# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1866

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

**Page:** 1867

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## [\[ANN\] ARCHModels.jl](https://discourse.julialang.org/t/ann-archmodels-jl/21348)

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**Author:** [@s-broda](https://discourse.julialang.org/u/s-broda)\
**Replies:** 9\
**Last updated:** [December 9, 2019, 12:42pm UTC](https://discourse.julialang.org/t/ann-archmodels-jl/21348 "2019-12-09T12:42:26Z")

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I am happy to announce that ARCHModels.jl just had its v0.1.0 release. ARCH (Autoregressive Conditional Volatility) models are the workhorse tools for modelling daily volatility in financial time series data. ARCHModels.…

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## [Need help with prod() or any custom function with JuMP](https://discourse.julialang.org/t/need-help-with-prod-or-any-custom-function-with-jump/31962)

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**Author:** [@Xentios](https://discourse.julialang.org/u/Xentios)\
**Replies:** 7\
**Last updated:** [December 9, 2019, 12:14pm UTC](https://discourse.julialang.org/t/need-help-with-prod-or-any-custom-function-with-jump/31962 "2019-12-09T12:14:36Z")

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All I want is to be able to run an optimization which can use prod() or any custom function i can make. I tried everything normal and NL objectives, constraints vs… Ipopt optimizer does what i want but it does with fl…

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## [Agent Based Modeling in Julia](https://discourse.julialang.org/t/agent-based-modeling-in-julia/12431)

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**Author:** [@sbacelar](https://discourse.julialang.org/u/sbacelar)\
**Replies:** 47\
**Last updated:** [December 9, 2019, 11:32am UTC](https://discourse.julialang.org/t/agent-based-modeling-in-julia/12431 "2019-12-09T11:32:20Z")

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I couldn’t find “established” packages on Agent-Based Modeling (ABM) in Julia. Is there any work that it is interesting to follow on this subject? And also, is there any Julia interface to \[NetLogo\](https://ccl.northwes…

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## [Agents.jl : Agent based modelling](https://discourse.julialang.org/t/agents-jl-agent-based-modelling/32043)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 0\
**Last updated:** [December 9, 2019, 11:28am UTC](https://discourse.julialang.org/t/agents-jl-agent-based-modelling/32043 "2019-12-09T11:28:57Z")

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Heyo people, I am very happy to announce Agents.jl v2.0 (actually version 1 was never announced). Agents.jl allows you to do agent based modelling. From our documentation: An agent-based model is a computational s…

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## [How to specify that a function which has several (but a limited amount) of possible types as inputs and outputs?](https://discourse.julialang.org/t/how-to-specify-that-a-function-which-has-several-but-a-limited-amount-of-possible-types-as-inputs-and-outputs/32041)

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**Author:** [@gobs](https://discourse.julialang.org/u/gobs)\
**Replies:** 2\
**Last updated:** [December 9, 2019, 11:02am UTC](https://discourse.julialang.org/t/how-to-specify-that-a-function-which-has-several-but-a-limited-amount-of-possible-types-as-inputs-and-outputs/32041 "2019-12-09T11:02:04Z")

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My code for formulating a specific JuMP optimisation model has started getting quite slow, and I would like to start optimising it by specifying types. One of the main functions I call just searches through two dictiona…

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## [Problems with Gettext and Formatting on Master](https://discourse.julialang.org/t/problems-with-gettext-and-formatting-on-master/32037)

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**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 2\
**Last updated:** [December 9, 2019, 10:43am UTC](https://discourse.julialang.org/t/problems-with-gettext-and-formatting-on-master/32037 "2019-12-09T10:43:53Z")

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I reported an issue with testing ImageView which apparently has been fixed but for me it persists. After a complete reinstall of master Version 1.4.0-DEV.564 (2019-12-08) I tried again but still the same problems. Drilli…

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## [Error Plotting](https://discourse.julialang.org/t/error-plotting/32039)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 3\
**Last updated:** [December 9, 2019, 9:54am UTC](https://discourse.julialang.org/t/error-plotting/32039 "2019-12-09T09:54:45Z")

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I am trying to plot a Vector of arrays, θₜ=Vector{Float64}\[\] It has 29 arrays of 100 elements each, and when I try to plot using the following, it throws an error: using Plots plot(1:1:29,θₜ\[1:1:29\],legend=false) Err…

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## [How to simplify symbolic expression using Calculusjl](https://discourse.julialang.org/t/how-to-simplify-symbolic-expression-using-calculusjl/32036)

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**Author:** [@ASF](https://discourse.julialang.org/u/ASF)\
**Replies:** 1\
**Last updated:** [December 9, 2019, 7:07am UTC](https://discourse.julialang.org/t/how-to-simplify-symbolic-expression-using-calculusjl/32036 "2019-12-09T07:07:22Z")

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Here is a very simple example of what im doing: using Calculus Calculus.differentiate("286-20\*x^2", :x) |\> simplify |\> eval :(-(20 \* (2x))) UndefVarError: x not defined Is there any way to further simplify this to -…

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## [How can I create a function type with custom Input and Output type](https://discourse.julialang.org/t/how-can-i-create-a-function-type-with-custom-input-and-output-type/31719)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 9\
**Last updated:** [December 9, 2019, 4:24am UTC](https://discourse.julialang.org/t/how-can-i-create-a-function-type-with-custom-input-and-output-type/31719 "2019-12-09T04:24:05Z")

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– advanced question – Let’s say, I have a Vector{Int} and would like to transform it into a Vector{Float64}. One super generic way to do it is to use the hidden return\_type function Core.Compiler.return\_type. Namely wi…

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## [Basic Performance Analysis Package](https://discourse.julialang.org/t/basic-performance-analysis-package/32032)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 3\
**Last updated:** [December 9, 2019, 12:57am UTC](https://discourse.julialang.org/t/basic-performance-analysis-package/32032 "2019-12-09T00:57:35Z")

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I was wondering if there is a package to test my code to point out the common pitfalls that slows down my code? Like type instability and boxing and unboxing and etc??? Thanks

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## [Repeating a for loop sequence](https://discourse.julialang.org/t/repeating-a-for-loop-sequence/32008)

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**Author:** [@WEEZEERAE](https://discourse.julialang.org/u/WEEZEERAE)\
**Replies:** 5\
**Last updated:** [December 8, 2019, 9:49pm UTC](https://discourse.julialang.org/t/repeating-a-for-loop-sequence/32008 "2019-12-08T21:49:29Z")

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Hey people, I basically want to include an if condition into my for loop, which repeats the loop with the previews iteration variable, if the condition hasn’t been satisfied. In this case there are a few things to cons…

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## [PackageCompiler: LLVM ERROR](https://discourse.julialang.org/t/packagecompiler-llvm-error/32016)

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**Author:** [@rssdev10](https://discourse.julialang.org/u/rssdev10)\
**Replies:** 1\
**Last updated:** [December 8, 2019, 9:08pm UTC](https://discourse.julialang.org/t/packagecompiler-llvm-error/32016 "2019-12-08T21:08:03Z")

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Hi, I’m getting the following error while compiling my package: ptrtoint not supported for non-integral pointers inttoptr not supported for non-integral pointers ptrtoint not supported for non-integral pointers inttoptr…

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## [Axpby! and 0\*NaN](https://discourse.julialang.org/t/axpby-and-0-nan/32014)

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**Author:** [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)\
**Replies:** 2\
**Last updated:** [December 8, 2019, 7:32pm UTC](https://discourse.julialang.org/t/axpby-and-0-nan/32014 "2019-12-08T19:32:36Z")

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There might be some inconsistencies regarding 0\*NaN: if one has p = 0\*NaN, then p is also NaN (ok, treating this as julia convention), however, using LinearAlgebra x = rand(2,2) y = rand(2,2) y\[1,1\] = NaN axpby!(.3, x,…

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## [Plot Labels](https://discourse.julialang.org/t/plot-labels/32019)

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**Author:** [@martingalemeasure](https://discourse.julialang.org/u/martingalemeasure)\
**Replies:** 3\
**Last updated:** [December 8, 2019, 6:18pm UTC](https://discourse.julialang.org/t/plot-labels/32019 "2019-12-08T18:18:46Z")

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When I run plot(\[1,2,3\], labels=\["abc"\]) The chart shows a legend with — \[“abc”\] instead of — abc.

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## [Julia 1.3.0 documentation PDF link gets "404: Not found"](https://discourse.julialang.org/t/julia-1-3-0-documentation-pdf-link-gets-404-not-found/32017)

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**Author:** [@DaymondLing](https://discourse.julialang.org/u/DaymondLing)\
**Replies:** 0\
**Last updated:** [December 8, 2019, 3:38pm UTC](https://discourse.julialang.org/t/julia-1-3-0-documentation-pdf-link-gets-404-not-found/32017 "2019-12-08T15:38:30Z")

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Not sure where to post this, the PDF documentation link for Julia 1.3.0 is broken

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## [Looking for a speaker for an academic seminar on blockchains and markets](https://discourse.julialang.org/t/looking-for-a-speaker-for-an-academic-seminar-on-blockchains-and-markets/32010)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 0\
**Last updated:** [December 8, 2019, 2:00pm UTC](https://discourse.julialang.org/t/looking-for-a-speaker-for-an-academic-seminar-on-blockchains-and-markets/32010 "2019-12-08T14:00:50Z")

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Hello, here at the Bureau d’Economie Théorique et Appliquée of Nancy (NE France) we are starting the planning of seminars for next academic year, and we would be interested in having a speaker (normally a PhD student or…

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## [How to convert a Dict to a Vector of NamedTuples?](https://discourse.julialang.org/t/how-to-convert-a-dict-to-a-vector-of-namedtuples/32005)

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**Author:** [@Elmer\_Cusipuma](https://discourse.julialang.org/u/Elmer_Cusipuma)\
**Replies:** 1\
**Last updated:** [December 8, 2019, 1:00pm UTC](https://discourse.julialang.org/t/how-to-convert-a-dict-to-a-vector-of-namedtuples/32005 "2019-12-08T13:00:53Z")

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I am trying to do the following julia\> dict = Dict(1 =\> Dict("a"=\> (n=1.9,t=2), "b" =\> (n=3.1,t=5) ), 2 =\> Dict("a"=\> (n=6.6,t=5), "b" =\> (n=3.9,t=6) )); julia\> tbl = \[(jt=k,case=cs,v\[cs\]...) for (k,…

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## [How to store the set of needed packages in git](https://discourse.julialang.org/t/how-to-store-the-set-of-needed-packages-in-git/31975)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 20\
**Last updated:** [December 8, 2019, 7:43am UTC](https://discourse.julialang.org/t/how-to-store-the-set-of-needed-packages-in-git/31975 "2019-12-08T07:43:08Z")

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I know the possibility to “instantiate” a folder/project to load all the correct package versions, that are needed. But how can I do the opposite, store a set of packages in a file that I can commit to git? Uwe

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## [Create Sparse Array without Copying](https://discourse.julialang.org/t/create-sparse-array-without-copying/31984)

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**Author:** [@Paul\_McVay](https://discourse.julialang.org/u/Paul_McVay)\
**Replies:** 5\
**Last updated:** [December 8, 2019, 7:40am UTC](https://discourse.julialang.org/t/create-sparse-array-without-copying/31984 "2019-12-08T07:40:02Z")

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I have the row vector, column vector and the value vectors of a sparse matrix and would like to create a sparse matrix with them without copying the vectors because the vectors already take up 59% of my systems memory. I…

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## [Tables package for fast grouping and filtering?](https://discourse.julialang.org/t/tables-package-for-fast-grouping-and-filtering/31950)

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**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 18\
**Last updated:** [December 8, 2019, 6:40am UTC](https://discourse.julialang.org/t/tables-package-for-fast-grouping-and-filtering/31950 "2019-12-08T06:40:10Z")

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I already use Julia for much of my simulation and model calibration work, but am considering using it for some of the more basic data preparation I do. This work is primarly filtering, grouping, and applying time series…

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## [Trying to understand optimization via multiple dispatch and type stability](https://discourse.julialang.org/t/trying-to-understand-optimization-via-multiple-dispatch-and-type-stability/31991)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 5\
**Last updated:** [December 8, 2019, 5:28am UTC](https://discourse.julialang.org/t/trying-to-understand-optimization-via-multiple-dispatch-and-type-stability/31991 "2019-12-08T05:28:16Z")

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(Word of warning, I’m not well-versed in programming in general and have only used Python for simple tasks, so it would be helpful for me if even simple concepts are explained with some detail.) I’m interested in trying…

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## [Help converting python to julia?](https://discourse.julialang.org/t/help-converting-python-to-julia/31998)

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**Author:** [@PseudoCodeNerd](https://discourse.julialang.org/u/PseudoCodeNerd)\
**Replies:** 2\
**Last updated:** [December 8, 2019, 4:46am UTC](https://discourse.julialang.org/t/help-converting-python-to-julia/31998 "2019-12-08T04:46:00Z")

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Hello There, after my previous post I tried learning ReGeX to do the acronym thing I was trying to do. I was able to write a python code for the same which works right ! Julia documentation was not clear to me… Can y…

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## [sum(Array{Bool,1}) vs sum(Array(Int8,1})](https://discourse.julialang.org/t/sum-array-bool-1-vs-sum-array-int8-1/31353)

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**Author:** [@recri](https://discourse.julialang.org/u/recri)\
**Replies:** 6\
**Last updated:** [December 8, 2019, 3:43am UTC](https://discourse.julialang.org/t/sum-array-bool-1-vs-sum-array-int8-1/31353 "2019-12-08T03:43:56Z")

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I was reviewing old discussions around efficiency and I noticed that summing an array of Bool is still slower (julia-1.3.0-rc5) than summing the same array of values as Int8, which is puzzling since it seems it should in…

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## [How to improve JIT compile performance for local julia scripts](https://discourse.julialang.org/t/how-to-improve-jit-compile-performance-for-local-julia-scripts/31995)

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**Author:** [@AtsushiSakai](https://discourse.julialang.org/u/AtsushiSakai)\
**Replies:** 0\
**Last updated:** [December 8, 2019, 1:44am UTC](https://discourse.julialang.org/t/how-to-improve-jit-compile-performance-for-local-julia-scripts/31995 "2019-12-08T01:44:05Z")

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I have a question about JIT compile performance improvement. The official doc has performance tips: https://docs.julialang.org/en/v1/manual/performance-tips/index.html But, in my understanding, this tips are for runti…

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## [A version of sparse! that updates a previously existing SparseMatrixCSC?](https://discourse.julialang.org/t/a-version-of-sparse-that-updates-a-previously-existing-sparsematrixcsc/31943)

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**Author:** [@Bruno\_Amorim](https://discourse.julialang.org/u/Bruno_Amorim)\
**Replies:** 2\
**Last updated:** [December 8, 2019, 12:57am UTC](https://discourse.julialang.org/t/a-version-of-sparse-that-updates-a-previously-existing-sparsematrixcsc/31943 "2019-12-08T00:57:31Z")

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I will start with some context: I am dealing with a problem where I have to diagonalize a matrix H for diferent values of a parameter k. I know that the matrix H is sparse, but I do not now a priori either the structure…

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## [Starting a Deep Learning project, should I keep using Julia or jump to Python?](https://discourse.julialang.org/t/starting-a-deep-learning-project-should-i-keep-using-julia-or-jump-to-python/3840)

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**Author:** [@raff](https://discourse.julialang.org/u/raff)\
**Replies:** 15\
**Last updated:** [December 8, 2019, 12:33am UTC](https://discourse.julialang.org/t/starting-a-deep-learning-project-should-i-keep-using-julia-or-jump-to-python/3840 "2019-12-08T00:33:13Z")

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I fully switched from Matlab to Julia to do my machine learning research two years ago. I really like Julia and never look back since then. With Julia, my workflow is more productive than before. But now, I will start a…

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## [Representing c unions and packed types](https://discourse.julialang.org/t/representing-c-unions-and-packed-types/31993)

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**Author:** [@cshenton](https://discourse.julialang.org/u/cshenton)\
**Replies:** 0\
**Last updated:** [December 8, 2019, 12:32am UTC](https://discourse.julialang.org/t/representing-c-unions-and-packed-types/31993 "2019-12-08T00:32:47Z")

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I’m currently writing language bindings for OpenVR to integrate with the Julia game engine I’m building. I’ve run into two challenges: The API uses (quite large) union types for its event system The API uses pragma pa…

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## [Creating an i/o pipeline which feeds a while loop using multiple cores](https://discourse.julialang.org/t/creating-an-i-o-pipeline-which-feeds-a-while-loop-using-multiple-cores/31931)

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**Author:** [@anon97116444](https://discourse.julialang.org/u/anon97116444)\
**Replies:** 6\
**Last updated:** [December 8, 2019, 12:18am UTC](https://discourse.julialang.org/t/creating-an-i-o-pipeline-which-feeds-a-while-loop-using-multiple-cores/31931 "2019-12-08T00:18:45Z")

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no code written YET but getting there. So I am having a little performance anxiety and I think it’s because I’m not seeing the big picture yet. Could someone point me at ANY Julia modules I should look at for the follow…

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## [Two minute papers video about AI](https://discourse.julialang.org/t/two-minute-papers-video-about-ai/31949)

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**Author:** [@Iagoba\_Apellaniz](https://discourse.julialang.org/u/Iagoba_Apellaniz)\
**Replies:** 6\
**Last updated:** [December 7, 2019, 10:36pm UTC](https://discourse.julialang.org/t/two-minute-papers-video-about-ai/31949 "2019-12-07T22:36:03Z")

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Which language are they using? Is it Julia? It seems quite similar.

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## [Having trouble pushing to an array of arrays](https://discourse.julialang.org/t/having-trouble-pushing-to-an-array-of-arrays/31971)

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**Author:** [@fibonatic](https://discourse.julialang.org/u/fibonatic)\
**Replies:** 7\
**Last updated:** [December 7, 2019, 6:39pm UTC](https://discourse.julialang.org/t/having-trouble-pushing-to-an-array-of-arrays/31971 "2019-12-07T18:39:56Z")

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I am trying to fill in an array of arrays using push. If I manually initialize the array of arrays pushing works, but it doesn’t if I try to initialize using fill. For example manually initializing test = \[Int\[\], Int\[\]\]…

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