# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1777

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

**Page:** 1778

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## [Using ForwardDiff to differentiate an ODE with respect to some of its parameters](https://discourse.julialang.org/t/using-forwarddiff-to-differentiate-an-ode-with-respect-to-some-of-its-parameters/37353)

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**Author:** [@peterj](https://discourse.julialang.org/u/peterj)\
**Replies:** 5\
**Last updated:** [April 10, 2020, 6:38pm UTC](https://discourse.julialang.org/t/using-forwarddiff-to-differentiate-an-ode-with-respect-to-some-of-its-parameters/37353 "2020-04-10T18:38:35Z")

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So far, I have this using DifferentialEquations using LabelledArrays const n = 10 struct params p\_to\_optimize\_array::AbstractArray{\<:Real,1} p\_constant\_array::AbstractArray{\<:Real,1} end function f1(du,u…

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## [Getting julia-lsp working with emacs](https://discourse.julialang.org/t/getting-julia-lsp-working-with-emacs/37423)

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**Author:** [@Zlass](https://discourse.julialang.org/u/Zlass)\
**Replies:** 1\
**Last updated:** [April 12, 2020, 12:08am UTC](https://discourse.julialang.org/t/getting-julia-lsp-working-with-emacs/37423 "2020-04-12T00:08:55Z")

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Fairly new to julia and emacs. Have spent the afternoon trying to get everything work, but I’m stuck. I’m using spacemacs and followed their doc here to set up the language features. That part seems to be working. Howev…

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## [String indexing](https://discourse.julialang.org/t/string-indexing/37403)

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**Author:** [@georgegi86](https://discourse.julialang.org/u/georgegi86)\
**Replies:** 11\
**Last updated:** [April 11, 2020, 10:47pm UTC](https://discourse.julialang.org/t/string-indexing/37403 "2020-04-11T22:47:15Z")

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Hi all, playing with Julia today with some limited Python and R experience. How does Julia perform indexing from the end, up to the end minus some value but conditional on the length. Example: strings = \[“name”, “veryla…

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## [Set Julia path in Juno](https://discourse.julialang.org/t/set-julia-path-in-juno/37417)

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**Author:** [@alessandro\_di\_nola](https://discourse.julialang.org/u/alessandro_di_nola)\
**Replies:** 1\
**Last updated:** [April 11, 2020, 9:26pm UTC](https://discourse.julialang.org/t/set-julia-path-in-juno/37417 "2020-04-11T21:26:24Z")

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Dear users, I have a problem regarding the installation of Julia and Atom-Juno. I followed the steps described in http://docs.junolab.org/stable/man/installation/index.html. Then I ran Julia but I got the following erro…

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## [Problem: extracting a row from an array, returns a column](https://discourse.julialang.org/t/problem-extracting-a-row-from-an-array-returns-a-column/37331)

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**Author:** [@AIRoebl](https://discourse.julialang.org/u/AIRoebl)\
**Replies:** 13\
**Last updated:** [April 11, 2020, 9:11pm UTC](https://discourse.julialang.org/t/problem-extracting-a-row-from-an-array-returns-a-column/37331 "2020-04-11T21:11:41Z")

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In Julia 1.4.0, attempting to extract a row from an array returns a vector/column, and not a row. From array: N = \[1 2;3 4\] 2×2 Array{Int64,2}: 1 2 3 4 N\[1,:\] 2-element Array{Int64,1}: 1 2 It returns a colum…

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## [CharNN in Flux zoo](https://discourse.julialang.org/t/charnn-in-flux-zoo/37375)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 1\
**Last updated:** [April 11, 2020, 7:42pm UTC](https://discourse.julialang.org/t/charnn-in-flux-zoo/37375 "2020-04-11T19:42:52Z")

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Hi, I am running charNN from the Flux Zoo and come across the error in the loss function: Flux.truncate!() not found. I found out that this function existed in Julia 0.4 and reset the gradients in a model. This functi…

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## [Unable to install unregistered package RegTools](https://discourse.julialang.org/t/unable-to-install-unregistered-package-regtools/37406)

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**Author:** [@Alex\_Tantos](https://discourse.julialang.org/u/Alex_Tantos)\
**Replies:** 7\
**Last updated:** [April 11, 2020, 6:29pm UTC](https://discourse.julialang.org/t/unable-to-install-unregistered-package-regtools/37406 "2020-04-11T18:29:07Z")

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Hi there! Am trying to install an unregistered package that lies on a repo, called RegTools. I try to Pkg.add(PackageSpec(url="https://github.com/wakakusa/RegTools/blob/master/src/RegTools.jl")) but I get the following …

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## [Gaston to plot Cobb Douglas, not sure how to set scale](https://discourse.julialang.org/t/gaston-to-plot-cobb-douglas-not-sure-how-to-set-scale/37369)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 3\
**Last updated:** [April 11, 2020, 5:16pm UTC](https://discourse.julialang.org/t/gaston-to-plot-cobb-douglas-not-sure-how-to-set-scale/37369 "2020-04-11T17:16:41Z")

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I’m trying to model the above function L= 0:600 K=0:600 Q=0:8000 surf(L, K, (L,K)-\>.1\*K^.5\*L^1.5, title="Cobb Douglas", plotstyle="lines", linecolor="magenta", gpcom="unset colorbox") surf!(x,y,(x,y)-\>cos.(x/…

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## [Randn types, @which](https://discourse.julialang.org/t/randn-types-which/37397)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 5:01pm UTC](https://discourse.julialang.org/t/randn-types-which/37397 "2020-04-11T17:01:00Z")

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I am exploring the relationship between a method call, and the particular method chosen. So consider @which randn(Int64, 3, 4, 2) which returns randn(::Type{T}, dims::Integer...) where T in Random at /Users/julia/buil…

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## [Extracting kwargs from anonymous function](https://discourse.julialang.org/t/extracting-kwargs-from-anonymous-function/37350)

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**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 12\
**Last updated:** [April 11, 2020, 4:08pm UTC](https://discourse.julialang.org/t/extracting-kwargs-from-anonymous-function/37350 "2020-04-11T16:08:44Z")

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EDIT: original title was “Confused about escaping in macros” I’m trying metaprogramming in Julia for the first time, and I’m having some trouble grasping the escaping and hygiene discussion in the manual. I’m trying to…

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## [Sparse Cholesky of Gram Matrix (SuiteSparse?)](https://discourse.julialang.org/t/sparse-cholesky-of-gram-matrix-suitesparse/37303)

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**Author:** [@guille](https://discourse.julialang.org/u/guille)\
**Replies:** 25\
**Last updated:** [April 11, 2020, 3:07pm UTC](https://discourse.julialang.org/t/sparse-cholesky-of-gram-matrix-suitesparse/37303 "2020-04-11T15:07:47Z")

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Hey all! I have a quick question, which I saw was referenced here some time ago. I was wondering if there was a standard way of factorizing A^TA (i.e. the Gram matrix of A) without actively computing the Gram matrix? Th…

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## [Can not add new packages on Manjaro Linux](https://discourse.julialang.org/t/can-not-add-new-packages-on-manjaro-linux/37373)

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**Author:** [@Tofi](https://discourse.julialang.org/u/Tofi)\
**Replies:** 8\
**Last updated:** [April 11, 2020, 12:45pm UTC](https://discourse.julialang.org/t/can-not-add-new-packages-on-manjaro-linux/37373 "2020-04-11T12:45:14Z")

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I just installed Julia 1.4 from the Manjaro Linux repository. When I try to add new packages to Julia, I get an error message: (@v1.4) pkg\> add Plots Cloning default registries into \`~/.julia\` Cloning registry f…

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## [Flux.chunk error?](https://discourse.julialang.org/t/flux-chunk-error/37358)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 12:24pm UTC](https://discourse.julialang.org/t/flux-chunk-error/37358 "2020-04-11T12:24:23Z")

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Here is some code: chunk\[1:20,6) which returns: \[1, 2, 3, 4\] \[5, 6, 7, 8\] \[9, 10, 11, 12\] \[13, 14, 15, 16\] \[17, 18, 19, 20\] That is only 5 chunks, and I expect 6. Why not return \[1,2,3,4\] \[6,7,8,9\] \[11…

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## [Change thickness of axises in plots](https://discourse.julialang.org/t/change-thickness-of-axises-in-plots/37387)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 0\
**Last updated:** [April 11, 2020, 11:21am UTC](https://discourse.julialang.org/t/change-thickness-of-axises-in-plots/37387 "2020-04-11T11:21:56Z")

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Hello, how do I change the thickness of the axes when I make a plot (without changes the thickness of texts, ticks, etc.)?

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## [Juno shortcut to hide REPL](https://discourse.julialang.org/t/juno-shortcut-to-hide-repl/36671)

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**Author:** [@sijo](https://discourse.julialang.org/u/sijo)\
**Replies:** 3\
**Last updated:** [April 11, 2020, 9:13am UTC](https://discourse.julialang.org/t/juno-shortcut-to-hide-repl/36671 "2020-04-11T09:13:12Z")

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While editing I like to expand the editor area used to display code… Is there a way to quickly hide the REPL panel from the keyboard?

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## [How to test the value of a variable from info log](https://discourse.julialang.org/t/how-to-test-the-value-of-a-variable-from-info-log/37380)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 7:27am UTC](https://discourse.julialang.org/t/how-to-test-the-value-of-a-variable-from-info-log/37380 "2020-04-11T07:27:00Z")

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Is there any way to test the appearance of a string inside one of the variables being printed from @info? In the example below, I want to test the string world appearing in the info log. I don’t really care where it ap…

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## [What did I do wrong with LAPACK.potri!?](https://discourse.julialang.org/t/what-did-i-do-wrong-with-lapack-potri/37293)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 7:15am UTC](https://discourse.julialang.org/t/what-did-i-do-wrong-with-lapack-potri/37293 "2020-04-11T07:15:49Z")

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Somehow potri is not giving me the inverse. What did I do wrong? Here is an example: using LinearAlgebra, Random Random.seed!(1) x = rand(5, 5) V = x'x LinearAlgebra.copytri!(V, 'U') Vcopy = rand(5, 5) copyto!(Vcopy, V…

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## [Announcing Traits.jl - a revival of Julia traits](https://discourse.julialang.org/t/announcing-traits-jl-a-revival-of-julia-traits/35683)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 21\
**Last updated:** [April 11, 2020, 6:52am UTC](https://discourse.julialang.org/t/announcing-traits-jl-a-revival-of-julia-traits/35683 "2020-04-11T06:52:24Z")

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Dear Julia community, Today I want to announce a package of mine, GitHub - schlichtanders/Traits.jl: traits for julia: dispatch on whatever you want After more than a year of intense experimenting with traits in Julia,…

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## [Proper way to use modules](https://discourse.julialang.org/t/proper-way-to-use-modules/28909)

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**Author:** [@rwgardner](https://discourse.julialang.org/u/rwgardner)\
**Replies:** 12\
**Last updated:** [April 11, 2020, 6:44am UTC](https://discourse.julialang.org/t/proper-way-to-use-modules/28909 "2020-04-11T06:44:29Z")

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With julia \<=0.6, I used to bring in all my modules in one place and then I would import the loaded modules within other modules as needed with “import …Mod1” as below. #my\_main.jl push!(LOAD\_PATH, Base.source\_dir()) …

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## [Magic incantations to make a local module work](https://discourse.julialang.org/t/magic-incantations-to-make-a-local-module-work/36994)

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**Author:** [@lewis](https://discourse.julialang.org/u/lewis)\
**Replies:** 10\
**Last updated:** [April 11, 2020, 6:42am UTC](https://discourse.julialang.org/t/magic-incantations-to-make-a-local-module-work/36994 "2020-04-11T06:42:29Z")

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I have some complex code that makes more sense as a module. I have done this before with 2 other “local”–as in in my file system–modules and everything works fine. This one just won’t work. The filename and the module…

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## [Tangent Curves to Linear Functions (Wages and Cobb Douglas)](https://discourse.julialang.org/t/tangent-curves-to-linear-functions-wages-and-cobb-douglas/37377)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 0\
**Last updated:** [April 11, 2020, 3:18am UTC](https://discourse.julialang.org/t/tangent-curves-to-linear-functions-wages-and-cobb-douglas/37377 "2020-04-11T03:18:53Z")

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using Gnuplot, Gaston, Convex, SCS L= 0:600 K=0:600 C=0:600 Q=0:8000 contour(K, L, (K,L)-\>.1\*K^.5\*L^1.5, xlabel="Leisure", ylabel="Consumption",labels=false) #same function as a contour graph for somereason, doesn't r…

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## [Best flux for Tracker: 0.9 or 0.8.3?](https://discourse.julialang.org/t/best-flux-for-tracker-0-9-or-0-8-3/37143)

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**Author:** [@jaynick](https://discourse.julialang.org/u/jaynick)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 3:08am UTC](https://discourse.julialang.org/t/best-flux-for-tracker-0-9-or-0-8-3/37143 "2020-04-11T03:08:31Z")

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A post in this recent discussion recommends using Tracker rather than Zygote if one is less adventurous. I am undecided, but, if one is to use Tracker, which version of Flux is best?

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## [Model Predictive Control (MPC) in Julia](https://discourse.julialang.org/t/model-predictive-control-mpc-in-julia/24240)

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**Author:** [@uwechsler](https://discourse.julialang.org/u/uwechsler)\
**Replies:** 24\
**Last updated:** [April 11, 2020, 3:04am UTC](https://discourse.julialang.org/t/model-predictive-control-mpc-in-julia/24240 "2020-04-11T03:04:16Z")

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I am considering using Julia and JuMP for my Master Thesis in learning based robust economic Model Predictive Control. I hope to get some feedback from the community on what packages to use or on what functionalities are…

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## [Help for improvement for drawing shapefile using Gadfly](https://discourse.julialang.org/t/help-for-improvement-for-drawing-shapefile-using-gadfly/37348)

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**Author:** [@L\_Adam](https://discourse.julialang.org/u/L_Adam)\
**Replies:** 4\
**Last updated:** [April 11, 2020, 2:55am UTC](https://discourse.julialang.org/t/help-for-improvement-for-drawing-shapefile-using-gadfly/37348 "2020-04-11T02:55:46Z")

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I use Shapefile.jl parse \*.shp file into DataFrame, with each row having some region information and a Polygon struct specifies the shape of that region. Everything works smoothly. Big thanks :kissing\_smiling\_eyes: Afte…

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## [Running task on background thread slows performance and increases jitter](https://discourse.julialang.org/t/running-task-on-background-thread-slows-performance-and-increases-jitter/37320)

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**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 2\
**Last updated:** [April 11, 2020, 12:34am UTC](https://discourse.julialang.org/t/running-task-on-background-thread-slows-performance-and-increases-jitter/37320 "2020-04-11T00:34:15Z")

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I’ve been testing to see if Julia is appropriate for recording high volumes of market data arriving over the network with precise timestamps. I ran the simple loop below to simulate parsing strings and to create a littl…

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## [Packages for "my own" code](https://discourse.julialang.org/t/packages-for-my-own-code/27129)

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**Author:** [@hendri54](https://discourse.julialang.org/u/hendri54)\
**Replies:** 21\
**Last updated:** [April 10, 2020, 9:18pm UTC](https://discourse.julialang.org/t/packages-for-my-own-code/27129 "2020-04-10T21:18:23Z")

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I am developing code that I expect will be used only by myself for one or two projects (solving a specific model in economics). This depends on a few modules with reusable code (likely reusable mainly by myself for other…

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## [Flux.functor](https://discourse.julialang.org/t/flux-functor/37334)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 1\
**Last updated:** [April 10, 2020, 8:37pm UTC](https://discourse.julialang.org/t/flux-functor/37334 "2020-04-10T20:37:51Z")

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Could somebody please explain the use of Flux.functor? Functors return functions, but I do not understand the use case. I would also like to understand the use of @functor when using Flux. I tried the following and it w…

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## [Best way to parse custom formatted text file](https://discourse.julialang.org/t/best-way-to-parse-custom-formatted-text-file/37069)

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**Author:** [@jonjilla](https://discourse.julialang.org/u/jonjilla)\
**Replies:** 3\
**Last updated:** [April 10, 2020, 8:13pm UTC](https://discourse.julialang.org/t/best-way-to-parse-custom-formatted-text-file/37069 "2020-04-10T20:13:47Z")

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Hello I’m trying to parse a custom text file. It looks like the CSV.File command works well, but because of the custom nature of the file, that has a lot of extraneous text, I have to first read the file into memory, fi…

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## [Enabling 2FA on major Github orgs](https://discourse.julialang.org/t/enabling-2fa-on-major-github-orgs/31957)

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**Author:** [@viralbshah](https://discourse.julialang.org/u/viralbshah)\
**Replies:** 12\
**Last updated:** [April 10, 2020, 7:29pm UTC](https://discourse.julialang.org/t/enabling-2fa-on-major-github-orgs/31957 "2020-04-10T19:29:01Z")

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I think it would be great for major orgs to turn on 2FA for all org members as general security hygiene. We did this on JuliaLang a while ago, and I enabled it on JuliaPackaging today. I am sure some orgs already do thi…

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## [Problem with grid of plots in StatsPlots](https://discourse.julialang.org/t/problem-with-grid-of-plots-in-statsplots/37362)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 2\
**Last updated:** [April 10, 2020, 7:20pm UTC](https://discourse.julialang.org/t/problem-with-grid-of-plots-in-statsplots/37362 "2020-04-10T19:20:29Z")

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I encountered a problem generating a grid of plots with StatsPlots. Here is a MWE. The x and y ranges are incorrect in the 2nd and 3rd rows: using DataFrames, StatsPlots title = \[string("f1: ",i," ","f2: ",j) for i in…

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