# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=418

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**Page:** 419

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## [Exploring a model?](https://discourse.julialang.org/t/exploring-a-model/47472)

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**Author:** [@amca01](https://discourse.julialang.org/u/amca01)\
**Replies:** 5\
**Last updated:** [October 2, 2020, 4:37am UTC](https://discourse.julialang.org/t/exploring-a-model/47472 "2020-10-02T04:37:21Z")

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I have been investigating JuMP (with optimizers CBC, CLP, and GLPK) for linear models. I can obtain the values of the decision variables, the optimum of the objective function, the shadow prices of the binding constrain…

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## [No changes with Flux NN regression training](https://discourse.julialang.org/t/no-changes-with-flux-nn-regression-training/47490)

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**Author:** [@dmoored4](https://discourse.julialang.org/u/dmoored4)\
**Replies:** 2\
**Last updated:** [October 2, 2020, 3:03am UTC](https://discourse.julialang.org/t/no-changes-with-flux-nn-regression-training/47490 "2020-10-02T03:03:40Z")

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Problem Description Hi all, I’m having trouble using Flux to learn a non-linear function of two independent variables, x1 and x2. Everything is running, but I have a feeling that the parameters aren’t actually being upda…

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## [BUG Plots; pgfplotsx using twinx() ofsets the dates](https://discourse.julialang.org/t/bug-plots-pgfplotsx-using-twinx-ofsets-the-dates/47580)

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**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 2\
**Last updated:** [October 1, 2020, 8:32pm UTC](https://discourse.julialang.org/t/bug-plots-pgfplotsx-using-twinx-ofsets-the-dates/47580 "2020-10-01T20:32:57Z")

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Hi, I am using Plots;pgfplotsx() and the twinx() functionality and I want to report a bug that the dates are offset the dates as it can be seen in the figure. It will be great if this bug can be fixt. DateTick=cl…

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## [WAIC, or LOO etc in Turing?](https://discourse.julialang.org/t/waic-or-loo-etc-in-turing/30873)

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**Author:** [@aammd](https://discourse.julialang.org/u/aammd)\
**Replies:** 11\
**Last updated:** [October 1, 2020, 8:16pm UTC](https://discourse.julialang.org/t/waic-or-loo-etc-in-turing/30873 "2020-10-01T20:16:19Z")

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Hello everyone, I was wondering if any of the popular model selection criteria have been implemented in Turing? for example WAIC or LOO, etc? I am surprised that I can’t find mention of these in this forum or in the doc…

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## [Package for cell (morphological) profiling](https://discourse.julialang.org/t/package-for-cell-morphological-profiling/47500)

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**Author:** [@koalive](https://discourse.julialang.org/u/koalive)\
**Replies:** 3\
**Last updated:** [October 1, 2020, 5:34pm UTC](https://discourse.julialang.org/t/package-for-cell-morphological-profiling/47500 "2020-10-01T17:34:09Z")

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Hi there. I am currently working on a package compiling useful tools and structures for handling morphological profiles: https://github.com/menchelab/RMP.jl Concretely, part of my research work involves High Content S…

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## [Choosing the "best" sampler](https://discourse.julialang.org/t/choosing-the-best-sampler/47605)

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**Author:** [@mcql](https://discourse.julialang.org/u/mcql)\
**Replies:** 1\
**Last updated:** [October 1, 2020, 4:50pm UTC](https://discourse.julialang.org/t/choosing-the-best-sampler/47605 "2020-10-01T16:50:01Z")

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Hello, I would like to know how shoud I choose the sampler given a model (using the Turing framework). I haven’t found information in the official guide. Could you suggest me something to read about that related to th…

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## [Help for basic usage of @distributed for](https://discourse.julialang.org/t/help-for-basic-usage-of-distributed-for/31666)

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**Author:** [@Massimiliano\_Comin](https://discourse.julialang.org/u/Massimiliano_Comin)\
**Replies:** 1\
**Last updated:** [October 1, 2020, 9:27am UTC](https://discourse.julialang.org/t/help-for-basic-usage-of-distributed-for/31666 "2020-10-01T09:27:12Z")

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Hello, I have a computation that I want to perform several times for several realizations of disorder. For this I wrote a serial script doing only one computation, and a separate script that calls it and distributes the…

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## [How to get more info on w ∈ workers()](https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290)

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**Author:** [@healyp](https://discourse.julialang.org/u/healyp)\
**Replies:** 1\
**Last updated:** [October 1, 2020, 9:20am UTC](https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290 "2020-10-01T09:20:39Z")

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I’m getting the following error From worker 30: ErrorException("Process(30) - Invalid connection credentials sent by remote.")CapturedException(ErrorException("Process(30) - Invalid connection credentials sent by remote…

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## [Problems copying data on the GPU](https://discourse.julialang.org/t/problems-copying-data-on-the-gpu/47518)

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**Author:** [@bmit](https://discourse.julialang.org/u/bmit)\
**Replies:** 8\
**Last updated:** [October 1, 2020, 6:22am UTC](https://discourse.julialang.org/t/problems-copying-data-on-the-gpu/47518 "2020-10-01T06:22:24Z")

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I’m having trouble with a basic copy operation on the GPU. My goal is to copy a chosen subset of data from an N-D array into a vector. My following two attempts have failed. using CUDA CUDA.allowscalar(false) a=CUDA.ran…

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## [Flux model with categorical and continuous covariates/features](https://discourse.julialang.org/t/flux-model-with-categorical-and-continuous-covariates-features/47556)

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**Author:** [@johnbb](https://discourse.julialang.org/u/johnbb)\
**Replies:** 0\
**Last updated:** [September 30, 2020, 10:49pm UTC](https://discourse.julialang.org/t/flux-model-with-categorical-and-continuous-covariates-features/47556 "2020-09-30T22:49:53Z")

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Using Flux, I would like to train a regression model with both continuous and categorical features. Since the categorical variable(s) may have a many levels, I would prefer to map these into a few new continuous variable…

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## [Vectorizing observations from multivariate distribution in Turing](https://discourse.julialang.org/t/vectorizing-observations-from-multivariate-distribution-in-turing/47436)

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**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 1\
**Last updated:** [September 30, 2020, 9:06pm UTC](https://discourse.julialang.org/t/vectorizing-observations-from-multivariate-distribution-in-turing/47436 "2020-09-30T21:06:31Z")

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I have a model where the data are drawn from multinomial distributions. The parameters of those distributions (number of draws and probabilities) are different at each data point. MWE below: ndata = 100 k = 5 n = 10 p…

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## [Ipopt and external function](https://discourse.julialang.org/t/ipopt-and-external-function/47496)

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**Author:** [@danicaratelli](https://discourse.julialang.org/u/danicaratelli)\
**Replies:** 11\
**Last updated:** [September 30, 2020, 6:40pm UTC](https://discourse.julialang.org/t/ipopt-and-external-function/47496 "2020-09-30T18:40:17Z")

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I am trying to solve a non-linear function using JuMP. From what I saw, I have to use Ipopt and, as Nonlinear Modeling · JuMP says, I cannot directly include the function in the NLobjective. To get around this I define a…

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## [Finding a vector which has the sum of the indices which are prime numbers](https://discourse.julialang.org/t/finding-a-vector-which-has-the-sum-of-the-indices-which-are-prime-numbers/47492)

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**Author:** [@julianoob](https://discourse.julialang.org/u/julianoob)\
**Replies:** 7\
**Last updated:** [September 30, 2020, 6:28pm UTC](https://discourse.julialang.org/t/finding-a-vector-which-has-the-sum-of-the-indices-which-are-prime-numbers/47492 "2020-09-30T18:28:56Z")

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For example a=\[1 2 3; 4 5 6; 7 8 9\] indices are ((1,1) ,(1,2) , (1,3); (2,1),(2,2),(2,3); (3,1),(3,2),(3,3)) and the prime number of these sums are 2,3,5 which should be in the vector s. Is there any function in julia wh…

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## [Most efficient way of computing B'\* inv(A)\* B for A large](https://discourse.julialang.org/t/most-efficient-way-of-computing-b-inv-a-b-for-a-large/47513)

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**Author:** [@Joris\_Pinkse](https://discourse.julialang.org/u/Joris_Pinkse)\
**Replies:** 30\
**Last updated:** [September 30, 2020, 4:19pm UTC](https://discourse.julialang.org/t/most-efficient-way-of-computing-b-inv-a-b-for-a-large/47513 "2020-09-30T16:19:04Z")

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I have a positive definite high-dimensional matrix A and wish to compute B’ \* inv(A) \* B where the result is low-dimensional. What is the fastest way of accomplishing this for generic B?

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## [GraphRecipes (or equivalent) for this series of plots](https://discourse.julialang.org/t/graphrecipes-or-equivalent-for-this-series-of-plots/47544)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 0\
**Last updated:** [September 30, 2020, 4:09pm UTC](https://discourse.julialang.org/t/graphrecipes-or-equivalent-for-this-series-of-plots/47544 "2020-09-30T16:09:44Z")

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I have a directed graph in LightGraphs and I want to produce a series of plots each with the same circular layout but highlighting different subsets of edges, with highlighting on the nodes:

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## [Returning a value calculated inside the ODE function](https://discourse.julialang.org/t/returning-a-value-calculated-inside-the-ode-function/47529)

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**Author:** [@fkrauer](https://discourse.julialang.org/u/fkrauer)\
**Replies:** 1\
**Last updated:** [September 30, 2020, 12:52pm UTC](https://discourse.julialang.org/t/returning-a-value-calculated-inside-the-ode-function/47529 "2020-09-30T12:52:20Z")

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Hi I am using julia via R to simulate compartmental epidemic ODE models. Is there a way to return a value that is calculated inside the ODE function for every step of the integration? So far it only returns the states. …

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## [LASSO.jl, GLMNet.jl - hyperparameters](https://discourse.julialang.org/t/lasso-jl-glmnet-jl-hyperparameters/28799)

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**Author:** [@versipellis](https://discourse.julialang.org/u/versipellis)\
**Replies:** 6\
**Last updated:** [September 30, 2020, 9:35am UTC](https://discourse.julialang.org/t/lasso-jl-glmnet-jl-hyperparameters/28799 "2020-09-30T09:35:34Z")

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I’m not seeing any documentation for such, but in LASSO.jl and GLMNet.jl, I’m looking to do the following: Specify a validation set to train hyperparameters on, rather than just using cross-validation. I know CV is bet…

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## [Adding textures to rectangles using Makie](https://discourse.julialang.org/t/adding-textures-to-rectangles-using-makie/11465)

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**Author:** [@fabiangans](https://discourse.julialang.org/u/fabiangans)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 8:57am UTC](https://discourse.julialang.org/t/adding-textures-to-rectangles-using-makie/11465 "2020-09-30T08:57:49Z")

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I want to create a number of textured (rotated) rectangles where the 3D corner coordinates are given in a single plot using Makie.jl or GLVizualize. I want a plot similar to this example where the earth image is plotted …

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## [Cant create dataframe](https://discourse.julialang.org/t/cant-create-dataframe/47502)

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**Author:** [@andresmorago](https://discourse.julialang.org/u/andresmorago)\
**Replies:** 16\
**Last updated:** [September 29, 2020, 10:00pm UTC](https://discourse.julialang.org/t/cant-create-dataframe/47502 "2020-09-29T22:00:16Z")

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Hello guys. Newbie here I have this array getvalue.(W) 1-dimensional DenseAxisArray{Float64,1,…} with index sets: Dimension 1, 0:6 And data, a 7-element Array{Float64,1}: 80.0 65.0 65.0 65.0 65.0 65.0 65.0 …

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## [Implementing Crystal Graph CNN in Julia](https://discourse.julialang.org/t/implementing-crystal-graph-cnn-in-julia/33169)

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**Author:** [@rkurchin](https://discourse.julialang.org/u/rkurchin)\
**Replies:** 4\
**Last updated:** [September 29, 2020, 6:56pm UTC](https://discourse.julialang.org/t/implementing-crystal-graph-cnn-in-julia/33169 "2020-09-29T18:56:11Z")

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Hi everyone! I’d like to implement Crystal Graph Convolutional Neural Networks (CGCNNs) in Julia, in particular using the GeometricFlux package. CGCNN’s are a method in computational materials science for representing cr…

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## [Debugging with CUDA.jl](https://discourse.julialang.org/t/debugging-with-cuda-jl/47493)

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**Author:** [@bmit](https://discourse.julialang.org/u/bmit)\
**Replies:** 1\
**Last updated:** [September 29, 2020, 5:50pm UTC](https://discourse.julialang.org/t/debugging-with-cuda-jl/47493 "2020-09-29T17:50:09Z")

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Does Debugger.jl work with CUDA.jl? I haven’t had any luck and wasn’t sure if I was missing something or it’s not supposed to work. Here’s the simplest case I came up with: using CUDA using Debugger function test\_cuda\_d…

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## [What scaling applies to the irfft (inverse fast fourier transform - FFTW.jl package)](https://discourse.julialang.org/t/what-scaling-applies-to-the-irfft-inverse-fast-fourier-transform-fftw-jl-package/47476)

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**Author:** [@jleman](https://discourse.julialang.org/u/jleman)\
**Replies:** 4\
**Last updated:** [September 29, 2020, 5:28pm UTC](https://discourse.julialang.org/t/what-scaling-applies-to-the-irfft-inverse-fast-fourier-transform-fftw-jl-package/47476 "2020-09-29T17:28:37Z")

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I am trying to understand scaling of the irfft function of the FFTW.jl package. I have a function that defines a continuous frequency domain signal (in radians). The complex portion of the signal has odd symmetry and t…

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## [DiffEqFlux Autodifferentiating inside loss function](https://discourse.julialang.org/t/diffeqflux-autodifferentiating-inside-loss-function/47203)

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**Author:** [@Axlrsn](https://discourse.julialang.org/u/Axlrsn)\
**Replies:** 6\
**Last updated:** [September 29, 2020, 3:03pm UTC](https://discourse.julialang.org/t/diffeqflux-autodifferentiating-inside-loss-function/47203 "2020-09-29T15:03:25Z")

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Hello, I am new to Julia and especially the way Zygote works. For a project in physics informed machine learning I have a neural network NN(x) approximating a function f(x). I want to take the gradient of the neural net…

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## [GPLK vs Gurobi speed on simple MIPs](https://discourse.julialang.org/t/gplk-vs-gurobi-speed-on-simple-mips/47383)

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**Author:** [@adow031](https://discourse.julialang.org/u/adow031)\
**Replies:** 11\
**Last updated:** [September 29, 2020, 1:07pm UTC](https://discourse.julialang.org/t/gplk-vs-gurobi-speed-on-simple-mips/47383 "2020-09-29T13:07:21Z")

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I’m needing to solve a large number of simple MIPs in succession, and I’m finding that GPLK is 2.5 times faster than Gurobi (with presolve disabled; presolve slows Gurobi further). Is this normal? I know that for large/…

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## [Complex-valued functions with real arguments - ForwardDiff, JuliaDiff](https://discourse.julialang.org/t/complex-valued-functions-with-real-arguments-forwarddiff-juliadiff/27386)

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**Author:** [@marcvb97](https://discourse.julialang.org/u/marcvb97)\
**Replies:** 6\
**Last updated:** [September 28, 2020, 10:41pm UTC](https://discourse.julialang.org/t/complex-valued-functions-with-real-arguments-forwarddiff-juliadiff/27386 "2020-09-28T22:41:30Z")

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When executing the following code to apply ForwardDiff to a complex-valued function with real argument: using ForwardDiff f2(t::Real) = real( (cos(t) + 1im\*sin(t))^(1/2) ) t = pi/2 ForwardDiff.derivative(f2,t) I get th…

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## [Contour plot of separate, intersecting levels](https://discourse.julialang.org/t/contour-plot-of-separate-intersecting-levels/47400)

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**Author:** [@ric.cioffi](https://discourse.julialang.org/u/ric.cioffi)\
**Replies:** 6\
**Last updated:** [September 28, 2020, 7:47pm UTC](https://discourse.julialang.org/t/contour-plot-of-separate-intersecting-levels/47400 "2020-09-28T19:47:35Z")

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Problem Hi, I’m having a hard time figuring out how to do the following, though I’m sure there must be some “easy” solution that I just cannot find. I have a 3-dimensional array of booleans and I’d like to see the “cont…

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## [Extract field from the elements of a column in a DataFrame](https://discourse.julialang.org/t/extract-field-from-the-elements-of-a-column-in-a-dataframe/47405)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 3\
**Last updated:** [September 28, 2020, 4:58pm UTC](https://discourse.julialang.org/t/extract-field-from-the-elements-of-a-column-in-a-dataframe/47405 "2020-09-28T16:58:34Z")

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Let’s say I a have a DataFrame with a column :C1. The elements of the column are structs of the type struct MyStruct a::Float64 b::Float64 end How do I extract, for example, the field :a from the elements of th…

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## [(d::Int)(x::Int) = d + x?](https://discourse.julialang.org/t/d-int-x-int-d-x/47321)

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**Author:** [@bigdataman2015](https://discourse.julialang.org/u/bigdataman2015)\
**Replies:** 5\
**Last updated:** [September 28, 2020, 11:12am UTC](https://discourse.julialang.org/t/d-int-x-int-d-x/47321 "2020-09-28T11:12:12Z")

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julia\> (d::Int)(x::Int) = d + x # what does this mean ?

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## [Testing code that is executed when solve reaches non-optimal status](https://discourse.julialang.org/t/testing-code-that-is-executed-when-solve-reaches-non-optimal-status/47293)

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**Author:** [@vtjeng](https://discourse.julialang.org/u/vtjeng)\
**Replies:** 3\
**Last updated:** [September 27, 2020, 10:51pm UTC](https://discourse.julialang.org/t/testing-code-that-is-executed-when-solve-reaches-non-optimal-status/47293 "2020-09-27T22:51:50Z")

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I’m looking for advice on the best way to test code that is executed only when the termination status for optimization returns a status of MathOptInterface.TIME\_LIMIT. The first approach I tried was to construct models …

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## [How to do distributed multithreading?](https://discourse.julialang.org/t/how-to-do-distributed-multithreading/47373)

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**Author:** [@vkv](https://discourse.julialang.org/u/vkv)\
**Replies:** 1\
**Last updated:** [September 27, 2020, 10:30pm UTC](https://discourse.julialang.org/t/how-to-do-distributed-multithreading/47373 "2020-09-27T22:30:31Z")

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I’ve a function that uses multithreading to compute a function f with each thread value and stores the value as an array element. function multithread() num\_threads = 8 output = Array{Float64}(num\_thread…

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