# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1616

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

**Page:** 1617

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## [Are generated functions threadsafe?](https://discourse.julialang.org/t/are-generated-functions-threadsafe/47527)

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**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 8:56am UTC](https://discourse.julialang.org/t/are-generated-functions-threadsafe/47527 "2020-09-30T08:56:09Z")

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Is it true that generated functions (not their bodies) always run on the main thread? I had assumed so, but now that I think of it I’m not sure I’ve ever seen that actually confirmed, so just wanted to verify. Basically,…

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## [Csv dateformat](https://discourse.julialang.org/t/csv-dateformat/47480)

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**Author:** [@dmetivie](https://discourse.julialang.org/u/dmetivie)\
**Replies:** 2\
**Last updated:** [September 30, 2020, 8:53am UTC](https://discourse.julialang.org/t/csv-dateformat/47480 "2020-09-30T08:53:52Z")

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Hello, I want to import data with a structure like that code,date 0,20190101 1,20190102 If I do t = CSV.read("file.txt"; dateformat="yyyymmdd") 2×2 DataFrame │ Row │ code │ date │ │ │ Int64 │ Int64 │ ├──…

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## [R's dplyr and data.table 2x faster than Julia's DataFrames.jl + libraries](https://discourse.julialang.org/t/rs-dplyr-and-data-table-2x-faster-than-julias-dataframes-jl-libraries/47465)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 9\
**Last updated:** [September 30, 2020, 3:17am UTC](https://discourse.julialang.org/t/rs-dplyr-and-data-table-2x-faster-than-julias-dataframes-jl-libraries/47465 "2020-09-30T03:17:40Z")

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I got this data from Home Credit Default Risk | Kaggle and I just downloaded the data and loaded them and run the below. TLDR: R seems 2x as fast! using DataFrames, Statistics, DataFramesMeta using DataConvenience usin…

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## [Does Pkg provide information about available versions of registered packages?](https://discourse.julialang.org/t/does-pkg-provide-information-about-available-versions-of-registered-packages/47516)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 0\
**Last updated:** [September 30, 2020, 1:40am UTC](https://discourse.julialang.org/t/does-pkg-provide-information-about-available-versions-of-registered-packages/47516 "2020-09-30T01:40:26Z")

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If not, wouldn’t that be a good enhancement?

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## [Tests fail with 1.6 dev](https://discourse.julialang.org/t/tests-fail-with-1-6-dev/47506)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 3\
**Last updated:** [September 29, 2020, 10:25pm UTC](https://discourse.julialang.org/t/tests-fail-with-1-6-dev/47506 "2020-09-29T22:25:06Z")

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Am I the only one seeing this? The tests actually pass but fail at the end during the cleaning stage due to permission problems. Testing GMT Status \`C:\\TMP\\jl\_Kq6FYF\\Project.toml\` \[5752ebe1\] GMT v0.25.0 \`C:\\Users\\…

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## [How to pass a relative UnitRange to a function?](https://discourse.julialang.org/t/how-to-pass-a-relative-unitrange-to-a-function/47431)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 9\
**Last updated:** [September 29, 2020, 10:10pm UTC](https://discourse.julialang.org/t/how-to-pass-a-relative-unitrange-to-a-function/47431 "2020-09-29T22:10:46Z")

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I have the following which tries to apply a relative unit range to a string whose length is unknown: function testnums(data::String,numrange::String) data\[numrange\] end foo = "asdfasdfasdf" bar = "end-3:end" testnu…

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## [Cant create dataframe](https://discourse.julialang.org/t/cant-create-dataframe/47502)

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**Author:** [@andresmorago](https://discourse.julialang.org/u/andresmorago)\
**Replies:** 16\
**Last updated:** [September 29, 2020, 10:00pm UTC](https://discourse.julialang.org/t/cant-create-dataframe/47502 "2020-09-29T22:00:16Z")

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Hello guys. Newbie here I have this array getvalue.(W) 1-dimensional DenseAxisArray{Float64,1,…} with index sets: Dimension 1, 0:6 And data, a 7-element Array{Float64,1}: 80.0 65.0 65.0 65.0 65.0 65.0 65.0 …

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## [Zygote mutating arrays is not supported](https://discourse.julialang.org/t/zygote-mutating-arrays-is-not-supported/47467)

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**Author:** [@rezabayani](https://discourse.julialang.org/u/rezabayani)\
**Replies:** 2\
**Last updated:** [September 29, 2020, 8:31pm UTC](https://discourse.julialang.org/t/zygote-mutating-arrays-is-not-supported/47467 "2020-09-29T20:31:37Z")

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I have a problem with differentiation in Zygote. Let me start with an example of what I need to achieve: If we have a vector like a = \[0,2,4,1\], and b = 2, I would like to create a vector which is a binary, with ones as…

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## [Load large Datamatrix with column and rownames](https://discourse.julialang.org/t/load-large-datamatrix-with-column-and-rownames/47498)

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**Author:** [@MalteMederacke](https://discourse.julialang.org/u/MalteMederacke)\
**Replies:** 3\
**Last updated:** [September 29, 2020, 7:45pm UTC](https://discourse.julialang.org/t/load-large-datamatrix-with-column-and-rownames/47498 "2020-09-29T19:45:48Z")

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I need to read multiple large DataMatrices from a tsv into julia. They have column AND rownames. Do I have to realy read it in first and then slice the first column? What would be the best approach

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## [Implementing Crystal Graph CNN in Julia](https://discourse.julialang.org/t/implementing-crystal-graph-cnn-in-julia/33169)

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**Author:** [@rkurchin](https://discourse.julialang.org/u/rkurchin)\
**Replies:** 4\
**Last updated:** [September 29, 2020, 6:56pm UTC](https://discourse.julialang.org/t/implementing-crystal-graph-cnn-in-julia/33169 "2020-09-29T18:56:11Z")

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Hi everyone! I’d like to implement Crystal Graph Convolutional Neural Networks (CGCNNs) in Julia, in particular using the GeometricFlux package. CGCNN’s are a method in computational materials science for representing cr…

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## [Debugging with CUDA.jl](https://discourse.julialang.org/t/debugging-with-cuda-jl/47493)

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**Author:** [@bmit](https://discourse.julialang.org/u/bmit)\
**Replies:** 1\
**Last updated:** [September 29, 2020, 5:50pm UTC](https://discourse.julialang.org/t/debugging-with-cuda-jl/47493 "2020-09-29T17:50:09Z")

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Does Debugger.jl work with CUDA.jl? I haven’t had any luck and wasn’t sure if I was missing something or it’s not supposed to work. Here’s the simplest case I came up with: using CUDA using Debugger function test\_cuda\_d…

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## [What scaling applies to the irfft (inverse fast fourier transform - FFTW.jl package)](https://discourse.julialang.org/t/what-scaling-applies-to-the-irfft-inverse-fast-fourier-transform-fftw-jl-package/47476)

<div class="topic-metadata">

**Author:** [@jleman](https://discourse.julialang.org/u/jleman)\
**Replies:** 4\
**Last updated:** [September 29, 2020, 5:28pm UTC](https://discourse.julialang.org/t/what-scaling-applies-to-the-irfft-inverse-fast-fourier-transform-fftw-jl-package/47476 "2020-09-29T17:28:37Z")

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I am trying to understand scaling of the irfft function of the FFTW.jl package. I have a function that defines a continuous frequency domain signal (in radians). The complex portion of the signal has odd symmetry and t…

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## [Mention of Julia for the re-implementation of PETSC](https://discourse.julialang.org/t/mention-of-julia-for-the-re-implementation-of-petsc/46199)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 25\
**Last updated:** [September 29, 2020, 3:30pm UTC](https://discourse.julialang.org/t/mention-of-julia-for-the-re-implementation-of-petsc/46199 "2020-09-29T15:30:40Z")

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If you have ideas and opinions, go see: Petsc-future: Languages (#645) · Issues · PETSc / petsc · GitLab

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## [DiffEqFlux Autodifferentiating inside loss function](https://discourse.julialang.org/t/diffeqflux-autodifferentiating-inside-loss-function/47203)

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**Author:** [@Axlrsn](https://discourse.julialang.org/u/Axlrsn)\
**Replies:** 6\
**Last updated:** [September 29, 2020, 3:03pm UTC](https://discourse.julialang.org/t/diffeqflux-autodifferentiating-inside-loss-function/47203 "2020-09-29T15:03:25Z")

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Hello, I am new to Julia and especially the way Zygote works. For a project in physics informed machine learning I have a neural network NN(x) approximating a function f(x). I want to take the gradient of the neural net…

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## [DiffeqOperators for non-uniform grid](https://discourse.julialang.org/t/diffeqoperators-for-non-uniform-grid/46802)

<div class="topic-metadata">

**Author:** [@JianghuiDu](https://discourse.julialang.org/u/JianghuiDu)\
**Replies:** 2\
**Last updated:** [September 29, 2020, 2:31pm UTC](https://discourse.julialang.org/t/diffeqoperators-for-non-uniform-grid/46802 "2020-09-29T14:31:43Z")

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I have a problem of using DiffeqOperators.jl on non-uniform grid. Here is an example of a simple diffusion equation D\\nabla^2C+1=0 between \[0,50\] with Robin boundary conditions on both side. It is solved using centered s…

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## [Ordered Dict in Base: Is LittleDict not thread safe, and possibly the reason I can't add it to Base?](https://discourse.julialang.org/t/ordered-dict-in-base-is-littledict-not-thread-safe-and-possibly-the-reason-i-cant-add-it-to-base/47372)

<div class="topic-metadata">

**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 11\
**Last updated:** [September 29, 2020, 2:19pm UTC](https://discourse.julialang.org/t/ordered-dict-in-base-is-littledict-not-thread-safe-and-possibly-the-reason-i-cant-add-it-to-base/47372 "2020-09-29T14:19:28Z")

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I’m working on a PR to Julia, already could add OrderedDict to Base, independent of Dict, or by replacing it. When replacing, it however makes some stuff slower. \[EDIT: short answer, dicts are not thread-safe, see soluti…

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## [Selecting multiple elements of an array by a list of indices](https://discourse.julialang.org/t/selecting-multiple-elements-of-an-array-by-a-list-of-indices/47483)

<div class="topic-metadata">

**Author:** [@amca01](https://discourse.julialang.org/u/amca01)\
**Replies:** 9\
**Last updated:** [September 29, 2020, 2:16pm UTC](https://discourse.julialang.org/t/selecting-multiple-elements-of-an-array-by-a-list-of-indices/47483 "2020-09-29T14:16:38Z")

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I have a list of indices, say inds = \[\[1,2\], \[2,3\],\[4,4\]\] that I want to use as indices into an array. For example, if A = reshape(1:16,4,4) then I would want to return the values \[5, 10, 16\]. I can, for example, use…

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## [Argument order in \`kron(A,B)\`](https://discourse.julialang.org/t/argument-order-in-kron-a-b/47481)

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**Author:** [@ettersi](https://discourse.julialang.org/u/ettersi)\
**Replies:** 5\
**Last updated:** [September 29, 2020, 1:59pm UTC](https://discourse.julialang.org/t/argument-order-in-kron-a-b/47481 "2020-09-29T13:59:07Z")

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Julia defines kron(A,B) such that kron(A,B)\*vec(C) = vec(B\*C\*A') while if I were to have my way I would define kron(A,B) such that kron(A,B)\*vec(C) = vec(A\*C\*B') # A and B are swapped Given Julia’s history of taking…

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## [Depend on a specific commit?](https://discourse.julialang.org/t/depend-on-a-specific-commit/47437)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 2\
**Last updated:** [September 29, 2020, 1:56pm UTC](https://discourse.julialang.org/t/depend-on-a-specific-commit/47437 "2020-09-29T13:56:17Z")

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I’m almost dead certain I have seen this asked before, but I just can’t find it. Assume I have a package A which needs a later version of a package B than what is released. The problem with just adding a version which …

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## [Best practices for Julia unit testing](https://discourse.julialang.org/t/best-practices-for-julia-unit-testing/30858)

<div class="topic-metadata">

**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 15\
**Last updated:** [September 29, 2020, 1:08pm UTC](https://discourse.julialang.org/t/best-practices-for-julia-unit-testing/30858 "2020-09-29T13:08:32Z")

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I have a few questions about unit testing workflows. Also, maybe we can use this thread to compile a list of best practices for unit testing which we can then contribute to the docs. 1 - where is runtests.jl supposed to…

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## [GPLK vs Gurobi speed on simple MIPs](https://discourse.julialang.org/t/gplk-vs-gurobi-speed-on-simple-mips/47383)

<div class="topic-metadata">

**Author:** [@adow031](https://discourse.julialang.org/u/adow031)\
**Replies:** 11\
**Last updated:** [September 29, 2020, 1:07pm UTC](https://discourse.julialang.org/t/gplk-vs-gurobi-speed-on-simple-mips/47383 "2020-09-29T13:07:21Z")

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I’m needing to solve a large number of simple MIPs in succession, and I’m finding that GPLK is 2.5 times faster than Gurobi (with presolve disabled; presolve slows Gurobi further). Is this normal? I know that for large/…

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## [PackageCompiler stores REPL histories?](https://discourse.julialang.org/t/packagecompiler-stores-repl-histories/47385)

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**Author:** [@dunrix](https://discourse.julialang.org/u/dunrix)\
**Replies:** 6\
**Last updated:** [September 29, 2020, 12:59pm UTC](https://discourse.julialang.org/t/packagecompiler-stores-repl-histories/47385 "2020-09-29T12:59:18Z")

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Hi, just played around with PackageCompiler and has been surprised what I’ve found in produced “executable” (rather shared library executable stub calls). In that huge ~90MiB file for a simplest "hello world\* program, …

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## [In-place map](https://discourse.julialang.org/t/in-place-map/47464)

<div class="topic-metadata">

**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 3\
**Last updated:** [September 29, 2020, 12:50pm UTC](https://discourse.julialang.org/t/in-place-map/47464 "2020-09-29T12:50:40Z")

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In-place map! seems to work: a = \[collect(1:3)..., -Inf, Inf, NaN\] map!(x -\> 0 \<= x \<= 10 ? x : 0.0, a, a) ..... julia\> a 6-element Array{Float64,1}: 1.0 2.0 3.0 0.0 0.0 0.0 Is it allowed? Assuming that it is, I…

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## [Why are there no curried versions of map & filter?](https://discourse.julialang.org/t/why-are-there-no-curried-versions-of-map-filter/47478)

<div class="topic-metadata">

**Author:** [@matklad](https://discourse.julialang.org/u/matklad)\
**Replies:** 5\
**Last updated:** [September 29, 2020, 10:47am UTC](https://discourse.julialang.org/t/why-are-there-no-curried-versions-of-map-filter/47478 "2020-09-29T10:47:25Z")

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I’ve written the following code today: branches = filter(strip.(readlines(\`git branch --merged\`))) do branch branch != "master" && !startswith(branch, '\*') end It’s OK, but I’d love to be able to write branches = …

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## [Squeeze/compress element type of array](https://discourse.julialang.org/t/squeeze-compress-element-type-of-array/47061)

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**Author:** [@DrChainsaw](https://discourse.julialang.org/u/DrChainsaw)\
**Replies:** 3\
**Last updated:** [September 23, 2020, 2:27pm UTC](https://discourse.julialang.org/t/squeeze-compress-element-type-of-array/47061 "2020-09-23T14:27:54Z")

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Does there exist any functionality which given an array returns a new array with the smallest eltype which can represent the data, i.e julia\> squeezeeltype(\[1,2,3\]) 3-element Array{UInt8,1}: 0x01 0x02 0x03 It seems …

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## [How to get libLLVM-9.0.1.so on Ubuntu 18.04 required by Cxx package?](https://discourse.julialang.org/t/how-to-get-libllvm-9-0-1-so-on-ubuntu-18-04-required-by-cxx-package/40950)

<div class="topic-metadata">

**Author:** [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)\
**Replies:** 15\
**Last updated:** [September 29, 2020, 9:42am UTC](https://discourse.julialang.org/t/how-to-get-libllvm-9-0-1-so-on-ubuntu-18-04-required-by-cxx-package/40950 "2020-09-29T09:42:09Z")

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With Julia 1.5.0-beta1 on Ubuntu 18.04.4 I’m getting: (@v1.5) pkg\> build Cxx Building Cxx → \`~/.julia/packages/Cxx/1RaOv/deps/build.log\` ┌ Error: Error building \`Cxx\`: │ ERROR: LoadError: could not load library "lib…

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## [Scraping a html table from a website](https://discourse.julialang.org/t/scraping-a-html-table-from-a-website/47378)

<div class="topic-metadata">

**Author:** [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)\
**Replies:** 2\
**Last updated:** [September 29, 2020, 9:37am UTC](https://discourse.julialang.org/t/scraping-a-html-table-from-a-website/47378 "2020-09-29T09:37:54Z")

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I am trying to obtain COVID-19 data from a website. The website has the data which I want but it is in a html table format I am looking for Julia tools to scrape the information from the html table. Something like this …

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## [How to start and structure a new application?](https://discourse.julialang.org/t/how-to-start-and-structure-a-new-application/46857)

<div class="topic-metadata">

**Author:** [@pascal-mueller](https://discourse.julialang.org/u/pascal-mueller)\
**Replies:** 12\
**Last updated:** [September 29, 2020, 9:19am UTC](https://discourse.julialang.org/t/how-to-start-and-structure-a-new-application/46857 "2020-09-29T09:19:34Z")

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Hi, I just read the docs about Pkg.jl and there in the glossary we can find the definition of the three words project, package and application. Project: is an umbrella term: packages and applications are kinds of proje…

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## [Counting words in StringArray](https://discourse.julialang.org/t/counting-words-in-stringarray/47398)

<div class="topic-metadata">

**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 12\
**Last updated:** [September 29, 2020, 8:10am UTC](https://discourse.julialang.org/t/counting-words-in-stringarray/47398 "2020-09-29T08:10:20Z")

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How to tount words in StringArray julia\> y=\["gastro" "gastro gastro "; "dom" "pies"\] 2×2 Array{String,2}: "gastro" "gastro gastro " "dom" "pies" julia\> occursin.(x,y) 2×2 BitArray{2}: 1 1 0 0 julia\> y.=="ga…

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## [IOError: stat: operation not permitted when import new package](https://discourse.julialang.org/t/ioerror-stat-operation-not-permitted-when-import-new-package/47425)

<div class="topic-metadata">

**Author:** [@byteb](https://discourse.julialang.org/u/byteb)\
**Replies:** 1\
**Last updated:** [September 29, 2020, 7:45am UTC](https://discourse.julialang.org/t/ioerror-stat-operation-not-permitted-when-import-new-package/47425 "2020-09-29T07:45:28Z")

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I have a Windows VM with two users: Administrator access Local user account (non-admin) access I have Julia installed in this Windows VM under the C:\\Julia folder. The Administrator use can install package and import …

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