# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?page=487

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

**Page:** 488

---

## [Metaprogramming with types](https://discourse.julialang.org/t/metaprogramming-with-types/27195)

<div class="topic-metadata">

**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 14\
**Last updated:** [August 9, 2019, 3:22am UTC](https://discourse.julialang.org/t/metaprogramming-with-types/27195 "2019-08-09T03:22:45Z")

</div>

I had been building my log-density function like this: julia\> sourceLogdensity(linReg1D) :(function ##logdensity#413(pars) @unpack (α, β, σ, x, y) = pars ℓ = 0.0 ℓ += logpdf(Cauchy(0, 10), α) ℓ +…

---

## [How to construct a video object for display by ImageView.imshow()](https://discourse.julialang.org/t/how-to-construct-a-video-object-for-display-by-imageview-imshow/27323)

<div class="topic-metadata">

**Author:** [@tgf314](https://discourse.julialang.org/u/tgf314)\
**Replies:** 1\
**Last updated:** [August 9, 2019, 12:00am UTC](https://discourse.julialang.org/t/how-to-construct-a-video-object-for-display-by-imageview-imshow/27323 "2019-08-09T00:00:26Z")

</div>

imshow() is described as being able to display a video. The example in the documentation is testimage(“mri”). The type of this object is: \`AxisArray{Gray{Normed{UInt8,8}},3,Array{Gray{Normed{UInt8,8}},3},Tuple{AxisArr…

---

## [Obtain and print IIS using Gurobi](https://discourse.julialang.org/t/obtain-and-print-iis-using-gurobi/27116)

<div class="topic-metadata">

**Author:** [@lgo](https://discourse.julialang.org/u/lgo)\
**Replies:** 2\
**Last updated:** [August 3, 2019, 6:21pm UTC](https://discourse.julialang.org/t/obtain-and-print-iis-using-gurobi/27116 "2019-08-03T18:21:15Z")

</div>

Hello, Gurobi has a function to obtain a Irreducible Inconsistent Subsystem (ISS), which refers to a subset of equations causing infeasibility. This obviously comes in very handy when debugging your problem. I succeede…

---

## [R session aborted when reading feather file from Julia](https://discourse.julialang.org/t/r-session-aborted-when-reading-feather-file-from-julia/25937)

<div class="topic-metadata">

**Author:** [@ElOceanografo](https://discourse.julialang.org/u/ElOceanografo)\
**Replies:** 3\
**Last updated:** [August 8, 2019, 7:30pm UTC](https://discourse.julialang.org/t/r-session-aborted-when-reading-feather-file-from-julia/25937 "2019-08-08T19:30:26Z")

</div>

I’m trying to output a DataFrame as a Feather file from a Julia script and then import it into R. When I try to load it, though, R crashes (RGui closes out immediately, RStudio gives me an “R session aborted: R encount…

---

## [Creating graphs from data](https://discourse.julialang.org/t/creating-graphs-from-data/27199)

<div class="topic-metadata">

**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 7\
**Last updated:** [August 7, 2019, 7:50pm UTC](https://discourse.julialang.org/t/creating-graphs-from-data/27199 "2019-08-07T19:50:01Z")

</div>

A common procedure in data science and mathematics is building graphs/networks from a large collection of data points. I am interested in the constructing the adjacency matrix for the k-nearest neighbor graph of a collec…

---

## [Memory allocation and SharedArrays](https://discourse.julialang.org/t/memory-allocation-and-sharedarrays/27272)

<div class="topic-metadata">

**Author:** [@HugoLhuillier](https://discourse.julialang.org/u/HugoLhuillier)\
**Replies:** 3\
**Last updated:** [August 7, 2019, 10:43pm UTC](https://discourse.julialang.org/t/memory-allocation-and-sharedarrays/27272 "2019-08-07T22:43:10Z")

</div>

Hi all, I am new to parallel computing and I had a question regarding memory allocation. Is it possible to update an array in place while doing parallel computing? I tried using SharedArrays and DistributedArrays witho…

---

## [How do you make zoomable inline plot with PyPlot.jl?](https://discourse.julialang.org/t/how-do-you-make-zoomable-inline-plot-with-pyplot-jl/12294)

<div class="topic-metadata">

**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 2\
**Last updated:** [August 7, 2019, 12:47pm UTC](https://discourse.julialang.org/t/how-do-you-make-zoomable-inline-plot-with-pyplot-jl/12294 "2019-08-07T12:47:43Z")

</div>

It seems, that according to PyPlot.jl documentation, you have only two options: You make the plots inline, but you can not interact with them, no zoom etc. You make the plots in separate GUI windows, then you gain acce…

---

## [Drawing on widgets defined in a layout produced from Glade](https://discourse.julialang.org/t/drawing-on-widgets-defined-in-a-layout-produced-from-glade/27197)

<div class="topic-metadata">

**Author:** [@mantzaris](https://discourse.julialang.org/u/mantzaris)\
**Replies:** 5\
**Last updated:** [August 7, 2019, 3:38am UTC](https://discourse.julialang.org/t/drawing-on-widgets-defined-in-a-layout-produced-from-glade/27197 "2019-08-07T03:38:37Z")

</div>

I can draw on canvases (created via Gtk.Canvas) which are are then pushed onto containers, and have their draw functions set to functions I have written (eg. canvasA.draw = drawFnA) and in that draw function use the some…

---

## [Using a macro to define two methods at once?](https://discourse.julialang.org/t/using-a-macro-to-define-two-methods-at-once/27239)

<div class="topic-metadata">

**Author:** [@longemen3000](https://discourse.julialang.org/u/longemen3000)\
**Replies:** 2\
**Last updated:** [August 7, 2019, 3:14am UTC](https://discourse.julialang.org/t/using-a-macro-to-define-two-methods-at-once/27239 "2019-08-07T03:14:26Z")

</div>

there is a way to define two methods of a function with a macro?, for example, a macro like this: f = @mymacro (2,3) that generates the following code: f(x) = 2\*x f(x,y) = 2\*x+3\*y the example is simple and what i’m l…

---

## [Gradient loop vs batch gradient speed](https://discourse.julialang.org/t/gradient-loop-vs-batch-gradient-speed/27209)

<div class="topic-metadata">

**Author:** [@CraftyVisage](https://discourse.julialang.org/u/CraftyVisage)\
**Replies:** 4\
**Last updated:** [August 7, 2019, 12:01am UTC](https://discourse.julialang.org/t/gradient-loop-vs-batch-gradient-speed/27209 "2019-08-07T00:01:36Z")

</div>

I am training a neural network using a manual custom gradient update. I have a loop that goes through every example and computes the gradient of the loss on that example. I then use that gradient in my custom update. Th…

---

## [Workaround for modifying coefficients in constraints in JuMP?](https://discourse.julialang.org/t/workaround-for-modifying-coefficients-in-constraints-in-jump/27123)

<div class="topic-metadata">

**Author:** [@torgo](https://discourse.julialang.org/u/torgo)\
**Replies:** 9\
**Last updated:** [August 6, 2019, 8:09pm UTC](https://discourse.julialang.org/t/workaround-for-modifying-coefficients-in-constraints-in-jump/27123 "2019-08-06T20:09:34Z")

</div>

In the 0.19 documentation on this page it says: Modifying a constant term Most often, modifications involve changing the “right-hand side” of a linear constraint. This presents a challenge for JuMP because it leads to …

---

## [JuliaCon 2019 talks](https://discourse.julialang.org/t/juliacon-2019-talks/26811)

<div class="topic-metadata">

**Author:** [@trappmartin](https://discourse.julialang.org/u/trappmartin)\
**Replies:** 4\
**Last updated:** [August 6, 2019, 7:36pm UTC](https://discourse.julialang.org/t/juliacon-2019-talks/26811 "2019-08-06T19:36:13Z")

</div>

Here are the links to the talks on probabilistic programming during JuliaCon 2019. JuliaCon 2019 | Turing: Probabalistic Programming in Julia | Cameron Pfiffer - YouTube JuliaCon 2019 | Gaussian Process Probabilistic P…

---

## [Difficulty building JuMP SparseAxisArrays for network problems](https://discourse.julialang.org/t/difficulty-building-jump-sparseaxisarrays-for-network-problems/27227)

<div class="topic-metadata">

**Author:** [@pulsipher](https://discourse.julialang.org/u/pulsipher)\
**Replies:** 1\
**Last updated:** [August 6, 2019, 4:51pm UTC](https://discourse.julialang.org/t/difficulty-building-jump-sparseaxisarrays-for-network-problems/27227 "2019-08-06T16:51:32Z")

</div>

I am trying to model a network flow problem via JuMP and I am having difficulty building the flow variables with the correct indexing using @variable. For example, let’s suppose I have a network with 2 flow variables x\_…

---

## [Trouble with nested summations in objective funtion](https://discourse.julialang.org/t/trouble-with-nested-summations-in-objective-funtion/27215)

<div class="topic-metadata">

**Author:** [@Natedogg373](https://discourse.julialang.org/u/Natedogg373)\
**Replies:** 3\
**Last updated:** [August 6, 2019, 1:22pm UTC](https://discourse.julialang.org/t/trouble-with-nested-summations-in-objective-funtion/27215 "2019-08-06T13:22:02Z")

</div>

Hello, I’m a beginner with julia and working on a MIP optimization problem and I’ve been having trouble finishing my objective. Below is the portion of the objective I have traced the error to. sum(sum(3\*t\[i,j,l\]+v1\[i…

---

## [How to see the output from DSP.Periodograms.periodogram?](https://discourse.julialang.org/t/how-to-see-the-output-from-dsp-periodograms-periodogram/26732)

<div class="topic-metadata">

**Author:** [@Andrzej\_Ceglowski](https://discourse.julialang.org/u/Andrzej_Ceglowski)\
**Replies:** 2\
**Last updated:** [August 6, 2019, 2:26am UTC](https://discourse.julialang.org/t/how-to-see-the-output-from-dsp-periodograms-periodogram/26732 "2019-08-06T02:26:23Z")

</div>

Thank you for taking the time to look at my rookie problem. I cannot find documentation on the periodogram type variable and consequently cannot access the results of DSP periodograms routine. Can you help? The steps/d…

---

## [How can I solve "no method matching Chains" in Turing - Julia](https://discourse.julialang.org/t/how-can-i-solve-no-method-matching-chains-in-turing-julia/27166)

<div class="topic-metadata">

**Author:** [@Manu\_Francis](https://discourse.julialang.org/u/Manu_Francis)\
**Replies:** 4\
**Last updated:** [August 6, 2019, 1:27am UTC](https://discourse.julialang.org/t/how-can-i-solve-no-method-matching-chains-in-turing-julia/27166 "2019-08-06T01:27:03Z")

</div>

Hi, I am trying to learn as a beginner of Julia and Turing and run the following program given in Turing tutorial. # Import libraries. using Turing, StatsPlots, Random # Set the true probability of heads in a coin. p\_…

---

## [Query.jl - Return all columns with @map](https://discourse.julialang.org/t/query-jl-return-all-columns-with-map/11717)

<div class="topic-metadata">

**Author:** [@joshualeond](https://discourse.julialang.org/u/joshualeond)\
**Replies:** 3\
**Last updated:** [August 5, 2019, 7:13pm UTC](https://discourse.julialang.org/t/query-jl-return-all-columns-with-map/11717 "2019-08-05T19:13:45Z")

</div>

Hey there, I recently watched @davidanthoff’s Queryverse tutorial and am giving Query.jl a go. I like the new pipe-able syntax as I’m a heavy user of dplyr. I see the @map macro would be similar to the select and mutate …

---

## [PGFPlotsX.jl - custom color cycler?](https://discourse.julialang.org/t/pgfplotsx-jl-custom-color-cycler/27178)

<div class="topic-metadata">

**Author:** [@tamasgal](https://discourse.julialang.org/u/tamasgal)\
**Replies:** 8\
**Last updated:** [August 5, 2019, 3:47pm UTC](https://discourse.julialang.org/t/pgfplotsx-jl-custom-color-cycler/27178 "2019-08-05T15:47:54Z")

</div>

I am trying to use a custom color cycler for all my plots in my thesis. In my LaTeX style document I defined some colours for testing, here is an example which I found on SO: \\usepackage{pgfplots} \\definecolor{blues1}{…

---

## [Start up costs when using remotecall\_fetch](https://discourse.julialang.org/t/start-up-costs-when-using-remotecall-fetch/27072)

<div class="topic-metadata">

**Author:** [@DanielAvilaGirardot](https://discourse.julialang.org/u/DanielAvilaGirardot)\
**Replies:** 2\
**Last updated:** [August 4, 2019, 2:21pm UTC](https://discourse.julialang.org/t/start-up-costs-when-using-remotecall-fetch/27072 "2019-08-04T14:21:51Z")

</div>

Hello, Is there a measure of the start up costs when using functions such as pmap or remotecall\_fetch?. By start up cost I mean the time elapsed from the instant in which the remotecall\_fetch command is called and the i…

---

## [Reusing variable in multiple parallel calls](https://discourse.julialang.org/t/reusing-variable-in-multiple-parallel-calls/23187)

<div class="topic-metadata">

**Author:** [@dsweber2](https://discourse.julialang.org/u/dsweber2)\
**Replies:** 5\
**Last updated:** [August 4, 2019, 11:48am UTC](https://discourse.julialang.org/t/reusing-variable-in-multiple-parallel-calls/23187 "2019-08-04T11:48:35Z")

</div>

I am going to be calling the same fft on several remote workers many times each. To get an additional speed improvement, I am aiming to use plan\_fft. But plan\_fft objects aren’t thread safe, so I can’t reuse the same pla…

---

## [Error with building NLexpression in JuMP 0.19.2](https://discourse.julialang.org/t/error-with-building-nlexpression-in-jump-0-19-2/26998)

<div class="topic-metadata">

**Author:** [@pulsipher](https://discourse.julialang.org/u/pulsipher)\
**Replies:** 4\
**Last updated:** [August 3, 2019, 10:23pm UTC](https://discourse.julialang.org/t/error-with-building-nlexpression-in-jump-0-19-2/26998 "2019-08-03T22:23:53Z")

</div>

I ran into this unexpected error when trying to build a nonlinear expression. julia\> mean\_vs = @NLexpression(model, \[i = 1:num\_buses\], sum(prod2.get(\[m-1, m-1\]) \* (vre\_coeffs\[i, m\]^2 + vim…

---

## [Multiple amount of summations in JuMP](https://discourse.julialang.org/t/multiple-amount-of-summations-in-jump/27083)

<div class="topic-metadata">

**Author:** [@newjuliauser](https://discourse.julialang.org/u/newjuliauser)\
**Replies:** 1\
**Last updated:** [August 3, 2019, 8:39am UTC](https://discourse.julialang.org/t/multiple-amount-of-summations-in-jump/27083 "2019-08-03T08:39:53Z")

</div>

Hello, I’m wondering If it is possible to pass a multi summation expression into setNLobjective. Currently I have a for loop to compute summation, but, I was wondering if it is possible to optimize with JuMP on this fron…

---

## [Reading Data Is Still Too Slow](https://discourse.julialang.org/t/reading-data-is-still-too-slow/17919)

<div class="topic-metadata">

**Author:** [@iwelch](https://discourse.julialang.org/u/iwelch)\
**Replies:** 35\
**Last updated:** [August 2, 2019, 10:49pm UTC](https://discourse.julialang.org/t/reading-data-is-still-too-slow/17919 "2019-08-02T22:49:41Z")

</div>

My crsp daily stock return data is a 6.4GB csv file. Compressed into csv.gz, it is about 1.7GB. (I posted a sample with my juliadb post, https://discourse.julialang.org/t/juliadb-getting-started-with-save-error/17891/4…

---

## [Instatiate a tracked array? or dynamically store slices of a tracked array? (Not sure what to call this)](https://discourse.julialang.org/t/instatiate-a-tracked-array-or-dynamically-store-slices-of-a-tracked-array-not-sure-what-to-call-this/27101)

<div class="topic-metadata">

**Author:** [@tue](https://discourse.julialang.org/u/tue)\
**Replies:** 6\
**Last updated:** [August 2, 2019, 7:30pm UTC](https://discourse.julialang.org/t/instatiate-a-tracked-array-or-dynamically-store-slices-of-a-tracked-array-not-sure-what-to-call-this/27101 "2019-08-02T19:30:34Z")

</div>

I have some code where I compute what essentially boils down to the following: di = zeros(n,knn) for i=1:n di\[i,:\] = d\[idx\[i\]\] end Now the problem is that d is a tracked array, and hence it cannot be put inside di …

---

## [Balanced Repeated Replication in Julia](https://discourse.julialang.org/t/balanced-repeated-replication-in-julia/27003)

<div class="topic-metadata">

**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 5\
**Last updated:** [August 2, 2019, 4:55pm UTC](https://discourse.julialang.org/t/balanced-repeated-replication-in-julia/27003 "2019-08-02T16:55:33Z")

</div>

Hi All, I am working with a public data source and I’m having trouble understanding how to compute replicate weights that are needed for calculating the standard errors for my estimates. The data source is here, if you’…

---

## [Solving a cplex model via JuMP and java](https://discourse.julialang.org/t/solving-a-cplex-model-via-jump-and-java/26646)

<div class="topic-metadata">

**Author:** [@healyp](https://discourse.julialang.org/u/healyp)\
**Replies:** 10\
**Last updated:** [August 2, 2019, 9:55am UTC](https://discourse.julialang.org/t/solving-a-cplex-model-via-jump-and-java/26646 "2019-08-02T09:55:24Z")

</div>

A colleague and I both implemented a model we have been working on, him using a java interface to cplex and me using JuMP. After spending some time to reconcile the .lp outputs of the two models I genuinely believe that…

---

## [How to plot y axis in log form, with differential equations?](https://discourse.julialang.org/t/how-to-plot-y-axis-in-log-form-with-differential-equations/27073)

<div class="topic-metadata">

**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 7\
**Last updated:** [August 2, 2019, 9:13am UTC](https://discourse.julialang.org/t/how-to-plot-y-axis-in-log-form-with-differential-equations/27073 "2019-08-02T09:13:21Z")

</div>

Hello, I would like advice on how to plot the results of differential equations in log format. I have searched the forums and the Plot.jl manual but cannot find an example. I would like to plot the y-axis in log format…

---

## [How to get the number of tracked parameters?](https://discourse.julialang.org/t/how-to-get-the-number-of-tracked-parameters/27096)

<div class="topic-metadata">

**Author:** [@tue](https://discourse.julialang.org/u/tue)\
**Replies:** 4\
**Last updated:** [August 2, 2019, 5:05am UTC](https://discourse.julialang.org/t/how-to-get-the-number-of-tracked-parameters/27096 "2019-08-02T05:05:35Z")

</div>

I’m sure there is a way to get the number of tracked parameters by Flux.Tracker, but so far I still haven’t found any way of actually getting this number. Suppose I make the following: forward = Chain( Conv((5,5), …

---

## [Redis Support?](https://discourse.julialang.org/t/redis-support/27013)

<div class="topic-metadata">

**Author:** [@Samuel\_Stapleton](https://discourse.julialang.org/u/Samuel_Stapleton)\
**Replies:** 1\
**Last updated:** [August 2, 2019, 3:50am UTC](https://discourse.julialang.org/t/redis-support/27013 "2019-08-02T03:50:04Z")

</div>

There were previous discussions to move Redis.jl to JuliaDatabases and to tag a version that supports Julia 1.0, but it appears that the package author never heard back about this original request. Are there plans to con…

---

## [Sparse cholesky factorization with user permutation (Julia 1.1)](https://discourse.julialang.org/t/sparse-cholesky-factorization-with-user-permutation-julia-1-1/27080)

<div class="topic-metadata">

**Author:** [@JuhaHeiskala](https://discourse.julialang.org/u/JuhaHeiskala)\
**Replies:** 1\
**Last updated:** [August 1, 2019, 7:53pm UTC](https://discourse.julialang.org/t/sparse-cholesky-factorization-with-user-permutation-julia-1-1/27080 "2019-08-01T19:53:08Z")

</div>

The sparse cholesky factorization does not generally keep the user permutation given as parameter. SuiteSparse performs post ordering which is not disabled (as far as I can tell) in the current Julia interface to SuiteS…

[Previous page](https://discourse.julialang.org/c/domain/10.md?page=486)

[Next page](https://discourse.julialang.org/c/domain/10.md?page=488)