# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1698

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

**Page:** 1699

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## [JLD2 MethodError when dealing with large dictionaries?](https://discourse.julialang.org/t/jld2-methoderror-when-dealing-with-large-dictionaries/37234)

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**Author:** [@DocDave](https://discourse.julialang.org/u/DocDave)\
**Replies:** 6\
**Last updated:** [July 4, 2020, 8:40pm UTC](https://discourse.julialang.org/t/jld2-methoderror-when-dealing-with-large-dictionaries/37234 "2020-07-04T20:40:58Z")

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I have a numeric analysis code currently running on a cluster which serialises a dictionary contains several multi-million point arrays using the JLD2 library. The file is saved using @save filename source and read back …

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## [Textslider in Makie](https://discourse.julialang.org/t/textslider-in-makie/42536)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 0\
**Last updated:** [July 4, 2020, 8:10pm UTC](https://discourse.julialang.org/t/textslider-in-makie/42536 "2020-07-04T20:10:17Z")

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I am trying to control the radius of a sphere with a textslider in Makie, using the GeometryTypes module (I know that the module is deprecated, but it should still work.) Based on examples I found online, I wrote the fol…

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## [Flux.jl: Convolutional VAE throws error after upgrading to 1.4.1/10.4](https://discourse.julialang.org/t/flux-jl-convolutional-vae-throws-error-after-upgrading-to-1-4-1-10-4/39746)

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**Author:** [@flo](https://discourse.julialang.org/u/flo)\
**Replies:** 19\
**Last updated:** [July 4, 2020, 7:55pm UTC](https://discourse.julialang.org/t/flux-jl-convolutional-vae-throws-error-after-upgrading-to-1-4-1-10-4/39746 "2020-07-04T19:55:26Z")

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Hello everyone, I am fairly new to Julia and even newer to this forum. I hope, this is the right subforum for my problem. Currently, I am working on a project that involves a Convolutional VAE which I implemented using …

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## [Linear algebra with array wrapper types](https://discourse.julialang.org/t/linear-algebra-with-array-wrapper-types/42483)

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**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 5\
**Last updated:** [July 4, 2020, 5:49pm UTC](https://discourse.julialang.org/t/linear-algebra-with-array-wrapper-types/42483 "2020-07-04T17:49:50Z")

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What is the “correct” way to define multiplication and division for AbstractArray types that are wrappers around other arrays? So let’s say I have an array wrapper type: struct MyArray{T,N,A\<:AbstractArray{T,N}} \<: Abs…

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## [How can I make an Array{Array{Float64,1},1} out of two columns of a dataframe?](https://discourse.julialang.org/t/how-can-i-make-an-array-array-float64-1-1-out-of-two-columns-of-a-dataframe/42489)

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**Author:** [@gedankenexperiment](https://discourse.julialang.org/u/gedankenexperiment)\
**Replies:** 6\
**Last updated:** [July 4, 2020, 4:58pm UTC](https://discourse.julialang.org/t/how-can-i-make-an-array-array-float64-1-1-out-of-two-columns-of-a-dataframe/42489 "2020-07-04T16:58:56Z")

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I have a dataframe with two columns x,y of type Float. I want to apply the concave\_hull() function of the ConcaveHull package on those columns. But it prefers a \[\[1.0,2.0\],\[3.0,4.0\],...\] object. How can I now convert the…

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## [MethodError: Cannot \`convert\` an object of type Array{Float64,1} to an object of type Float64](https://discourse.julialang.org/t/methoderror-cannot-convert-an-object-of-type-array-float64-1-to-an-object-of-type-float64/42527)

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**Author:** [@hafez\_ahmad](https://discourse.julialang.org/u/hafez_ahmad)\
**Replies:** 7\
**Last updated:** [July 4, 2020, 4:53pm UTC](https://discourse.julialang.org/t/methoderror-cannot-convert-an-object-of-type-array-float64-1-to-an-object-of-type-float64/42527 "2020-07-04T16:53:13Z")

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‘’’ I am using julia 1.4.2 nx = 60 ; # try changing this number from 41 to 81 and Run All ... what happens? dx = 2/(nx-1); nt = 25 ; #nt is the number of timesteps we want to calculate dt = .025 ; #dt is the amount o…

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## [What's the best way to dispatch on an \_iterable\_ trait?](https://discourse.julialang.org/t/whats-the-best-way-to-dispatch-on-an-iterable-trait/42084)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 15\
**Last updated:** [July 4, 2020, 3:38pm UTC](https://discourse.julialang.org/t/whats-the-best-way-to-dispatch-on-an-iterable-trait/42084 "2020-07-04T15:38:30Z")

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I find that it’s quite common for me to write a function that requires the input to be iterable. But I don’t think there is a good way to restrict it to that. I think I would love to see a trait system built into Julia e…

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## [Julia vs. R Speed for sampling the Wishart distribution](https://discourse.julialang.org/t/julia-vs-r-speed-for-sampling-the-wishart-distribution/21352)

<div class="topic-metadata">

**Author:** [@Donald\_Williams](https://discourse.julialang.org/u/Donald_Williams)\
**Replies:** 28\
**Last updated:** [July 4, 2020, 2:50pm UTC](https://discourse.julialang.org/t/julia-vs-r-speed-for-sampling-the-wishart-distribution/21352 "2020-07-04T14:50:10Z")

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Hi: I was wondering if it is possible to speed up the following. I have found it takes much longer than R. The difference is not small, as in Julia this take 11 seconds and in R it takes only 1.5 seconds. function …

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## [Using a function without defining it in the code, but placing it in the current directory](https://discourse.julialang.org/t/using-a-function-without-defining-it-in-the-code-but-placing-it-in-the-current-directory/42520)

<div class="topic-metadata">

**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 2\
**Last updated:** [July 4, 2020, 1:19pm UTC](https://discourse.julialang.org/t/using-a-function-without-defining-it-in-the-code-but-placing-it-in-the-current-directory/42520 "2020-07-04T13:19:55Z")

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Functions in MATLAB can be saved in the current directory and called without explicitly defining them again in the current code. Is that possible in Julia?

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## [Flux.jl: Error thrown during gradient calculation in conv VAE](https://discourse.julialang.org/t/flux-jl-error-thrown-during-gradient-calculation-in-conv-vae/42397)

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**Author:** [@alecokas](https://discourse.julialang.org/u/alecokas)\
**Replies:** 4\
**Last updated:** [July 4, 2020, 12:18pm UTC](https://discourse.julialang.org/t/flux-jl-error-thrown-during-gradient-calculation-in-conv-vae/42397 "2020-07-04T12:18:01Z")

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Hi, I’m just getting into Flux (and Julia more generally), but I’m finding it impossible to get rid of a very particular error in my convolutional VAE model. The code runs fine until the back(1f0) line where it throws E…

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## [Adding methods with metaprogramming](https://discourse.julialang.org/t/adding-methods-with-metaprogramming/42518)

<div class="topic-metadata">

**Author:** [@sw72](https://discourse.julialang.org/u/sw72)\
**Replies:** 1\
**Last updated:** [July 4, 2020, 11:58am UTC](https://discourse.julialang.org/t/adding-methods-with-metaprogramming/42518 "2020-07-04T11:58:12Z")

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I have a couple of types defined like this: struct Foo foo end struct Bar foo::Foo bar baz end Then I have a bunch of functions defined for Foo, with additional methods for Bar that just pass through t…

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## [Alternate BLAS libraries?](https://discourse.julialang.org/t/alternate-blas-libraries/26317)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 22\
**Last updated:** [July 4, 2020, 11:23am UTC](https://discourse.julialang.org/t/alternate-blas-libraries/26317 "2020-07-04T11:23:20Z")

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I’m running some processor heavy stochastic simulations that are increasingly limited by BLAS matrix dot multiplications on 9\*9 matrices, as I gradually add optimisations for everything else. It seems that MKL (and mayb…

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## [ImageMagick.jl and PyPlot.jl conflicting libpng](https://discourse.julialang.org/t/imagemagick-jl-and-pyplot-jl-conflicting-libpng/37139)

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**Author:** [@goretkin](https://discourse.julialang.org/u/goretkin)\
**Replies:** 3\
**Last updated:** [July 4, 2020, 10:46am UTC](https://discourse.julialang.org/t/imagemagick-jl-and-pyplot-jl-conflicting-libpng/37139 "2020-07-04T10:46:25Z")

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on my macOS machine, I can trigger this with julia\> import ImageMagick julia\> import PyCall; PyCall.pyimport("matplotlib") gives ImportError('dlopen(/Users/goretkin/.julia/conda/3/lib/python3.7/site-packages/matplotl…

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## [How does one add rows to a Julia array?](https://discourse.julialang.org/t/how-does-one-add-rows-to-a-julia-array/24056)

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**Author:** [@Elmer\_Cusipuma](https://discourse.julialang.org/u/Elmer_Cusipuma)\
**Replies:** 6\
**Last updated:** [July 4, 2020, 9:54am UTC](https://discourse.julialang.org/t/how-does-one-add-rows-to-a-julia-array/24056 "2020-07-04T09:54:05Z")

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I have an empty array A: A = Array{Float64}(undef, 0, 2) and a vector that I want to add: m = rand(2) I try to do this: A = \[A;m\] ArgumentError: number of columns of each array must match (got (2, 1)) Thanks.

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## [Sklearn (scikit learn) alternative?](https://discourse.julialang.org/t/sklearn-scikit-learn-alternative/42512)

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**Author:** [@hafez\_ahmad](https://discourse.julialang.org/u/hafez_ahmad)\
**Replies:** 2\
**Last updated:** [July 4, 2020, 8:20am UTC](https://discourse.julialang.org/t/sklearn-scikit-learn-alternative/42512 "2020-07-04T08:20:05Z")

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is there any alternative of the scikit learn in pure Julia? I think, sci-kit learn is help in python and I found the most popular and useful algorithms. can I get the same Julia package? any help appreciated

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## [No gradient is calculated during Flux training with ODE](https://discourse.julialang.org/t/no-gradient-is-calculated-during-flux-training-with-ode/42455)

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**Author:** [@yanz4](https://discourse.julialang.org/u/yanz4)\
**Replies:** 1\
**Last updated:** [July 4, 2020, 7:37am UTC](https://discourse.julialang.org/t/no-gradient-is-calculated-during-flux-training-with-ode/42455 "2020-07-04T07:37:18Z")

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I tried to update the parameters in ODE by Flux training. In Struct V203, only 2 parameters are selected to be tracked for backpropagation: Flux.trainable(device::V2O3) = (device.Rth, device.Cth) During training, these …

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## [Request to be deleted](https://discourse.julialang.org/t/request-to-be-deleted/42504)

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**Author:** [@yanz4](https://discourse.julialang.org/u/yanz4)\
**Replies:** 4\
**Last updated:** [July 4, 2020, 3:36am UTC](https://discourse.julialang.org/t/request-to-be-deleted/42504 "2020-07-04T03:36:04Z")

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I’m building an oscillator (called V2O3) defined by ODE (V2O3\_system as named in code below). The purpose is to use Flux training to optimize parameters in ODE, i.e. the R and C value of the oscillator, given loss funct…

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## [How to make a function recognize datatype argument](https://discourse.julialang.org/t/how-to-make-a-function-recognize-datatype-argument/42499)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 2\
**Last updated:** [July 3, 2020, 11:47pm UTC](https://discourse.julialang.org/t/how-to-make-a-function-recognize-datatype-argument/42499 "2020-07-03T23:47:02Z")

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Here is a function that is supposed to turn a vector of strings to an Array{Union{Missing,Int64}: function NAtoMissing(data::Array{Any,1},nonmissing::DataType,tomissing::Any) withmissing = Array{Union{Missing, nonmi…

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## [Optimization problem with Julia - Launch sequence](https://discourse.julialang.org/t/optimization-problem-with-julia-launch-sequence/42311)

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**Author:** [@beske](https://discourse.julialang.org/u/beske)\
**Replies:** 14\
**Last updated:** [July 3, 2020, 11:01pm UTC](https://discourse.julialang.org/t/optimization-problem-with-julia-launch-sequence/42311 "2020-07-03T23:01:58Z")

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Say you have n different shops in which you want to launch a product for n different months, and you want to maximize profits. The problem is determining the order of the launch sequence of the product when the price in …

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## [Broadcast into higher dimensional array vs nested array](https://discourse.julialang.org/t/broadcast-into-higher-dimensional-array-vs-nested-array/42454)

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**Author:** [@kschurter](https://discourse.julialang.org/u/kschurter)\
**Replies:** 4\
**Last updated:** [July 3, 2020, 10:26pm UTC](https://discourse.julialang.org/t/broadcast-into-higher-dimensional-array-vs-nested-array/42454 "2020-07-03T22:26:48Z")

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I want to broadcast a vector-valued function and store the results in a higher dimensional array as opposed to a vector of arrays. I like the performance of this code: import .Base: Broadcast import .Broadcast: Broadcas…

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## [Trying to read netCDF4 file with NetCDF.jl](https://discourse.julialang.org/t/trying-to-read-netcdf4-file-with-netcdf-jl/42497)

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**Author:** [@renato](https://discourse.julialang.org/u/renato)\
**Replies:** 2\
**Last updated:** [July 3, 2020, 9:40pm UTC](https://discourse.julialang.org/t/trying-to-read-netcdf4-file-with-netcdf-jl/42497 "2020-07-03T21:40:30Z")

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Hello! Trying to read a NetCDF4 file, using NetCDF.jl, and although I can read it in Python with netCDF4 package (so I conclude the file is ok), in Julia I can’t even get general information with ncinfo(filename), as my…

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## [Iterating over 2D array and placing results in 1D array with the same number of elements](https://discourse.julialang.org/t/iterating-over-2d-array-and-placing-results-in-1d-array-with-the-same-number-of-elements/42403)

<div class="topic-metadata">

**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 20\
**Last updated:** [July 3, 2020, 10:05pm UTC](https://discourse.julialang.org/t/iterating-over-2d-array-and-placing-results-in-1d-array-with-the-same-number-of-elements/42403 "2020-07-03T22:05:32Z")

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I have: a = rand(Float32, h\*w) b = reshape(a, h, w) c = similar(a) I would like to iterate over array b, calculate a result based on element value and its 2D coordinates and put it in c. The order of elements in c is i…

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## [Using complements in JuMP](https://discourse.julialang.org/t/using-complements-in-jump/42486)

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**Author:** [@jovansam](https://discourse.julialang.org/u/jovansam)\
**Replies:** 5\
**Last updated:** [July 3, 2020, 6:47pm UTC](https://discourse.julialang.org/t/using-complements-in-jump/42486 "2020-07-03T18:47:03Z")

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I am trying to use complements in Julia-JuMP. I appreciate the work put into this wonderful package, the manual is not detailed enough unfortunately. A working example that uses this feature in an optimization problem w…

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## [Use of methods()](https://discourse.julialang.org/t/use-of-methods/42478)

<div class="topic-metadata">

**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 10\
**Last updated:** [July 3, 2020, 8:10pm UTC](https://discourse.julialang.org/t/use-of-methods/42478 "2020-07-03T20:10:05Z")

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I would like to understand the use of methods(function, types). Consider the following two invocations, whose results are not the same. This implies that the order in which the types are listed in the second argument imp…

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## [Error involving MvNormal(::Array{Float64,2}) repeating?](https://discourse.julialang.org/t/error-involving-mvnormal-array-float64-2-repeating/42393)

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**Author:** [@samd1993](https://discourse.julialang.org/u/samd1993)\
**Replies:** 4\
**Last updated:** [July 3, 2020, 7:35pm UTC](https://discourse.julialang.org/t/error-involving-mvnormal-array-float64-2-repeating/42393 "2020-07-03T19:35:05Z")

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Hi all, I am trying to run something in Julia and keep getting the same error. Here is the code and output: (base) \[sdegregori@surfingmantis mimix\]$ mkdir simulation-results julia (base) \[sdegregori@surfingmantis mimix…

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## [How do I define a function whose argument is iterable?](https://discourse.julialang.org/t/how-do-i-define-a-function-whose-argument-is-iterable/42484)

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**Author:** [@SatyaKomatineni](https://discourse.julialang.org/u/SatyaKomatineni)\
**Replies:** 5\
**Last updated:** [July 3, 2020, 6:19pm UTC](https://discourse.julialang.org/t/how-do-i-define-a-function-whose-argument-is-iterable/42484 "2020-07-03T18:19:33Z")

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function printItems(iter) #print or do something with each item end How do I say “iter” is of type that can be iterated on? I don’t want to say for example AbstractArray because anything iteratable will work. Note: I…

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## [Objective function error](https://discourse.julialang.org/t/objective-function-error/42482)

<div class="topic-metadata">

**Author:** [@RaquelSantos](https://discourse.julialang.org/u/RaquelSantos)\
**Replies:** 2\
**Last updated:** [July 3, 2020, 6:18pm UTC](https://discourse.julialang.org/t/objective-function-error/42482 "2020-07-03T18:18:41Z")

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I need to reproduce that model. using JuMP, Cbc Model1 = Model(with\_optimizer(Cbc.Optimizer)) a = 2 t = 2 w = 2 A = 1:a T = 1:t W = 1:w CR = \[11, 11\] @variable(Model1,r\[A,T\], lower\_bound=0) @variable(Model1,o\[A…

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## [Finding the index where the values in one array are greater than the values in another array](https://discourse.julialang.org/t/finding-the-index-where-the-values-in-one-array-are-greater-than-the-values-in-another-array/42485)

<div class="topic-metadata">

**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 2\
**Last updated:** [July 3, 2020, 5:58pm UTC](https://discourse.julialang.org/t/finding-the-index-where-the-values-in-one-array-are-greater-than-the-values-in-another-array/42485 "2020-07-03T17:58:19Z")

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I need to find the index of all instances where the values in one array (A, say) is larger than the corresponding values in another array (B, say, with B having the same length as A). What is the best practice way to so…

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## [Understanding Julia docs: Where is Base.Regex type documented?](https://discourse.julialang.org/t/understanding-julia-docs-where-is-base-regex-type-documented/42481)

<div class="topic-metadata">

**Author:** [@SatyaKomatineni](https://discourse.julialang.org/u/SatyaKomatineni)\
**Replies:** 2\
**Last updated:** [July 3, 2020, 5:39pm UTC](https://discourse.julialang.org/t/understanding-julia-docs-where-is-base-regex-type-documented/42481 "2020-07-03T17:39:21Z")

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Beginner. I was hoping to find docs for Base.Regex type and its constructor in the “Base” module. However I find it here https://docs.julialang.org/en/v1/base/strings/#Base.@r\_str Even that in a “strings” topic. Bro…

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## [\[ANN\] ContextTracking.jl - writing context-aware applications](https://discourse.julialang.org/t/ann-contexttracking-jl-writing-context-aware-applications/42462)

<div class="topic-metadata">

**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 4\
**Last updated:** [July 3, 2020, 4:09pm UTC](https://discourse.julialang.org/t/ann-contexttracking-jl-writing-context-aware-applications/42462 "2020-07-03T16:09:12Z")

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Hi everyone, Today, I would like to announce ContextTracking.jl, a package that helps you keep track of contextual information during program execution. A quick example Suppose that you have 4 functions: A calls B, B c…

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