# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1686

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

**Page:** 1687

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## [Worse Performance with Approximate Minimum Degree Reordering of Sparse Matrices + LU Than \`\\\`?](https://discourse.julialang.org/t/worse-performance-with-approximate-minimum-degree-reordering-of-sparse-matrices-lu-than/43212)

<div class="topic-metadata">

**Author:** [@jchen975](https://discourse.julialang.org/u/jchen975)\
**Replies:** 4\
**Last updated:** [July 18, 2020, 12:17am UTC](https://discourse.julialang.org/t/worse-performance-with-approximate-minimum-degree-reordering-of-sparse-matrices-lu-than/43212 "2020-07-18T00:17:43Z")

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I’m trying to test the supposed boost in performance (as seen from Matlab) when AMD reordering is used before factorization with the lu when solving Ax = b, where A is a real valued n \\times n sparse matrix. Here is my…

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## [Adjoint of Matrix is not a StridedArray?](https://discourse.julialang.org/t/adjoint-of-matrix-is-not-a-stridedarray/43038)

<div class="topic-metadata">

**Author:** [@SEA](https://discourse.julialang.org/u/SEA)\
**Replies:** 3\
**Last updated:** [July 17, 2020, 11:06pm UTC](https://discourse.julialang.org/t/adjoint-of-matrix-is-not-a-stridedarray/43038 "2020-07-17T23:06:02Z")

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I am implementing a linear algebra routine for which I am trying to reuse an allocated array, but need to reshape it and take transposes of it. In this process, I noticed that no method exists for ldiv!(::LU, Adjoint{Fl…

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## [Best generic method to solve homogeneous system](https://discourse.julialang.org/t/best-generic-method-to-solve-homogeneous-system/43261)

<div class="topic-metadata">

**Author:** [@jebej](https://discourse.julialang.org/u/jebej)\
**Replies:** 3\
**Last updated:** [July 17, 2020, 10:35pm UTC](https://discourse.julialang.org/t/best-generic-method-to-solve-homogeneous-system/43261 "2020-07-17T22:35:51Z")

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What is the best way to solve the homogeneous system A\\vec{x}=\\vec{0} for either a dense or sparse array (or even GPU array)? For dense A, nullspace(A) works, and for a sparse array, eigs(A,nev=1,which=:SM) appears to w…

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## [Reduce vs. foldl: performance and precision](https://discourse.julialang.org/t/reduce-vs-foldl-performance-and-precision/43231)

<div class="topic-metadata">

**Author:** [@Boo](https://discourse.julialang.org/u/Boo)\
**Replies:** 11\
**Last updated:** [July 17, 2020, 9:44pm UTC](https://discourse.julialang.org/t/reduce-vs-foldl-performance-and-precision/43231 "2020-07-17T21:44:35Z")

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Hi guys, Can you explain me, please, the difference in performance and precision between reduce and foldl? julia\> using BenchmarkTools julia\> a = rand(10^7) 10000000-element Array{Float64,1}: 0.8488959437260439 0.76…

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## [Any attempt to use Pkg turns into failure](https://discourse.julialang.org/t/any-attempt-to-use-pkg-turns-into-failure/43222)

<div class="topic-metadata">

**Author:** [@Berz\_Qwer](https://discourse.julialang.org/u/Berz_Qwer)\
**Replies:** 3\
**Last updated:** [July 17, 2020, 3:00pm UTC](https://discourse.julialang.org/t/any-attempt-to-use-pkg-turns-into-failure/43222 "2020-07-17T15:00:23Z")

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ERROR: Plots=91a5bcdd-55d7-5caf-9e0b-520d859cae80 depends on Pkg=44cfe95a-1eb2-52ea-b672-e2afdf69b78f, but entry with UUID 44cfe95a-1eb2-52ea-b672-e2afdf69b78f has name Pkg-93b6d6de857dc88e665d2c64397852ab9701ba24. Stac…

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## [\[ANN\] Announcing Torch.jl](https://discourse.julialang.org/t/ann-announcing-torch-jl/42390)

<div class="topic-metadata">

**Author:** [@dhairyagandhi96](https://discourse.julialang.org/u/dhairyagandhi96)\
**Replies:** 14\
**Last updated:** [July 17, 2020, 6:59pm UTC](https://discourse.julialang.org/t/ann-announcing-torch-jl/42390 "2020-07-17T18:59:14Z")

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I am excited to share some new development in the Julia ML stack. We are announcing Torch.jl which wraps the existing PyTorch and its CUDA kernels and makes them available through Julia. Torch.jl also exposes the kernels…

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## [Redirecting stdout to avoid banners while \`import\`ing](https://discourse.julialang.org/t/redirecting-stdout-to-avoid-banners-while-import-ing/37633)

<div class="topic-metadata">

**Author:** [@abulak](https://discourse.julialang.org/u/abulak)\
**Replies:** 12\
**Last updated:** [July 17, 2020, 6:31pm UTC](https://discourse.julialang.org/t/redirecting-stdout-to-avoid-banners-while-import-ing/37633 "2020-07-17T18:31:23Z")

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I have a silly problem: We’re using a few packages that insist on printing their banners upon importing (consider this as something beyond me:). This results in a “barrage of banners” situation. I tried to redirect out…

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## [Projecting Histograms in 3D](https://discourse.julialang.org/t/projecting-histograms-in-3d/43149)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 6\
**Last updated:** [July 17, 2020, 5:42pm UTC](https://discourse.julialang.org/t/projecting-histograms-in-3d/43149 "2020-07-17T17:42:56Z")

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Is it possible to make a plot like this in Julia? I’ve looked into plot3d, but I can’t get histograms to work with it.

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## [Dependent mass matrix with RadauIIA5](https://discourse.julialang.org/t/dependent-mass-matrix-with-radauiia5/43189)

<div class="topic-metadata">

**Author:** [@Jorge\_Silva](https://discourse.julialang.org/u/Jorge_Silva)\
**Replies:** 4\
**Last updated:** [July 17, 2020, 5:28pm UTC](https://discourse.julialang.org/t/dependent-mass-matrix-with-radauiia5/43189 "2020-07-17T17:28:48Z")

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When running this code Im obtaing not expect not smooth solutions. using Plots using DifferentialEquations Ta=20.0+273.15; ka=1.5207e-11\*Ta^3 - 4.…

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## [Matrix in SymbolicUtils?](https://discourse.julialang.org/t/matrix-in-symbolicutils/43229)

<div class="topic-metadata">

**Author:** [@tomtom](https://discourse.julialang.org/u/tomtom)\
**Replies:** 18\
**Last updated:** [July 17, 2020, 4:40pm UTC](https://discourse.julialang.org/t/matrix-in-symbolicutils/43229 "2020-07-17T16:40:25Z")

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how could I create, say a 2x2, symbolic matrix using SymbolicUtils? e.g. something like \[a11 a12; a21 a22\] where aij are symbols… I cannot find in the manual… also, could I create a single symbol for a matrix e.g. m, an…

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## [Converting a string into a string of zeroes and ones on basis of some test](https://discourse.julialang.org/t/converting-a-string-into-a-string-of-zeroes-and-ones-on-basis-of-some-test/43243)

<div class="topic-metadata">

**Author:** [@JaydevSR](https://discourse.julialang.org/u/JaydevSR)\
**Replies:** 6\
**Last updated:** [July 17, 2020, 4:04pm UTC](https://discourse.julialang.org/t/converting-a-string-into-a-string-of-zeroes-and-ones-on-basis-of-some-test/43243 "2020-07-17T16:04:52Z")

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Is there a way to convert a string into zeroes and ones on the basis of some test like follows?: vowels = \['a', 'e', 'i', 'o', 'u'\] string = "string" bits = my\_fun(i -\> (i in vowels), string) #returns "000100" Here I n…

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## [Question about clustering visualization](https://discourse.julialang.org/t/question-about-clustering-visualization/43240)

<div class="topic-metadata">

**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 1\
**Last updated:** [July 17, 2020, 3:32pm UTC](https://discourse.julialang.org/t/question-about-clustering-visualization/43240 "2020-07-17T15:32:43Z")

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Can anyone introduce some good Pkg for clustering visualization?(T-sne seems to have stopped updating) thank you!!!

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## [\[ANN\]: An efficient and scalable ecosystem for robot learning](https://discourse.julialang.org/t/ann-an-efficient-and-scalable-ecosystem-for-robot-learning/33730)

<div class="topic-metadata">

**Author:** [@colinxs](https://discourse.julialang.org/u/colinxs)\
**Replies:** 4\
**Last updated:** [July 17, 2020, 3:21pm UTC](https://discourse.julialang.org/t/ann-an-efficient-and-scalable-ecosystem-for-robot-learning/33730 "2020-07-17T15:21:49Z")

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Welcome to Lyceum, a framework for developing reinforcement learning, trajectory optimization, and other algorithms for continuous control problems in Julia. The primary goal of Lyceum is to increase research throughput …

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## [Calling a function with variable numbers of parameters using an array](https://discourse.julialang.org/t/calling-a-function-with-variable-numbers-of-parameters-using-an-array/43235)

<div class="topic-metadata">

**Author:** [@grahamstark](https://discourse.julialang.org/u/grahamstark)\
**Replies:** 3\
**Last updated:** [July 17, 2020, 1:53pm UTC](https://discourse.julialang.org/t/calling-a-function-with-variable-numbers-of-parameters-using-an-array/43235 "2020-07-17T13:53:10Z")

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There is a function I want to call that accepts a variable number of parameters of a given type. If I have an array of objects of that type (or some other collection), is there some trick I can use to just pass the colle…

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## [Call Intel MKL as external library](https://discourse.julialang.org/t/call-intel-mkl-as-external-library/2097)

<div class="topic-metadata">

**Author:** [@Tecnezio](https://discourse.julialang.org/u/Tecnezio)\
**Replies:** 6\
**Last updated:** [July 17, 2020, 1:52pm UTC](https://discourse.julialang.org/t/call-intel-mkl-as-external-library/2097 "2020-07-17T13:52:42Z")

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I wrote a script to test a call to Intel MKL a external library but it doesn’t work. The concept: Solve a linear system using MKL “dgetrs” (Documentation Library) # Test MKL solve linear systems N = 10; A = rand(N,N)…

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## [How do I not skip missing values when using stack / unstack for pivot tables](https://discourse.julialang.org/t/how-do-i-not-skip-missing-values-when-using-stack-unstack-for-pivot-tables/43238)

<div class="topic-metadata">

**Author:** [@Julia1](https://discourse.julialang.org/u/Julia1)\
**Replies:** 2\
**Last updated:** [July 17, 2020, 1:26pm UTC](https://discourse.julialang.org/t/how-do-i-not-skip-missing-values-when-using-stack-unstack-for-pivot-tables/43238 "2020-07-17T13:26:22Z")

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Hi how’s it going, Here’s an example to better explain what I mean: df = DataFrame(:user=\>\["bob","bob","phil","phil"\],:count=\>\["one","two","two",missing\]) var1 = :user var2 = :count long\_df = by(df,\[var1,var2\],var2=\>l…

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## [Using push!() on an array with 'nothing' as its only value results in error](https://discourse.julialang.org/t/using-push-on-an-array-with-nothing-as-its-only-value-results-in-error/43188)

<div class="topic-metadata">

**Author:** [@JaydevSR](https://discourse.julialang.org/u/JaydevSR)\
**Replies:** 10\
**Last updated:** [July 17, 2020, 12:56pm UTC](https://discourse.julialang.org/t/using-push-on-an-array-with-nothing-as-its-only-value-results-in-error/43188 "2020-07-17T12:56:10Z")

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I was trying to implement a stack using an array for which I had to create a single value array \[nothing\]. I needed nothing because my code included peeking the array. But when I tried to push an integer value into the a…

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## [Qr of custom number type works but svd fails to find a method](https://discourse.julialang.org/t/qr-of-custom-number-type-works-but-svd-fails-to-find-a-method/43226)

<div class="topic-metadata">

**Author:** [@tomohiro\_soejima](https://discourse.julialang.org/u/tomohiro_soejima)\
**Replies:** 2\
**Last updated:** [July 17, 2020, 12:08pm UTC](https://discourse.julialang.org/t/qr-of-custom-number-type-works-but-svd-fails-to-find-a-method/43226 "2020-07-17T12:08:06Z")

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Hi, I’ve been playing around with implementing MyQuaternion type to demonstrate versatility of Julia’s type system to newcomers. I managed to get QR to work, but svd fails for some reason. Here is my implementation: us…

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## [\[ANN\]: GeoStats.jl v0.14](https://discourse.julialang.org/t/ann-geostats-jl-v0-14/43230)

<div class="topic-metadata">

**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 0\
**Last updated:** [July 17, 2020, 12:07pm UTC](https://discourse.julialang.org/t/ann-geostats-jl-v0-14/43230 "2020-07-17T12:07:40Z")

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Dear geospatial community, I am very happy to announce a quite exciting release of GeoStats.jl! In this release, we’ve introduced a cleaner, unified approach to georeferencing data (e.g. tables and arrays). To demonstra…

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## [VSCode showing "Possible method call error" for working code](https://discourse.julialang.org/t/vscode-showing-possible-method-call-error-for-working-code/43219)

<div class="topic-metadata">

**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 2\
**Last updated:** [July 17, 2020, 9:20am UTC](https://discourse.julialang.org/t/vscode-showing-possible-method-call-error-for-working-code/43219 "2020-07-17T09:20:38Z")

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Hi, I’m in the process of writing a package for scraping a particular API (see here) and I am getting “Possible method call error” for two types of calls. The first is when calling parse from the JSON package (the API …

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## [Julia Vscode new version issue with JuMP](https://discourse.julialang.org/t/julia-vscode-new-version-issue-with-jump/43134)

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**Author:** [@afazevedo](https://discourse.julialang.org/u/afazevedo)\
**Replies:** 4\
**Last updated:** [July 17, 2020, 10:35am UTC](https://discourse.julialang.org/t/julia-vscode-new-version-issue-with-jump/43134 "2020-07-17T10:35:05Z")

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I’m having a problem with SparsesAxisArray JuMP on Julia for Vscode. When I use @variable with this condition below, it reproduces an error using Gurobi, JuMP model = Model(Gurobi.Optimizer) n = 5 V = 1:n V0= 1:n+…

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## [Code giving wrong answer for Advent of Code 2015 day 6](https://discourse.julialang.org/t/code-giving-wrong-answer-for-advent-of-code-2015-day-6/43194)

<div class="topic-metadata">

**Author:** [@Sanji\_Vinsmoke](https://discourse.julialang.org/u/Sanji_Vinsmoke)\
**Replies:** 2\
**Last updated:** [July 17, 2020, 8:52am UTC](https://discourse.julialang.org/t/code-giving-wrong-answer-for-advent-of-code-2015-day-6/43194 "2020-07-17T08:52:07Z")

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I was trying to write a solution to Advent of Code 2015 day 6 and I am getting a wring answer. Can someone please help whats going wrong. function solve() path = pwd() \* "/AoC/input.txt" instructions = readline…

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## [A package/example for a simple neural network?](https://discourse.julialang.org/t/a-package-example-for-a-simple-neural-network/43007)

<div class="topic-metadata">

**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 4\
**Last updated:** [July 17, 2020, 8:41am UTC](https://discourse.julialang.org/t/a-package-example-for-a-simple-neural-network/43007 "2020-07-17T08:41:06Z")

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I try to find an easy-to-use package or example for training a forward-feed single-layer neural network. In R, the neuralnet and nnet packages are easy to use for a layman like me. But, I couldn’t find an equivalent pack…

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## [Passing symbol values using \`@everywhere\`?](https://discourse.julialang.org/t/passing-symbol-values-using-everywhere/43178)

<div class="topic-metadata">

**Author:** [@haberdashPI](https://discourse.julialang.org/u/haberdashPI)\
**Replies:** 3\
**Last updated:** [July 16, 2020, 9:05pm UTC](https://discourse.julialang.org/t/passing-symbol-values-using-everywhere/43178 "2020-07-16T21:05:19Z")

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This seems like a bug: julia\> using Distributed; addprocs() julia\> classifier = :logistic\_l1 julia\> @everywhere classifier = $classifier ERROR: On worker 2: UndefVarError: logistic\_l1 not defined top-level scope at none…

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## [Help with ForwardDiff2](https://discourse.julialang.org/t/help-with-forwarddiff2/38384)

<div class="topic-metadata">

**Author:** [@francesco.alemanno](https://discourse.julialang.org/u/francesco.alemanno)\
**Replies:** 1\
**Last updated:** [July 17, 2020, 7:57am UTC](https://discourse.julialang.org/t/help-with-forwarddiff2/38384 "2020-07-17T07:57:28Z")

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I cant’s seem to make this kind of code work with ForwardDiff2 function gaussian(f,N) a=-8.38149 # exp(-x^2/2)/sqrt(2π) == eps(1.0) b=8.38149 dx=(b-a)/(N) Δ=(b-a)/(2N) x=a+Δ I=(exp(-x\*x/2).\*f(x)…

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## [Memory allocations when converting from NamedTuples to DataFrame](https://discourse.julialang.org/t/memory-allocations-when-converting-from-namedtuples-to-dataframe/43171)

<div class="topic-metadata">

**Author:** [@miromarszal](https://discourse.julialang.org/u/miromarszal)\
**Replies:** 4\
**Last updated:** [July 17, 2020, 7:37am UTC](https://discourse.julialang.org/t/memory-allocations-when-converting-from-namedtuples-to-dataframe/43171 "2020-07-17T07:37:44Z")

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I have been struggling with this since a while. When I’m trying to convert an Array of NamedTuple to DataFrame, I’m seeing excessive memory allocations. Consider the following stripped-down example: using DataFrames usi…

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## [Best practice for packaging python package in a Julia package](https://discourse.julialang.org/t/best-practice-for-packaging-python-package-in-a-julia-package/43217)

<div class="topic-metadata">

**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [July 17, 2020, 7:20am UTC](https://discourse.julialang.org/t/best-practice-for-packaging-python-package-in-a-julia-package/43217 "2020-07-17T07:20:58Z")

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I saw this https://github.com/JuliaML/OpenAIGym.jl/issues/42 So that got me thinking, what’s the best to package Python packages for Julia? What if these PYthon packages contain binaries? If there a way to use BinaryBui…

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## [Simple keyboard interaction with Makie visualization](https://discourse.julialang.org/t/simple-keyboard-interaction-with-makie-visualization/43215)

<div class="topic-metadata">

**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 0\
**Last updated:** [July 17, 2020, 6:48am UTC](https://discourse.julialang.org/t/simple-keyboard-interaction-with-makie-visualization/43215 "2020-07-17T06:48:59Z")

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I want to visualize 2D/3D output of some function with different arguments depending on simple keyboard input: a key pressed produces new output for visualization. Here is a simple example: using Makie let npoints = …

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## [ArchGDAL - memory issue with vector data](https://discourse.julialang.org/t/archgdal-memory-issue-with-vector-data/42827)

<div class="topic-metadata">

**Author:** [@julien\_goo](https://discourse.julialang.org/u/julien_goo)\
**Replies:** 3\
**Last updated:** [July 17, 2020, 6:20am UTC](https://discourse.julialang.org/t/archgdal-memory-issue-with-vector-data/42827 "2020-07-17T06:20:29Z")

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Hello all, I’m starting to use geo data in Julia with ArcGDAL, after using the R sf package for a while. My use case is simple : I have WGS 84 positions and I want to guess the timezone they belong to. I have the world…

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## [Read array of strings into Dictionary of DataFrames](https://discourse.julialang.org/t/read-array-of-strings-into-dictionary-of-dataframes/43202)

<div class="topic-metadata">

**Author:** [@evad](https://discourse.julialang.org/u/evad)\
**Replies:** 1\
**Last updated:** [July 17, 2020, 6:19am UTC](https://discourse.julialang.org/t/read-array-of-strings-into-dictionary-of-dataframes/43202 "2020-07-17T06:19:19Z")

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Hi, I have an array of strings where each string is a stream of multiple tables. And the final step of my function is to create and return a dictionary: function readTables(str) nStrs = split(str,"\\r\\n%T\\t") fHea…

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