# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=479

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**Page:** 480

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## [DataFrames: removing columns with many missing values](https://discourse.julialang.org/t/dataframes-removing-columns-with-many-missing-values/29907)

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**Author:** [@johnbb](https://discourse.julialang.org/u/johnbb)\
**Replies:** 2\
**Last updated:** [October 14, 2019, 7:33pm UTC](https://discourse.julialang.org/t/dataframes-removing-columns-with-many-missing-values/29907 "2019-10-14T19:33:08Z")

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How can I remove columns with more than 10% missing data from a DataFrame? In R it would be x\[, colMeans(is.na(x)) \< 0.1\]. Thanks!

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## [Package for precision / recall?](https://discourse.julialang.org/t/package-for-precision-recall/29868)

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**Author:** [@mpratland](https://discourse.julialang.org/u/mpratland)\
**Replies:** 4\
**Last updated:** [October 14, 2019, 11:05am UTC](https://discourse.julialang.org/t/package-for-precision-recall/29868 "2019-10-14T11:05:26Z")

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I’m slowly moving all my personal projects and ML hacking over to Julia, so I’m trying to find substitutes for packages that I’m used to. On in particular I’m heavily dependent on is Python’s scikit-learn, and in particu…

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## [Kernel Error: kernel returns a value of type \`Union{}\`](https://discourse.julialang.org/t/kernel-error-kernel-returns-a-value-of-type-union/29885)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 3\
**Last updated:** [October 14, 2019, 6:52am UTC](https://discourse.julialang.org/t/kernel-error-kernel-returns-a-value-of-type-union/29885 "2019-10-14T06:52:37Z")

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I am trying to port my Julia code to be able to run with GPU support. I use LightGraphs package. My code and error message are as follows: cmin=0.5;cmax=0.9;N=1000;P=500;od=125;Pr=0.5;sigma=10;Pi=1.0; mutable struct Pa…

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## [Zygote gradient: problem with indexing constant arrays](https://discourse.julialang.org/t/zygote-gradient-problem-with-indexing-constant-arrays/29871)

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**Author:** [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Replies:** 1\
**Last updated:** [October 14, 2019, 12:28am UTC](https://discourse.julialang.org/t/zygote-gradient-problem-with-indexing-constant-arrays/29871 "2019-10-14T00:28:14Z")

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It looks super simple, function h(pars) my\_array = \[1.0, 2.0, 3.0\] indices = \[2,3,1\] # v = 0.0 for (c,i) in zip(pars,indices) v += c \* my\_array\[i\] end return v end h(\[1.0,2.0,3.0\]) # …

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## [Shape of input arrays for an LSTM in Flux.jl? julia 1.0](https://discourse.julialang.org/t/shape-of-input-arrays-for-an-lstm-in-flux-jl-julia-1-0/27418)

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**Author:** [@Simon\_Besnard](https://discourse.julialang.org/u/Simon_Besnard)\
**Replies:** 1\
**Last updated:** [October 13, 2019, 5:39pm UTC](https://discourse.julialang.org/t/shape-of-input-arrays-for-an-lstm-in-flux-jl-julia-1-0/27418 "2019-10-13T17:39:34Z")

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I am currently trying to implement an LSTM model for a regression exercise using the flux.jl library. Although it is rather straightforward to build-up the model, I have rather some issues in understanding the right shap…

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## [Serious group-by performance issue with Query.jl](https://discourse.julialang.org/t/serious-group-by-performance-issue-with-query-jl/29070)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 26\
**Last updated:** [October 13, 2019, 5:34am UTC](https://discourse.julialang.org/t/serious-group-by-performance-issue-with-query-jl/29070 "2019-10-13T05:34:41Z")

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Wanted to raise a performance issue at Query.jl but got directed here. I think Query.jl group-by is really inefficient and that’s why I never warmed to it. I use FileIO.jl but never Query.jl due to performance issues. E.…

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## [Plots.jl: add 2d histogram with logarithmic bin colors](https://discourse.julialang.org/t/plots-jl-add-2d-histogram-with-logarithmic-bin-colors/29802)

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**Author:** [@Sh4pe](https://discourse.julialang.org/u/Sh4pe)\
**Replies:** 0\
**Last updated:** [October 12, 2019, 12:22am UTC](https://discourse.julialang.org/t/plots-jl-add-2d-histogram-with-logarithmic-bin-colors/29802 "2019-10-12T00:22:43Z")

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I want to use 2d histograms in Plots.jl, especially with the GR backend, that have logarithmic bin colors (log10). This appears not to be possible at the moment (or is it?). So I’ve started the very short draft PR #2208 …

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## [Repeated measures 2 way ANOVA](https://discourse.julialang.org/t/repeated-measures-2-way-anova/375)

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**Author:** [@grero](https://discourse.julialang.org/u/grero)\
**Replies:** 4\
**Last updated:** [October 11, 2019, 3:02pm UTC](https://discourse.julialang.org/t/repeated-measures-2-way-anova/375 "2019-10-11T15:02:23Z")

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Hi group, I was wondering if anyone has julia code that can do repeated measures 2 way ANOVA? In the past, I’ve used the GLM package to do 2 way ANOVA, but it’s not clear to me how I would approach a repeated measures d…

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## [Write a GPU/CPU agnostic package with Flux](https://discourse.julialang.org/t/write-a-gpu-cpu-agnostic-package-with-flux/29734)

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**Author:** [@jonathan-laurent](https://discourse.julialang.org/u/jonathan-laurent)\
**Replies:** 5\
**Last updated:** [October 11, 2019, 1:34pm UTC](https://discourse.julialang.org/t/write-a-gpu-cpu-agnostic-package-with-flux/29734 "2019-10-11T13:34:56Z")

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I am currently developing a Julia package based on Flux (namely an implementation of Deepmind’s AlphaZero algorithm) and I am looking for the best way to make it accessible to people with and without a GPU. Ideally, ena…

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## [\[ANN\] SatelliteToolbox v0.6.3](https://discourse.julialang.org/t/ann-satellitetoolbox-v0-6-3/29760)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 0\
**Last updated:** [October 11, 2019, 2:07am UTC](https://discourse.julialang.org/t/ann-satellitetoolbox-v0-6-3/29760 "2019-10-11T02:07:35Z")

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Hi! I have just tagged the v0.6.3 of SatelliteToolbox.jl (it should be accepted soon, the PR can be seen here). This is a very interesting release. The modifications were: A bug in eclipse time computation was fixed. T…

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## [ERROR: \[Turing\] MH doesn't support vectorizing assume statement](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646)

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**Author:** [@jdhooghe](https://discourse.julialang.org/u/jdhooghe)\
**Replies:** 4\
**Last updated:** [October 9, 2019, 2:57pm UTC](https://discourse.julialang.org/t/error-turing-mh-doesnt-support-vectorizing-assume-statement/29646 "2019-10-09T14:57:18Z")

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Hello again. I am using Turing to re-create Facebook’s Prophet trend model. My model is: @model Trend(Years, y) = begin NumberOfChangepoints ~ DiscreteUniform(1, 5) s = collect(range(Years\[1\], length=1+NumberO…

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## [Modelling DFJ elminations constraints](https://discourse.julialang.org/t/modelling-dfj-elminations-constraints/29670)

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**Author:** [@Miguel\_Goncalves](https://discourse.julialang.org/u/Miguel_Goncalves)\
**Replies:** 2\
**Last updated:** [October 9, 2019, 1:41pm UTC](https://discourse.julialang.org/t/modelling-dfj-elminations-constraints/29670 "2019-10-09T13:41:27Z")

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Hi, everyone. I am new in this world of programming, specially in Julia, and i have found some trouble to ‘declare’ the subtour elimination from DFJ problems in Travelling Salesman Problem (TSP). Constrait: How can …

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## [Control points from a B-Spline](https://discourse.julialang.org/t/control-points-from-a-b-spline/29674)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 14\
**Last updated:** [October 9, 2019, 11:25am UTC](https://discourse.julialang.org/t/control-points-from-a-b-spline/29674 "2019-10-09T11:25:13Z")

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Is there any way I can retrieve the control points/polygon from a B-Spline (calculated from Dierckx.jl or Interpolations.jl)? Control points as described here and shown as the black polygon here: For instance, in the…

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## [Why isn't keys defined on SparseAxisArray?](https://discourse.julialang.org/t/why-isnt-keys-defined-on-sparseaxisarray/29667)

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**Author:** [@dourouc05](https://discourse.julialang.org/u/dourouc05)\
**Replies:** 4\
**Last updated:** [October 9, 2019, 9:26am UTC](https://discourse.julialang.org/t/why-isnt-keys-defined-on-sparseaxisarray/29667 "2019-10-09T09:26:19Z")

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In my code, I mostly use SparseAxisArray as an equivalent for dictionaries, except that it’s returned by JuMP. Thus, I’m trying to use keys on a SparseAxisArray, but it’s not behaving as expected, returning a DenseAxisAr…

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## [Hierarchical or multi-index for data frames](https://discourse.julialang.org/t/hierarchical-or-multi-index-for-data-frames/17076)

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**Author:** [@MatthiasKauer](https://discourse.julialang.org/u/MatthiasKauer)\
**Replies:** 10\
**Last updated:** [October 9, 2019, 8:23am UTC](https://discourse.julialang.org/t/hierarchical-or-multi-index-for-data-frames/17076 "2019-10-09T08:23:06Z")

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Hi, I’ve been looking around for data frame implementations. I found that GitHub - JuliaData/DataFrames.jl: In-memory tabular data in Julia does not support a hierarchical or multi-index approach. For clarification, I’…

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## [\[JuMP + Gurobi Bug?\] value of variable in solved model changes after deleting another variable](https://discourse.julialang.org/t/jump-gurobi-bug-value-of-variable-in-solved-model-changes-after-deleting-another-variable/29619)

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**Author:** [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Replies:** 7\
**Last updated:** [October 8, 2019, 10:54pm UTC](https://discourse.julialang.org/t/jump-gurobi-bug-value-of-variable-in-solved-model-changes-after-deleting-another-variable/29619 "2019-10-08T22:54:39Z")

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\> using JuMP, Gurobi \> model = Model(with\_optimizer(Gurobi.Optimizer)); \> @variable(model, x\[1:3\], Bin); \> @constraint(model, sum(all\_variables(model)) \<= 2); \> @objective(model, Max, sum(model\[:x\] .\* \[10, 5, 2\])); \> opt…

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## [Unable to save simple FLUX model with BSON](https://discourse.julialang.org/t/unable-to-save-simple-flux-model-with-bson/29628)

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**Author:** [@rio](https://discourse.julialang.org/u/rio)\
**Replies:** 2\
**Last updated:** [October 8, 2019, 4:40pm UTC](https://discourse.julialang.org/t/unable-to-save-simple-flux-model-with-bson/29628 "2019-10-08T16:40:10Z")

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Hi, When I try to save a simple FLUX model like using Flux, BSON model = Chain( Conv((3, 3), 1=\>16, pad=(1,1), relu), MaxPool((2,2)), Conv((3, 3), 16=\>32, pad=(1,1), relu), MaxPool((2,2)), Conv((3,…

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## [Ignore consecutive whitespaces with CSV.read(...)](https://discourse.julialang.org/t/ignore-consecutive-whitespaces-with-csv-read/11304)

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**Author:** [@e3c6](https://discourse.julialang.org/u/e3c6)\
**Replies:** 18\
**Last updated:** [October 8, 2019, 4:34pm UTC](https://discourse.julialang.org/t/ignore-consecutive-whitespaces-with-csv-read/11304 "2019-10-08T16:34:02Z")

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I am reading a file with CSV.read(...) that contains many consecutive spaces between columns because the colmuns are padded. I passed the keyword argument delim=' ', but it thinks that every space counts as a new column…

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## [Bioinitio Project?](https://discourse.julialang.org/t/bioinitio-project/29166)

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**Author:** [@kevbonham](https://discourse.julialang.org/u/kevbonham)\
**Replies:** 1\
**Last updated:** [October 8, 2019, 3:40pm UTC](https://discourse.julialang.org/t/bioinitio-project/29166 "2019-10-08T15:40:41Z")

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I just came across https://github.com/bionitio-team/bionitio, which provides templates for bioinformatics command line tools. I was thinking it might be good to submit something in julia as a sort of advertisement. I do…

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## [OpenCV on windows](https://discourse.julialang.org/t/opencv-on-windows/20499)

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**Author:** [@phlavenk](https://discourse.julialang.org/u/phlavenk)\
**Replies:** 6\
**Last updated:** [October 8, 2019, 3:28pm UTC](https://discourse.julialang.org/t/opencv-on-windows/20499 "2019-10-08T15:28:41Z")

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I’d like to ask what is the status and recommended approach for using OpenCV on windows. The OpenCV.jl uses CXX.jl for wrapping the C++ library and as such it is not really an option on Windows - the CXX package on wind…

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## [Modifying hotstart of a variable](https://discourse.julialang.org/t/modifying-hotstart-of-a-variable/29609)

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**Author:** [@gobs](https://discourse.julialang.org/u/gobs)\
**Replies:** 1\
**Last updated:** [October 7, 2019, 6:22pm UTC](https://discourse.julialang.org/t/modifying-hotstart-of-a-variable/29609 "2019-10-07T18:22:48Z")

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I would like to modify the hot start of a variable. I’ve given an minimum working example below: using JuMP, Gurobi, Ipopt m = Model(with\_optimizer(Ipopt.Optimizer)) @variable(m, x, start = 0) # hot start @constraint(m…

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## [JuMP 0.19 installed by default](https://discourse.julialang.org/t/jump-0-19-installed-by-default/29588)

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**Author:** [@leclere](https://discourse.julialang.org/u/leclere)\
**Replies:** 6\
**Last updated:** [October 7, 2019, 5:12pm UTC](https://discourse.julialang.org/t/jump-0-19-installed-by-default/29588 "2019-10-07T17:12:14Z")

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Hello, setting up my julia environnement from a Jupyter notebook (Julia 1.0.2) I get JuMP 0.19 when using Pkg.add(“JuMP”) while 0.20 is presented as stable and compatible with Julia 1.0. Can someone tell me if it is …

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## [DBSCAN using Hamming Distance Metric](https://discourse.julialang.org/t/dbscan-using-hamming-distance-metric/29606)

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**Author:** [@Mohamed\_Ismail](https://discourse.julialang.org/u/Mohamed_Ismail)\
**Replies:** 0\
**Last updated:** [October 7, 2019, 4:49pm UTC](https://discourse.julialang.org/t/dbscan-using-hamming-distance-metric/29606 "2019-10-07T16:49:50Z")

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I would like to use Clustering.DBSCAN and specify my own distance metric. Specifically, I want to use Hamming distance. The current DBSCAN interfaces do not seem to provide such option? Is there a workaround for this? …

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## [Plotting derived variables](https://discourse.julialang.org/t/plotting-derived-variables/29556)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 2\
**Last updated:** [October 6, 2019, 4:30pm UTC](https://discourse.julialang.org/t/plotting-derived-variables/29556 "2019-10-06T16:30:30Z")

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Hi, I am writing a function to read data from our simulation code output and plot with PyPlot. The data itself is mostly stored as an array with the 1st dimension as variable index and the rest as spatial indexes (1:nI,…

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## [Genie file management](https://discourse.julialang.org/t/genie-file-management/29537)

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**Author:** [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Replies:** 1\
**Last updated:** [October 6, 2019, 12:23am UTC](https://discourse.julialang.org/t/genie-file-management/29537 "2019-10-06T00:23:18Z")

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I am trying to add an app to my static html website using Genie. How can I manage my html template/style files and their path? For example, in my layout file in app.jl.html, there is a style.css that should be called. …

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## [Parallel Postprocessing](https://discourse.julialang.org/t/parallel-postprocessing/29487)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 10\
**Last updated:** [October 5, 2019, 7:00pm UTC](https://discourse.julialang.org/t/parallel-postprocessing/29487 "2019-10-05T19:00:21Z")

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Hi everyone, I am using Julia PyPlot to do postprocessing for simulation data. Here is the sample script for my parallel work: using Distributed @everywhere using PyCall @everywhere matplotlib = pyimport("matplotlib") …

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## [Interactive plotting from the REPL?](https://discourse.julialang.org/t/interactive-plotting-from-the-repl/29410)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 8\
**Last updated:** [October 5, 2019, 1:10am UTC](https://discourse.julialang.org/t/interactive-plotting-from-the-repl/29410 "2019-10-05T01:10:23Z")

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Goal is to do some interactive plotting from the REPL on linux (not using an Atom or Jupyter web browser) Previously I made the Fatou.jl package and I would like to make an interactive plot inspired by the repo: Ha…

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## [Plots.jl twinx question](https://discourse.julialang.org/t/plots-jl-twinx-question/29496)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 0\
**Last updated:** [October 4, 2019, 5:03pm UTC](https://discourse.julialang.org/t/plots-jl-twinx-question/29496 "2019-10-04T17:03:03Z")

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I have two questions about the twinx tool in Plots.jl: Is there a way to have a single legend that includes the labels for both sets? How do I assign a different ylabel to the right axes from the left axes?

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## [Distributed parallelism within packages/applications](https://discourse.julialang.org/t/distributed-parallelism-within-packages-applications/14320)

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**Author:** [@SebastianM-C](https://discourse.julialang.org/u/SebastianM-C)\
**Replies:** 15\
**Last updated:** [October 4, 2019, 2:30pm UTC](https://discourse.julialang.org/t/distributed-parallelism-within-packages-applications/14320 "2019-10-04T14:30:59Z")

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How can I use parallelism (on multiple processes) in a julia application/package? I have an application (in the Pkg3 sense that is not a package) in which I use pmap. I tried to load the package with using ParallelTest …

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## [How to add a constraint in a JuMP model using the obj function of another JuMP model](https://discourse.julialang.org/t/how-to-add-a-constraint-in-a-jump-model-using-the-obj-function-of-another-jump-model/29432)

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**Author:** [@Mahbubar06](https://discourse.julialang.org/u/Mahbubar06)\
**Replies:** 8\
**Last updated:** [October 3, 2019, 10:10pm UTC](https://discourse.julialang.org/t/how-to-add-a-constraint-in-a-jump-model-using-the-obj-function-of-another-jump-model/29432 "2019-10-03T22:10:33Z")

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Hello, I have the following JuMP model: using JuMP using MathProgBase using Ipopt model=Model(solver=IpoptSolver()) @variable(model, -100 \<= x\[1:5\] \<=100) @constraint(model, sum(x\[i\] for i in 1:5) \<= 50) @NLconstraint(…

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