# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1876

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

**Page:** 1877

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## [Really, really big arrays and OutOfMemoryError()](https://discourse.julialang.org/t/really-really-big-arrays-and-outofmemoryerror/31366)

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**Author:** [@clibassi](https://discourse.julialang.org/u/clibassi)\
**Replies:** 6\
**Last updated:** [November 24, 2019, 5:44pm UTC](https://discourse.julialang.org/t/really-really-big-arrays-and-outofmemoryerror/31366 "2019-11-24T17:44:34Z")

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Hi all, I’m a relative newbie to Julia and trying to do some record linkage in Julia. In that process, I need to bring two large datasets (1.8million rows and 800K rows respectively) into an array to loop through and do…

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## [JuMP : Solving an optimisation problem with a large matrix of variables](https://discourse.julialang.org/t/jump-solving-an-optimisation-problem-with-a-large-matrix-of-variables/31347)

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**Author:** [@Wedg](https://discourse.julialang.org/u/Wedg)\
**Replies:** 4\
**Last updated:** [November 24, 2019, 2:08pm UTC](https://discourse.julialang.org/t/jump-solving-an-optimisation-problem-with-a-large-matrix-of-variables/31347 "2019-11-24T14:08:09Z")

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Hi all I have an optimisation of the following form. # Size rows = 6000 cols = 10 # Create model with solver model = Model(with\_optimizer(GLPK.Optimizer)) # Create binary variables @variable(model, X\[1:rows, 1:cols\],…

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## [Help with JSON2.jl](https://discourse.julialang.org/t/help-with-json2-jl/31433)

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**Author:** [@cwiese](https://discourse.julialang.org/u/cwiese)\
**Replies:** 4\
**Last updated:** [November 24, 2019, 1:57pm UTC](https://discourse.julialang.org/t/help-with-json2-jl/31433 "2019-11-24T13:57:33Z")

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What am I doing wrong here? I get ERROR: MethodError: no method matching nQ julia\> mutable struct Q name::String scens::Vector{String} nQ(name, scens) = n…

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## [Setdiff with comparison function?](https://discourse.julialang.org/t/setdiff-with-comparison-function/31405)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 2\
**Last updated:** [November 24, 2019, 7:11am UTC](https://discourse.julialang.org/t/setdiff-with-comparison-function/31405 "2019-11-24T07:11:29Z")

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I need to setdiff between 2 containers using a custom comparison function? Is there such a thing? Thanks

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## [Types for log-domain values](https://discourse.julialang.org/t/types-for-log-domain-values/31394)

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**Author:** [@maxmouchet](https://discourse.julialang.org/u/maxmouchet)\
**Replies:** 12\
**Last updated:** [November 24, 2019, 6:59am UTC](https://discourse.julialang.org/t/types-for-log-domain-values/31394 "2019-11-24T06:59:25Z")

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Hi, I was wondering if there are existing solutions to the following problem. In statistics, it is common to work with likelihoods (positive reals) or log-likelihoods values. Let’s say that we want to implement an alg…

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## [@threads for only using master thread?](https://discourse.julialang.org/t/threads-for-only-using-master-thread/27725)

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**Author:** [@dstarerstor](https://discourse.julialang.org/u/dstarerstor)\
**Replies:** 7\
**Last updated:** [November 24, 2019, 6:43am UTC](https://discourse.julialang.org/t/threads-for-only-using-master-thread/27725 "2019-11-24T06:43:23Z")

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I just switched to 1.3 to try out implementing multithreaded algorithms. I tried a very simple loop, from the announcement post: Threads.@threads for i = 1:10 println(Threads.threadid(), " of ", Threads.nthreads()) e…

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## [Threads.@spawn not using master thread](https://discourse.julialang.org/t/threads-spawn-not-using-master-thread/31442)

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**Author:** [@ignis](https://discourse.julialang.org/u/ignis)\
**Replies:** 2\
**Last updated:** [November 24, 2019, 4:56am UTC](https://discourse.julialang.org/t/threads-spawn-not-using-master-thread/31442 "2019-11-24T04:56:37Z")

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I’ve been using Julia to parallelize some algorithms, so I’m also studying how julia parallel programming works. I did a simple code to check the behavior of Threads.@spawn and I’ve noticed it would only use the master …

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## [Flow Charts? LightGraphs?](https://discourse.julialang.org/t/flow-charts-lightgraphs/31139)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 11\
**Last updated:** [November 24, 2019, 1:34am UTC](https://discourse.julialang.org/t/flow-charts-lightgraphs/31139 "2019-11-24T01:34:35Z")

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How hard would it be to make a quick and dirty wrapper for flow chart plots from DAGs? I gave it a whirl for a jupyter notebook blog I am writing. Didn’t come out so hot! using GraphRecipes using Plots using LightGraph…

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## [\[Senior\] Software engineer position at QuEra in Quantum Computing](https://discourse.julialang.org/t/senior-software-engineer-position-at-quera-in-quantum-computing/31437)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 1\
**Last updated:** [November 24, 2019, 1:27am UTC](https://discourse.julialang.org/t/senior-software-engineer-position-at-quera-in-quantum-computing/31437 "2019-11-24T01:27:31Z")

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Job description: QuEra Computing Inc. is seeking a highly experienced (senior) software engineer to lead the development of a first-of-its-kind software platform for quantum computing, bridging between QuEra’s state-of-t…

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## [How to create executable from julia?](https://discourse.julialang.org/t/how-to-create-executable-from-julia/31422)

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**Author:** [@phaneendra\_muttigi](https://discourse.julialang.org/u/phaneendra_muttigi)\
**Replies:** 2\
**Last updated:** [November 24, 2019, 1:26am UTC](https://discourse.julialang.org/t/how-to-create-executable-from-julia/31422 "2019-11-24T01:26:21Z")

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Packagecompiler instruction are not much clear ,when used the command it just ended up opening in atom editor without any compilation strange. i am almost lost ,can any one help statically compiling Julia scripts.

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## [Using test/Project.toml](https://discourse.julialang.org/t/using-test-project-toml/31406)

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**Author:** [@venuur](https://discourse.julialang.org/u/venuur)\
**Replies:** 4\
**Last updated:** [November 23, 2019, 8:22pm UTC](https://discourse.julialang.org/t/using-test-project-toml/31406 "2019-11-23T20:22:20Z")

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Following the instructions from Pkg docs, I ran the following commands to add two dependecies that I only need for tests: Starting Julia... \_ \_ \_ \_(\_)\_ | Documentation: https://docs.julialan…

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## [Functions inside functions using "global" variables](https://discourse.julialang.org/t/functions-inside-functions-using-global-variables/31434)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 2\
**Last updated:** [November 23, 2019, 11:08pm UTC](https://discourse.julialang.org/t/functions-inside-functions-using-global-variables/31434 "2019-11-23T23:08:23Z")

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Hi! I need help about constructing functions inside functions that use variables that “seems” global: function a() aux = Float64\[\] b = ()-\>begin push!(aux, rand()) end b() b() return aux…

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## [Proper escaping when building a command with nested quotes](https://discourse.julialang.org/t/proper-escaping-when-building-a-command-with-nested-quotes/31432)

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**Author:** [@dapz](https://discourse.julialang.org/u/dapz)\
**Replies:** 0\
**Last updated:** [November 23, 2019, 8:23pm UTC](https://discourse.julialang.org/t/proper-escaping-when-building-a-command-with-nested-quotes/31432 "2019-11-23T20:23:35Z")

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Hi, I was wondering if there is a “rule” to write commands with nested quotes that work. Here is an example with 3 nested commands (bash calling bash calling julia). My final goal is slightly different (a julia call pass…

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## [Regular Expression and Threads](https://discourse.julialang.org/t/regular-expression-and-threads/31415)

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**Author:** [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)\
**Replies:** 3\
**Last updated:** [November 23, 2019, 7:07pm UTC](https://discourse.julialang.org/t/regular-expression-and-threads/31415 "2019-11-23T19:07:11Z")

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Hi All, in our Flux ML project, we need to process large volume of data with a single models. We do it by dividing the minibatch into chunks, calculate gradient on each chunk in a separate thread, and reduce it (is it c…

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## [Robust method of modifying corners of an Array](https://discourse.julialang.org/t/robust-method-of-modifying-corners-of-an-array/31398)

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**Author:** [@jonathan-durbin](https://discourse.julialang.org/u/jonathan-durbin)\
**Replies:** 9\
**Last updated:** [November 23, 2019, 2:37pm UTC](https://discourse.julialang.org/t/robust-method-of-modifying-corners-of-an-array/31398 "2019-11-23T14:37:38Z")

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I’m trying to write a simple function that replaces the corners of an array with a value. This is what I have so far: function replaceCorners!(a::AbstractArray{String, 2}, v::String) a\[1, 1\] = a\[1, size(a)\[2\]\] = a\[s…

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## [Julia v1.3.0-rc5 is now available](https://discourse.julialang.org/t/julia-v1-3-0-rc5-is-now-available/31192)

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**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 15\
**Last updated:** [November 23, 2019, 2:16pm UTC](https://discourse.julialang.org/t/julia-v1-3-0-rc5-is-now-available/31192 "2019-11-23T14:16:51Z")

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The fifth, and I won’t say final this time so as not to jinx it but we really hope final, release candidate for Julia v1.3.0 is now available. You can get binaries at Download Julia for Linux (i686, x86-64, ARMv7, AArch6…

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## [REPL domain error for exponentiation](https://discourse.julialang.org/t/repl-domain-error-for-exponentiation/31408)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 4\
**Last updated:** [November 23, 2019, 1:05pm UTC](https://discourse.julialang.org/t/repl-domain-error-for-exponentiation/31408 "2019-11-23T13:05:19Z")

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Why julia\> 2^-10 0.0009765625 julia\> t = -10 -10 julia\> 2^t ERROR: DomainError with -10: Cannot raise an integer x to a negative power -10. Make x or -10 a float by adding a zero decimal (e.g., 2.0^-10 or 2^-10.0 inst…

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## [Good road network routing packages in julia using .osm data?](https://discourse.julialang.org/t/good-road-network-routing-packages-in-julia-using-osm-data/31417)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 0\
**Last updated:** [November 23, 2019, 12:02pm UTC](https://discourse.julialang.org/t/good-road-network-routing-packages-in-julia-using-osm-data/31417 "2019-11-23T12:02:31Z")

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Hi. I was wondering, is there any good road network routing package in Julia, using .osm data? Any suggestions?

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## [Code execution problem](https://discourse.julialang.org/t/code-execution-problem/31307)

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**Author:** [@dty](https://discourse.julialang.org/u/dty)\
**Replies:** 16\
**Last updated:** [November 23, 2019, 11:06am UTC](https://discourse.julialang.org/t/code-execution-problem/31307 "2019-11-23T11:06:36Z")

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## [Strange Behaviour of Stiff Solvers in DifferentialEquations.jl](https://discourse.julialang.org/t/strange-behaviour-of-stiff-solvers-in-differentialequations-jl/31407)

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**Author:** [@anodos](https://discourse.julialang.org/u/anodos)\
**Replies:** 2\
**Last updated:** [November 23, 2019, 7:50am UTC](https://discourse.julialang.org/t/strange-behaviour-of-stiff-solvers-in-differentialequations-jl/31407 "2019-11-23T07:50:17Z")

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I have run into a surprising problem when using stiff solvers in DifferentialEquations.jl. It appears to be related to the automatic differentiation. Basically, when using the stiff solvers, I appear to be unable to assi…

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## [Macro Question where I can't do the proper substition](https://discourse.julialang.org/t/macro-question-where-i-cant-do-the-proper-substition/31413)

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**Author:** [@Qiyamah](https://discourse.julialang.org/u/Qiyamah)\
**Replies:** 3\
**Last updated:** [November 23, 2019, 7:22am UTC](https://discourse.julialang.org/t/macro-question-where-i-cant-do-the-proper-substition/31413 "2019-11-23T07:22:10Z")

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julia\> macro testy() args=\[:T,:U,:M\] code = :(foreach(a-\>println(typeof(a)),$args)) quote macro qq($(args...)) $code |\>esc end …

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## [Ccall() and libc on Linux](https://discourse.julialang.org/t/ccall-and-libc-on-linux/31402)

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**Author:** [@mleisher](https://discourse.julialang.org/u/mleisher)\
**Replies:** 3\
**Last updated:** [November 22, 2019, 10:28pm UTC](https://discourse.julialang.org/t/ccall-and-libc-on-linux/31402 "2019-11-22T22:28:09Z")

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Trying to use ccall() to call a function from libc and julia only finds the GNU ld script in /usr/lib64/libc.so, not the actual library which is located in /lib64/libc.so.6. Can julia be told to parse the GNU ld script …

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## [JuMP / Ipopt fails at specific parameter ranges](https://discourse.julialang.org/t/jump-ipopt-fails-at-specific-parameter-ranges/31403)

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**Author:** [@paulflang](https://discourse.julialang.org/u/paulflang)\
**Replies:** 0\
**Last updated:** [November 22, 2019, 10:20pm UTC](https://discourse.julialang.org/t/jump-ipopt-fails-at-specific-parameter-ranges/31403 "2019-11-22T22:20:49Z")

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I am new to Julia, trying to fit the parameters of an ODE model using JuMP and Ipopt. The code works as intended in a parameter range of p\_true/fc \<= p \<= fc\*p\_true if fc = 2, 4, or 8. However, fc = 3 or 10 it prints Def…

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## [Dynamic web pages with Interact and Mux](https://discourse.julialang.org/t/dynamic-web-pages-with-interact-and-mux/31360)

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**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 1\
**Last updated:** [November 22, 2019, 9:12pm UTC](https://discourse.julialang.org/t/dynamic-web-pages-with-interact-and-mux/31360 "2019-11-22T21:12:05Z")

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I am trying to write a web GUI controlling some instruments. The basic widgets are working but I’d need to print some variables in real time. MWE follows: using Mux, Interact, CSSUtil s = slider(0:0.01:1, label="Slider"…

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## [JSON to Array of DataFrames](https://discourse.julialang.org/t/json-to-array-of-dataframes/31391)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 4\
**Last updated:** [November 22, 2019, 8:30pm UTC](https://discourse.julialang.org/t/json-to-array-of-dataframes/31391 "2019-11-22T20:30:03Z")

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Hi all- I am trying to store an array of DataFrames as a JSON file and read the JSON file back as the same array of DataFrames. As far as I can tell, the best approach currently is to use JSONTables. Unfortunately, I a…

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## [Scale.y\_continuous percentage format](https://discourse.julialang.org/t/scale-y-continuous-percentage-format/31397)

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**Author:** [@Phillip\_Sutton](https://discourse.julialang.org/u/Phillip_Sutton)\
**Replies:** 4\
**Last updated:** [November 22, 2019, 8:19pm UTC](https://discourse.julialang.org/t/scale-y-continuous-percentage-format/31397 "2019-11-22T20:19:41Z")

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Is there way to format the y axis as percentages in Gadfly? Something like Scale.y\_continuous(format=:percent)

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## [Solving delayed differential equations with Julia](https://discourse.julialang.org/t/solving-delayed-differential-equations-with-julia/30827)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 6\
**Last updated:** [November 22, 2019, 5:26pm UTC](https://discourse.julialang.org/t/solving-delayed-differential-equations-with-julia/30827 "2019-11-22T17:26:01Z")

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Dear all, I would like to solve some delayed differential equations that look like this where t is a fix time and x is a variable time point. I understand that there are specific packages that do this analysis, one …

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## [Package MNIST not found](https://discourse.julialang.org/t/package-mnist-not-found/31352)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 4\
**Last updated:** [November 22, 2019, 5:10pm UTC](https://discourse.julialang.org/t/package-mnist-not-found/31352 "2019-11-22T17:10:51Z")

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Attempting to follow the example on https://fluxml.ai/Flux.jl/v0.2/examples/logreg.html for ‘Simple MNIST’ the package ‘MNIST’ cannot be found using Pkg.add \[ I have spent hours just trying to run the first line of th…

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## [Slow Custom Digits Iterator](https://discourse.julialang.org/t/slow-custom-digits-iterator/31367)

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**Author:** [@jebej](https://discourse.julialang.org/u/jebej)\
**Replies:** 7\
**Last updated:** [November 22, 2019, 4:52pm UTC](https://discourse.julialang.org/t/slow-custom-digits-iterator/31367 "2019-11-22T16:52:38Z")

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I was trying to replace calls to digits, which allocates, with a custom iterator, but for some reason calling sum on it is really slow and allocates, despite e.g. calls to collect being fast: using BenchmarkTools struc…

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## [How to set colours for groups of elements on a plot](https://discourse.julialang.org/t/how-to-set-colours-for-groups-of-elements-on-a-plot/25050)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 5\
**Last updated:** [November 22, 2019, 4:30pm UTC](https://discourse.julialang.org/t/how-to-set-colours-for-groups-of-elements-on-a-plot/25050 "2019-11-22T16:30:15Z")

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I would like to plot the solution for a differential equation, but have certain solutions a specific colour I am using Plot.jl and it currently looks like this I would like to specify that u1(t) to u2(t) are brown, u…

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