\> x = CUDA.rand(2, 2) 2×2 CuArray{Float32, 2}: 0.318697 0.144699 0.631969 0.433798 julia\> fft(x) 2×2 CuArr…

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## [Negative binomial layer](https://discourse.julialang.org/t/negative-binomial-layer/56804)

<div class="topic-metadata">

**Author:** [@lubo](https://discourse.julialang.org/u/lubo)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 10:45am UTC](https://discourse.julialang.org/t/negative-binomial-layer/56804 "2021-03-10T10:45:24Z")

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Hello, I am new to flux and I would appreciate help with implementing custom layer (or maybe custom activation?). Layer is like Dense layer, some inputs and outputs are exactly two neurons: first with NNlib.softplus ac…

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## [Analog of markevery in Plots.jl?](https://discourse.julialang.org/t/analog-of-markevery-in-plots-jl/10269)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 10\
**Last updated:** [March 9, 2021, 11:05pm UTC](https://discourse.julialang.org/t/analog-of-markevery-in-plots-jl/10269 "2021-03-09T23:05:26Z")

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Matplotlib had a nice feature, markevery=n, that, for a bivariate data set, allowed you to only plot every n-th point. This was quite useful if you had an abundance of data and wanted to reduce the graphical intensity o…

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## [Question on ODE system with inhomogeneous coefficients, parameters, code design](https://discourse.julialang.org/t/question-on-ode-system-with-inhomogeneous-coefficients-parameters-code-design/56849)

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**Author:** [@Ininterrompue](https://discourse.julialang.org/u/Ininterrompue)\
**Replies:** 5\
**Last updated:** [March 10, 2021, 6:08am UTC](https://discourse.julialang.org/t/question-on-ode-system-with-inhomogeneous-coefficients-parameters-code-design/56849 "2021-03-10T06:08:38Z")

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Hi, I have a question relating to code design. I’m using some ODE solvers to calculate a system of ODEs with time-varying coefficients which I am interested in. They take on the form F, G, and dG in the MWE and depend o…

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## [Householder routines reflector! and reflectorApply! in LinearAlgebra](https://discourse.julialang.org/t/householder-routines-reflector-and-reflectorapply-in-linearalgebra/56766)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 4\
**Last updated:** [March 10, 2021, 3:15am UTC](https://discourse.julialang.org/t/householder-routines-reflector-and-reflectorapply-in-linearalgebra/56766 "2021-03-10T03:15:33Z")

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Hello, I would like to use the routines reflector! and reflectorApply! of LinearAlgebra (julia/generic.jl at master · JuliaLang/julia · GitHub) to efficiently apply an Householder reflection to a vector a. The setup is…

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## [Please suggest improvements to the JuMP documentation](https://discourse.julialang.org/t/please-suggest-improvements-to-the-jump-documentation/55596)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 4\
**Last updated:** [March 9, 2021, 8:26pm UTC](https://discourse.julialang.org/t/please-suggest-improvements-to-the-jump-documentation/55596 "2021-03-09T20:26:37Z")

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Dear all, I have been busy making improvements to the JuMP documentation that will be available in the next release. (You can find the development version here: Introduction · JuMP) Highlights of the changes include int…

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## [KeyError: key not found](https://discourse.julialang.org/t/keyerror-key-not-found/56813)

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**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 1\
**Last updated:** [March 9, 2021, 5:03pm UTC](https://discourse.julialang.org/t/keyerror-key-not-found/56813 "2021-03-09T17:03:58Z")

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Hello everybody Because when I try to compile this part of the model it returns this error to me: KeyError: key 5 not found using JuMP, GLPK, GLPKMathProgInterface ModelD = Model(GLPK.Optimizer) t = 1:4 w = 1:2 l = …

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## [JuMP Mosek sparsity scaling](https://discourse.julialang.org/t/jump-mosek-sparsity-scaling/56731)

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**Author:** [@Philip\_Olhager](https://discourse.julialang.org/u/Philip_Olhager)\
**Replies:** 6\
**Last updated:** [March 9, 2021, 4:00pm UTC](https://discourse.julialang.org/t/jump-mosek-sparsity-scaling/56731 "2021-03-09T16:00:54Z")

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I’m trying to solve an SDP problem on the form \\begin{align} \\min \\hspace{0.5cm} & c^\\intercal x \\\\ \\text{s.t.} \\hspace{0.5cm} & A\_0 + \\sum A\_i x\_i \\succeq 0 \\end{align} with x being of size ~370 and the A matrices …

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## [Reverse proxy needed for Dash.jl app?](https://discourse.julialang.org/t/reverse-proxy-needed-for-dash-jl-app/56812)

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**Author:** [@Jakob](https://discourse.julialang.org/u/Jakob)\
**Replies:** 0\
**Last updated:** [March 9, 2021, 3:03pm UTC](https://discourse.julialang.org/t/reverse-proxy-needed-for-dash-jl-app/56812 "2021-03-09T15:03:09Z")

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I have a dashboard written in Dash.jl targeted at a relatively small audience. However, for the small Heroku dynos there’s just not enough memory and the larger ones get quite expensive so we were looking into hosting th…

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## [Fast GPU Kernels differentiable with Zygote](https://discourse.julialang.org/t/fast-gpu-kernels-differentiable-with-zygote/56756)

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**Author:** [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)\
**Replies:** 7\
**Last updated:** [March 9, 2021, 10:29am UTC](https://discourse.julialang.org/t/fast-gpu-kernels-differentiable-with-zygote/56756 "2021-03-09T10:29:15Z")

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Hey, so far I was using Tullio.jl to generate array based regularizers which are also (very) fast using Zygote.jl. So as an example a Total Variation regularizer: reg(x) = @tullio res = sqrt(abs2(x\[i, j\] - x\[i+1, j\]) …

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## [Is there a tool for 3D Delaunay and Voronoi tessellations?](https://discourse.julialang.org/t/is-there-a-tool-for-3d-delaunay-and-voronoi-tessellations/19503)

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**Author:** [@afas](https://discourse.julialang.org/u/afas)\
**Replies:** 12\
**Last updated:** [March 9, 2021, 7:47am UTC](https://discourse.julialang.org/t/is-there-a-tool-for-3d-delaunay-and-voronoi-tessellations/19503 "2021-03-09T07:47:44Z")

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I am currently migrating all my research software to Julia, and so far I am very pleased with the experience and the relative easiness in transporting code. I have, however, reached a bottleneck cause I can’t seem to be…

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## [Anyone has implemented Kernel SVD in this ICLR 2019 paper?](https://discourse.julialang.org/t/anyone-has-implemented-kernel-svd-in-this-iclr-2019-paper/56780)

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**Author:** [@Lian\_Yunlong](https://discourse.julialang.org/u/Lian_Yunlong)\
**Replies:** 0\
**Last updated:** [March 9, 2021, 2:52am UTC](https://discourse.julialang.org/t/anyone-has-implemented-kernel-svd-in-this-iclr-2019-paper/56780 "2021-03-09T02:52:15Z")

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Hello experts, recently I am trying out Flux.jl to initiate a research project on ML. I quickly ran into the issue of network compression and knowledge distillation. I have a background in physics and I have heard about…

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## [The need of (i)fftshift's to compute a PDE using Fourier Transform](https://discourse.julialang.org/t/the-need-of-i-fftshifts-to-compute-a-pde-using-fourier-transform/56587)

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**Author:** [@tiago](https://discourse.julialang.org/u/tiago)\
**Replies:** 12\
**Last updated:** [March 8, 2021, 8:54pm UTC](https://discourse.julialang.org/t/the-need-of-i-fftshifts-to-compute-a-pde-using-fourier-transform/56587 "2021-03-08T20:54:50Z")

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Hello, I’m currently writing an algorithm to solve a specific kind of PDE, via Fourier Transform. In the several examples that I saw, the general idea is to transform everything to the frequency domain using an fft, do…

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## [Grouping for color or markers in CairoMakie](https://discourse.julialang.org/t/grouping-for-color-or-markers-in-cairomakie/56728)

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**Author:** [@vjd](https://discourse.julialang.org/u/vjd)\
**Replies:** 6\
**Last updated:** [March 8, 2021, 2:52pm UTC](https://discourse.julialang.org/t/grouping-for-color-or-markers-in-cairomakie/56728 "2021-03-08T14:52:43Z")

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is there a way to groupby a dataframe column passed into color or marker such that each group gets a unique element? or does this have to be done as different scatter! calls for each group ccf = DataFrame(a = 1:4, …

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## [Dependencies when doing distributed](https://discourse.julialang.org/t/dependencies-when-doing-distributed/56736)

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**Author:** [@threadedblue](https://discourse.julialang.org/u/threadedblue)\
**Replies:** 0\
**Last updated:** [March 8, 2021, 2:41pm UTC](https://discourse.julialang.org/t/dependencies-when-doing-distributed/56736 "2021-03-08T14:41:09Z")

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I have a line of code like this: @everywhere include("encounters.jl") The file in question, encounters.jl has in it a line using AAUtils The module AAUtils is installed both locally and remotely. Q: From where is AA…

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## [Implementing SQLite / Spatialite driver](https://discourse.julialang.org/t/implementing-sqlite-spatialite-driver/55840)

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**Author:** [@maxfreu](https://discourse.julialang.org/u/maxfreu)\
**Replies:** 13\
**Last updated:** [March 8, 2021, 1:49pm UTC](https://discourse.julialang.org/t/implementing-sqlite-spatialite-driver/55840 "2021-03-08T13:49:43Z")

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Hi! I’m sick of the mess shapefiles create and it itches me to write a package for reading geometries from sqlite files (they proved to be rather small and fast last time I tested). Given the simplicity of the WKB format…

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## [Register a route which takes query parameters and extract those parameters to do the business logic](https://discourse.julialang.org/t/register-a-route-which-takes-query-parameters-and-extract-those-parameters-to-do-the-business-logic/56730)

<div class="topic-metadata">

**Author:** [@ispandey81](https://discourse.julialang.org/u/ispandey81)\
**Replies:** 0\
**Last updated:** [March 8, 2021, 1:06pm UTC](https://discourse.julialang.org/t/register-a-route-which-takes-query-parameters-and-extract-those-parameters-to-do-the-business-logic/56730 "2021-03-08T13:06:49Z")

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I am trying to register a route using HTTP.jl which takes a query parameter and extract that query parameter using HTTP.URIs.queryparams but cant’ get it to work. Any help appreciated. Sample code below. Want to invoke …

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## [AlgebraOfGraphics: how to add xlabel and ylabel](https://discourse.julialang.org/t/algebraofgraphics-how-to-add-xlabel-and-ylabel/56408)

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**Author:** [@phlavenk](https://discourse.julialang.org/u/phlavenk)\
**Replies:** 2\
**Last updated:** [March 8, 2021, 12:29pm UTC](https://discourse.julialang.org/t/algebraofgraphics-how-to-add-xlabel-and-ylabel/56408 "2021-03-08T12:29:52Z")

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I couldn’t find an example of how to add an x-axis label to the algebra flow. For example, in this simple plot, how would I add a “Number of cylinders” x label to both subfigures? using RDatasets: dataset using Algebra…

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