# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1236

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

**Page:** 1237

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## [Data augmentation question (CIFAR10)](https://discourse.julialang.org/t/data-augmentation-question-cifar10/69667)

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**Author:** [@Rasmus\_Hoier](https://discourse.julialang.org/u/Rasmus_Hoier)\
**Replies:** 9\
**Last updated:** [October 17, 2021, 9:36am UTC](https://discourse.julialang.org/t/data-augmentation-question-cifar10/69667 "2021-10-17T09:36:22Z")

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Hi, I am training a CNN on CIFAR10 (via Flux.DataLoader) and am trying to apply some stochastic data transformations to each batch of data at runtime. My goal is to apply the following operations to each batch I get fr…

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## [Usage of vector of arrays](https://discourse.julialang.org/t/usage-of-vector-of-arrays/69882)

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**Author:** [@Gravlax](https://discourse.julialang.org/u/Gravlax)\
**Replies:** 4\
**Last updated:** [October 17, 2021, 6:35am UTC](https://discourse.julialang.org/t/usage-of-vector-of-arrays/69882 "2021-10-17T06:35:28Z")

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Hi everyone, I am trying to manipulate data using a vector of arrays. The aim is to store the connectivity of a Poisson finite difference stencil using vector of arrays, rather than storing them into independent vectors…

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## [Creating functions exposed to the global scope dynamically?](https://discourse.julialang.org/t/creating-functions-exposed-to-the-global-scope-dynamically/69874)

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**Author:** [@Chris\_Green](https://discourse.julialang.org/u/Chris_Green)\
**Replies:** 4\
**Last updated:** [October 16, 2021, 9:23pm UTC](https://discourse.julialang.org/t/creating-functions-exposed-to-the-global-scope-dynamically/69874 "2021-10-16T21:23:26Z")

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I wanted to use julia+IJulia to easily add a notebook interface/REPL to my large C++ program. I wanted it to be really easy and non-intrusive on the c++ side, and in particular to add no dependencies to the c++ build pr…

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## [Advice on Python co-existing with Julia](https://discourse.julialang.org/t/advice-on-python-co-existing-with-julia/69908)

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**Author:** [@jim-michael](https://discourse.julialang.org/u/jim-michael)\
**Replies:** 2\
**Last updated:** [October 17, 2021, 1:42am UTC](https://discourse.julialang.org/t/advice-on-python-co-existing-with-julia/69908 "2021-10-17T01:42:54Z")

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For those who use local installations of Julia and Python, especially on a Mac Book, I am looking for advice regarding the best installation options for Python. I’ve used Anaconda for several years, and use JupyterLab f…

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## [Broadcasting on Vector{SubString{String}} does not work in Julia 1.7.0 rc1?](https://discourse.julialang.org/t/broadcasting-on-vector-substring-string-does-not-work-in-julia-1-7-0-rc1/69913)

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**Author:** [@pszufe](https://discourse.julialang.org/u/pszufe)\
**Replies:** 12\
**Last updated:** [October 16, 2021, 10:27pm UTC](https://discourse.julialang.org/t/broadcasting-on-vector-substring-string-does-not-work-in-julia-1-7-0-rc1/69913 "2021-10-16T22:27:15Z")

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I use Julia 1.7.0rc1 and it seems that broadcasting works for Vector{String} and does not work on Vector{SubString{String}}. Is this something intended or I run into a bug? For Vector{String} all works as expected: jul…

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## [Embarrassingly parallel multi-threading doesn't scale](https://discourse.julialang.org/t/embarrassingly-parallel-multi-threading-doesnt-scale/69843)

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**Author:** [@Arnau](https://discourse.julialang.org/u/Arnau)\
**Replies:** 17\
**Last updated:** [October 16, 2021, 10:09pm UTC](https://discourse.julialang.org/t/embarrassingly-parallel-multi-threading-doesnt-scale/69843 "2021-10-16T22:09:12Z")

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A simple embarrassingly parallel code, with 4 threads, only halves in speed. Here is a super simplified case :~$ julia -t4 julia\> N = Int(1e8) 100000000 julia\> @elapsed for i in 1:N rand(100) end 46.246…

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## [How to Efficiently Index PyArrays?](https://discourse.julialang.org/t/how-to-efficiently-index-pyarrays/69785)

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**Author:** [@rewindturtle](https://discourse.julialang.org/u/rewindturtle)\
**Replies:** 25\
**Last updated:** [October 16, 2021, 7:59pm UTC](https://discourse.julialang.org/t/how-to-efficiently-index-pyarrays/69785 "2021-10-16T19:59:01Z")

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I have been trying to rewrite a python script I wrote a while back in julia to increase its performance. The python script used a package called gym-retro which ran a videogame emulator that the script could directly int…

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## [Usage of subdirectories to store multiple packages in a single repo](https://discourse.julialang.org/t/usage-of-subdirectories-to-store-multiple-packages-in-a-single-repo/55534)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 11\
**Last updated:** [October 16, 2021, 7:27pm UTC](https://discourse.julialang.org/t/usage-of-subdirectories-to-store-multiple-packages-in-a-single-repo/55534 "2021-10-16T19:27:09Z")

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According to Registrator.jl#287 and Pkg.jl#1422 merged pull requests, several packages can now be organized as subdirectories of a single repo. However, I have not been able to found any detailed docs, which would explai…

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## [Scoping in nested functions - Why am I not getting an error?](https://discourse.julialang.org/t/scoping-in-nested-functions-why-am-i-not-getting-an-error/39354)

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**Author:** [@StevenWhitaker](https://discourse.julialang.org/u/StevenWhitaker)\
**Replies:** 6\
**Last updated:** [October 16, 2021, 6:41pm UTC](https://discourse.julialang.org/t/scoping-in-nested-functions-why-am-i-not-getting-an-error/39354 "2021-10-16T18:41:33Z")

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I am confused about the behavior of scoping when using a nested function. I am using Julia 1.4.1. MWE: function main() function doit() A = ones(Int, 2) # \<-- I expected this to introduce a new A within the…

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## [Function parameter estimation similar to Octave fminsearch](https://discourse.julialang.org/t/function-parameter-estimation-similar-to-octave-fminsearch/69485)

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**Author:** [@John\_Peach](https://discourse.julialang.org/u/John_Peach)\
**Replies:** 4\
**Last updated:** [October 16, 2021, 6:33pm UTC](https://discourse.julialang.org/t/function-parameter-estimation-similar-to-octave-fminsearch/69485 "2021-10-16T18:33:43Z")

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I’m trying to solve a simple parameter estimation problem in Julia similar to how fminsearch works in Octave/Matlab. The RAFF.jl package seemed like a nice approach, but perhaps there’s a better way? For context, I have…

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## [\[ANN\] DataFramesMeta 0.10.0 release](https://discourse.julialang.org/t/ann-dataframesmeta-0-10-0-release/69903)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 4:38pm UTC](https://discourse.julialang.org/t/ann-dataframesmeta-0-10-0-release/69903 "2021-10-16T16:38:53Z")

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We are pleased to announce the release of DataFramesMeta.jl version 0.10.0. This release adds the @astable macro-flag, which is similar to the @t macro-flag in DataFrameMacros.jl. Thanks to @jules for taking initiating …

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## [\*Cache and \*ConstantCache versions of ODE solvers. What is the difference?](https://discourse.julialang.org/t/cache-and-constantcache-versions-of-ode-solvers-what-is-the-difference/69810)

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**Author:** [@Andrey](https://discourse.julialang.org/u/Andrey)\
**Replies:** 1\
**Last updated:** [October 16, 2021, 1:30pm UTC](https://discourse.julialang.org/t/cache-and-constantcache-versions-of-ode-solvers-what-is-the-difference/69810 "2021-10-16T13:30:34Z")

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I was going through Rodas4 solver source code and found that there are 2 different implementations of this solver - Rodas4Cache and Rodas4ConstantCache. Is there any principal difference between these 2 variants? It lo…

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## [Are there prewritten rulesets for SymbolicUtils.jl?](https://discourse.julialang.org/t/are-there-prewritten-rulesets-for-symbolicutils-jl/69890)

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**Author:** [@jedforrest](https://discourse.julialang.org/u/jedforrest)\
**Replies:** 1\
**Last updated:** [October 16, 2021, 1:07pm UTC](https://discourse.julialang.org/t/are-there-prewritten-rulesets-for-symbolicutils-jl/69890 "2021-10-16T13:07:36Z")

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The way I understand SymbolicUtils.jl is that it comes with a basic set of rewriting rules for symbolic expressions, and any other rulesets you want you must provide yourself. For example, you will need to write your own…

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## [Indexing using tuples](https://discourse.julialang.org/t/indexing-using-tuples/69838)

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**Author:** [@larsims](https://discourse.julialang.org/u/larsims)\
**Replies:** 5\
**Last updated:** [October 16, 2021, 12:49pm UTC](https://discourse.julialang.org/t/indexing-using-tuples/69838 "2021-10-16T12:49:55Z")

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I’m trying to use a tuple of strings for indexing a variable (in JuMP). I’m able to loop, etc. but can’t figure out how index a single element. Example, Products is my index tuple, x is my variable. julia\> Products (“P…

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## [Latex rendering in IJulia notebook Markdown cells not working](https://discourse.julialang.org/t/latex-rendering-in-ijulia-notebook-markdown-cells-not-working/69892)

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**Author:** [@mocalvao](https://discourse.julialang.org/u/mocalvao)\
**Replies:** 1\
**Last updated:** [October 16, 2021, 12:28pm UTC](https://discourse.julialang.org/t/latex-rendering-in-ijulia-notebook-markdown-cells-not-working/69892 "2021-10-16T12:28:00Z")

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Hi there, This is probably a very stupid question, but anyhow: I used to have some old Jupyter notebooks for the Julia kernel 1.5.2, which rendered LaTeX excerpts inside Markdown cells seamlessly. I do not remember it …

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## [PES2021 Players Comparison](https://discourse.julialang.org/t/pes2021-players-comparison/69894)

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**Author:** [@cepel](https://discourse.julialang.org/u/cepel)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 12:19pm UTC](https://discourse.julialang.org/t/pes2021-players-comparison/69894 "2021-10-16T12:19:46Z")

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Hey everyone! I developed a dash julia application that allows you to compare PES2021 players on a radar chart. You can select multiple players and update the graph. Feel free to review the code on GitHub and ask me any…

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## [JuMP with absolute value constraint on variables](https://discourse.julialang.org/t/jump-with-absolute-value-constraint-on-variables/69863)

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**Author:** [@qiujj](https://discourse.julialang.org/u/qiujj)\
**Replies:** 2\
**Last updated:** [October 16, 2021, 12:03pm UTC](https://discourse.julialang.org/t/jump-with-absolute-value-constraint-on-variables/69863 "2021-10-16T12:03:48Z")

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I’m trying to optimize a function with absolute constraints on its variable (a\<=|x|\<=b), but I don’t know how to replace function “abs” in JuMP constraint or variable. At first I wrote this one, where x\_min and x\_max ar…

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## [Not a question, but a 3D PlotlyJS gallery](https://discourse.julialang.org/t/not-a-question-but-a-3d-plotlyjs-gallery/65063)

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**Author:** [@empet](https://discourse.julialang.org/u/empet)\
**Replies:** 7\
**Last updated:** [October 16, 2021, 11:20am UTC](https://discourse.julialang.org/t/not-a-question-but-a-3d-plotlyjs-gallery/65063 "2021-10-16T11:20:00Z")

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I’m a Julia beginner, as you may have noticed from the basic questions I have asked here. To practice it I created a small project and gallery of 3D PlotlyJS charts, here: https://github.com/empet/3D-Viz-with-PlotlyJ…

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## [Optimizing model description](https://discourse.julialang.org/t/optimizing-model-description/69885)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 0\
**Last updated:** [October 16, 2021, 11:05am UTC](https://discourse.julialang.org/t/optimizing-model-description/69885 "2021-10-16T11:05:52Z")

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I need to optimize a model description for an ODEProblem, which is a hand-coded discretization of a PDE (so the state is a matrix). I know I should… avoid creating arrays in the model. My plan is to instead operate on …

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## [MATLAB.jl question: where to add the Matlab application path?](https://discourse.julialang.org/t/matlab-jl-question-where-to-add-the-matlab-application-path/69872)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 2\
**Last updated:** [October 16, 2021, 9:20am UTC](https://discourse.julialang.org/t/matlab-jl-question-where-to-add-the-matlab-application-path/69872 "2021-10-16T09:20:33Z")

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I have a Macbook Pro and want to install MATLAB.jl. The instructions say this: You may add the following command to .profile:export MATLAB\_HOME=/Applications/MATLAB\_R2012b.app . Should I do this through Julia or my Te…

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## [Creating and publishing my Very First Package](https://discourse.julialang.org/t/creating-and-publishing-my-very-first-package/69831)

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**Author:** [@Niall](https://discourse.julialang.org/u/Niall)\
**Replies:** 11\
**Last updated:** [October 16, 2021, 7:47am UTC](https://discourse.julialang.org/t/creating-and-publishing-my-very-first-package/69831 "2021-10-16T07:47:12Z")

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Hi. I’m climbing up the wall a bit here. I’ve never created a package before, so I want to create one, simply to work out how to work with packages, but I’ve come to a complete standstill. I’ve viewed about 20 different …

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## [Using PPOPolicy with custom environment with action masking in ReinforcementLearning.jl](https://discourse.julialang.org/t/using-ppopolicy-with-custom-environment-with-action-masking-in-reinforcementlearning-jl/69625)

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**Author:** [@mfg](https://discourse.julialang.org/u/mfg)\
**Replies:** 14\
**Last updated:** [October 16, 2021, 3:30am UTC](https://discourse.julialang.org/t/using-ppopolicy-with-custom-environment-with-action-masking-in-reinforcementlearning-jl/69625 "2021-10-16T03:30:47Z")

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In order to use Action Masking with he PPOPolicy i think i have to use a MaskedPPOTrajectory. The legal\_actions\_mask gets updated in the update! function with the result of legal\_action\_space\_mask(env), but afaiu this sh…

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## [Would anyone please help me with this Boolean related error?](https://discourse.julialang.org/t/would-anyone-please-help-me-with-this-boolean-related-error/69856)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 6\
**Last updated:** [October 16, 2021, 3:25am UTC](https://discourse.julialang.org/t/would-anyone-please-help-me-with-this-boolean-related-error/69856 "2021-10-16T03:25:52Z")

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Anyone knows why I keep getting an error for the below simple function: A = \[15, 16, -30\]; B = \[12, 35, 38\]; Ind = A .\> -20 && B .\>= 15 Here is the error: TypeError: non-boolean (BitVector) used in boolean context St…

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## [Could we make first-class support for packages that are "just files" and not repositories?](https://discourse.julialang.org/t/could-we-make-first-class-support-for-packages-that-are-just-files-and-not-repositories/36931)

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**Author:** [@tuckermcclure](https://discourse.julialang.org/u/tuckermcclure)\
**Replies:** 21\
**Last updated:** [October 16, 2021, 2:37am UTC](https://discourse.julialang.org/t/could-we-make-first-class-support-for-packages-that-are-just-files-and-not-repositories/36931 "2021-10-16T02:37:03Z")

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I keep circling around the same issue from a variety of different vantage points, and I think that having first-class support for local, unregistered packages (just local files, not repositories) would solve a lot of pro…

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## [ANN: DashVtk.jl - interactive visualization of VTK data structures in Dash web apps in Julia](https://discourse.julialang.org/t/ann-dashvtk-jl-interactive-visualization-of-vtk-data-structures-in-dash-web-apps-in-julia/66626)

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**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 3\
**Last updated:** [October 16, 2021, 12:38am UTC](https://discourse.julialang.org/t/ann-dashvtk-jl-interactive-visualization-of-vtk-data-structures-in-dash-web-apps-in-julia/66626 "2021-10-16T00:38:40Z")

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VTK is a visualization software and data representation standard for 2D and 3D data, e.g. 2D/3D meshes, images, scalar-valued fields, vector-valued fields, etc. I am happy to announce that using DashVtk.jl, it’s extremel…

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## [Do Bool values separated by semi-colon and comma different from each other?](https://discourse.julialang.org/t/do-bool-values-separated-by-semi-colon-and-comma-different-from-each-other/69864)

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**Author:** [@leon](https://discourse.julialang.org/u/leon)\
**Replies:** 2\
**Last updated:** [October 16, 2021, 12:23am UTC](https://discourse.julialang.org/t/do-bool-values-separated-by-semi-colon-and-comma-different-from-each-other/69864 "2021-10-16T00:23:06Z")

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I have a matrix T0 (size: 1334269 x 35). It was created by this: T0 = hcat(A, B, C, D, E, ...); # A, B, C, D, E, .. are all single-column data. My goal is to only get the rows meeting these requirements: Ind = map(A, …

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## [Julia Manual GMM](https://discourse.julialang.org/t/julia-manual-gmm/10487)

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**Author:** [@James\_Stewart](https://discourse.julialang.org/u/James_Stewart)\
**Replies:** 18\
**Last updated:** [October 16, 2021, 12:04am UTC](https://discourse.julialang.org/t/julia-manual-gmm/10487 "2021-10-16T00:04:36Z")

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Hey I am having a bit of trouble understanding how to manually do GMM and in particular how to do GMM in Julia. Here is the Stata code + data: use http://www.stata-press.com/data/r13/docvisits gmm (docvis - exp({xb:…

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## [Hyperlink to Pluto notebook](https://discourse.julialang.org/t/hyperlink-to-pluto-notebook/69818)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 8\
**Last updated:** [October 15, 2021, 11:42pm UTC](https://discourse.julialang.org/t/hyperlink-to-pluto-notebook/69818 "2021-10-15T23:42:14Z")

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Hi all, In Jupyter, it is possible to link one notebook to another using relative paths. However, this does not appear to work with Pluto. Here is what I tried: md""" # \[my link\]("my\_notebook.jl") """ The linked page …

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## [Interval Compiler for Sound Float Computations](https://discourse.julialang.org/t/interval-compiler-for-sound-float-computations/69857)

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**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 0\
**Last updated:** [October 15, 2021, 9:38pm UTC](https://discourse.julialang.org/t/interval-compiler-for-sound-float-computations/69857 "2021-10-15T21:38:55Z")

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For those interested in llvm mods for enhancing floats. IGen is a source-to-source compiler for interval arithmetic. IGen takes as input a C function doing floating-point computations, possibly using SIMD intrinsics, a…

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## [Clarification of Abstract Type and Specialized Code](https://discourse.julialang.org/t/clarification-of-abstract-type-and-specialized-code/67289)

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**Author:** [@anon60034542](https://discourse.julialang.org/u/anon60034542)\
**Replies:** 6\
**Last updated:** [October 15, 2021, 6:06pm UTC](https://discourse.julialang.org/t/clarification-of-abstract-type-and-specialized-code/67289 "2021-10-15T18:06:05Z")

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In the performance tips, under Annotate values taken from untyped locations, it says: Type annotation will not enhance (and can actually hinder) performance if the type is abstract, or constructed at run-time. This is …

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