# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=695

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

**Page:** 696

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## [What IDE do you use?](https://discourse.julialang.org/t/what-ide-do-you-use/47006)

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**Author:** [@MathMan](https://discourse.julialang.org/u/MathMan)\
**Replies:** 55\
**Last updated:** [October 1, 2020, 12:35pm UTC](https://discourse.julialang.org/t/what-ide-do-you-use/47006 "2020-10-01T12:35:30Z")

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Just because I am curious: What IDEs are you using to code with Julia? Since debugging (setting breakpoints, observing variables etc.) is mandatory for code development, I am woundering how you do this. I started with v…

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## [Julia equivalent to Python's int.to\_bytes](https://discourse.julialang.org/t/julia-equivalent-to-pythons-int-to-bytes/44038)

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**Author:** [@louie4825](https://discourse.julialang.org/u/louie4825)\
**Replies:** 14\
**Last updated:** [October 1, 2020, 11:56am UTC](https://discourse.julialang.org/t/julia-equivalent-to-pythons-int-to-bytes/44038 "2020-10-01T11:56:08Z")

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Hi everyone :\> I’ve been using Julia the past few days, and so far I’ve been enjoying it. I’ve been trying to replicate Python functionality as a little exercise in Julia, but now I’m getting stuck on Python’s int.to\_by…

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## [Unexpected behaviour of include](https://discourse.julialang.org/t/unexpected-behaviour-of-include/47589)

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**Author:** [@jhbdiehl](https://discourse.julialang.org/u/jhbdiehl)\
**Replies:** 2\
**Last updated:** [October 1, 2020, 11:39am UTC](https://discourse.julialang.org/t/unexpected-behaviour-of-include/47589 "2020-10-01T11:39:13Z")

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pwd() and include() do not seem to agree on which working directory I am in. Using Julia 1.5 on VS code. I have a directory structure resembling ./FolderA/FolderB with my files being in FolderB. pwd() in the Julia REPL…

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## [Resources for writing a parser/lexer](https://discourse.julialang.org/t/resources-for-writing-a-parser-lexer/47355)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 6\
**Last updated:** [October 1, 2020, 7:55am UTC](https://discourse.julialang.org/t/resources-for-writing-a-parser-lexer/47355 "2020-10-01T07:55:27Z")

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Hi I have to write a parser for a simple Syntax and I was wondering if there are already resources to help me do that. Any hints are welcome. :wink: Example input: group=name { Section1 { key1 = value1 key2 = value2, …

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## [Collecting homogenized vectors: modify iterator vs modify collector](https://discourse.julialang.org/t/collecting-homogenized-vectors-modify-iterator-vs-modify-collector/42957)

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**Author:** [@BMO](https://discourse.julialang.org/u/BMO)\
**Replies:** 3\
**Last updated:** [September 30, 2020, 5:24pm UTC](https://discourse.julialang.org/t/collecting-homogenized-vectors-modify-iterator-vs-modify-collector/42957 "2020-09-30T17:24:38Z")

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Nemo is a computer algebra package for the Julia programming language. For a multivariated polynomial p there is an iterator exponent\_vectors(p) whose values are vectors corresponding to the exponents of the terms of p (…

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## [Find minimum argument with custom comparator](https://discourse.julialang.org/t/find-minimum-argument-with-custom-comparator/47561)

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**Author:** [@timquelch](https://discourse.julialang.org/u/timquelch)\
**Replies:** 6\
**Last updated:** [October 1, 2020, 5:21am UTC](https://discourse.julialang.org/t/find-minimum-argument-with-custom-comparator/47561 "2020-10-01T05:21:56Z")

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I feel like something is missing from the available minimum functions. I’ve come across the issue multiple times where i want to get the value of a collection that gives the minimum value of a specified function. i.e. I …

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## [Why might I be seeing a large overhead for multiprocessing?](https://discourse.julialang.org/t/why-might-i-be-seeing-a-large-overhead-for-multiprocessing/47547)

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**Author:** [@JamesK](https://discourse.julialang.org/u/JamesK)\
**Replies:** 8\
**Last updated:** [October 1, 2020, 5:07am UTC](https://discourse.julialang.org/t/why-might-i-be-seeing-a-large-overhead-for-multiprocessing/47547 "2020-10-01T05:07:07Z")

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I have an 8 core machine. When I run a certain piece of code with Python’s multiprocessing.Pool library, with 1 core vs. 4 cores, I see an almost 4x speedup for the 4 core case, with very little overhead penalty, assumi…

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## [Dataframes with groupby in parallel](https://discourse.julialang.org/t/dataframes-with-groupby-in-parallel/47186)

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**Author:** [@bicepjai](https://discourse.julialang.org/u/bicepjai)\
**Replies:** 1\
**Last updated:** [October 1, 2020, 4:39am UTC](https://discourse.julialang.org/t/dataframes-with-groupby-in-parallel/47186 "2020-10-01T04:39:06Z")

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I have a dataframe of size (2450225, 117) Just using pandas and multiprocessing module, gives me the results in 34 seconds. I have panda code below. I am trying to achieve the same with julia and hoping this would be a …

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## [Dataframes: How to conditionally remove rows based on data values?](https://discourse.julialang.org/t/dataframes-how-to-conditionally-remove-rows-based-on-data-values/47538)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 4\
**Last updated:** [October 1, 2020, 1:52am UTC](https://discourse.julialang.org/t/dataframes-how-to-conditionally-remove-rows-based-on-data-values/47538 "2020-10-01T01:52:06Z")

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Dear folks, I fail to remove rows in a dataframe based on conditions. Here is an MWE: The dataframe is │ Row │ A │ B │ │ │ String │ String │ ├─────┼────────┼────────┤ │ 1 │ X │ C │ │ 2 │ X …

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## [Plotting curvilinear coordinate function on Cartesian plane](https://discourse.julialang.org/t/plotting-curvilinear-coordinate-function-on-cartesian-plane/47294)

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**Author:** [@kapple](https://discourse.julialang.org/u/kapple)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 11:54pm UTC](https://discourse.julialang.org/t/plotting-curvilinear-coordinate-function-on-cartesian-plane/47294 "2020-09-30T23:54:08Z")

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Suppose I have the following curvilinear coordinate (s, n) transform to Cartesian coordinates (x, y, z) x = f(s, n) \\\\ y = g(s, n) \\\\ z = h(s, n) where f(s, n), g(s, n), and h(s, n) are inaccessible functions (i.e. th…

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## [How to debug compiler hang?](https://discourse.julialang.org/t/how-to-debug-compiler-hang/47559)

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**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 0\
**Last updated:** [September 30, 2020, 11:23pm UTC](https://discourse.julialang.org/t/how-to-debug-compiler-hang/47559 "2020-09-30T23:23:30Z")

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I’ve got a piece of long-running code which runs for about 5min, then, on what seems like a totally benign command, hangs for like 10minutes, every time. It does eventually complete and continue running after that. I thi…

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## [Troubles with gcc 9](https://discourse.julialang.org/t/troubles-with-gcc-9/47550)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 7:46pm UTC](https://discourse.julialang.org/t/troubles-with-gcc-9/47550 "2020-09-30T19:46:09Z")

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A GMT user posted an issue that I was able to reproduce in WSL2 + gcc9. The error is ERROR: LoadError: LoadError: could not load library "/home/j/programs/lib/libgmt.so" /home/j/programs/julia/bin/../lib/julia/libstdc++…

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## [Sundials solver options question, is dt ignored(initial step), and is maxorder a viable option? What is the default, 4?](https://discourse.julialang.org/t/sundials-solver-options-question-is-dt-ignored-initial-step-and-is-maxorder-a-viable-option-what-is-the-default-4/47549)

<div class="topic-metadata">

**Author:** [@cbasile21](https://discourse.julialang.org/u/cbasile21)\
**Replies:** 2\
**Last updated:** [September 30, 2020, 7:22pm UTC](https://discourse.julialang.org/t/sundials-solver-options-question-is-dt-ignored-initial-step-and-is-maxorder-a-viable-option-what-is-the-default-4/47549 "2020-09-30T19:22:44Z")

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The solver compatibility chart, says that dt is ignored for sundials, is this correct? I did not see any errors when using it. Moreover, is maxorder a viable option? Is the default for CVODE\_BDF 4 or 5? Can it be changed…

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## [Help me figure out where to file this bug?](https://discourse.julialang.org/t/help-me-figure-out-where-to-file-this-bug/47512)

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**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 3\
**Last updated:** [September 30, 2020, 5:07pm UTC](https://discourse.julialang.org/t/help-me-figure-out-where-to-file-this-bug/47512 "2020-09-30T17:07:41Z")

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I’m summarizing some data (that I can’t show you, it’s part of a lawsuit) and I’m running the following command through Query.jl… if I leave out the part uniquen = length(unique(\_.customer\_id)) everything works, but if I…

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## [How to install PyPlot.jl on Windows 10 behind a firewall](https://discourse.julialang.org/t/how-to-install-pyplot-jl-on-windows-10-behind-a-firewall/30208)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 6\
**Last updated:** [September 30, 2020, 12:32pm UTC](https://discourse.julialang.org/t/how-to-install-pyplot-jl-on-windows-10-behind-a-firewall/30208 "2020-09-30T12:32:54Z")

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I am behind a firewall and have to use a proxy server. This works for normal Julia packages, but not for Python/ Conda. The following command fails: (v1.2) pkg\> build PyCall Building Conda ─→ \`C:\\Users\\NLUWFEC\\.julia\\…

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## [In-place reverse!](https://discourse.julialang.org/t/in-place-reverse/47524)

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**Author:** [@greg\_plowman](https://discourse.julialang.org/u/greg_plowman)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 11:24am UTC](https://discourse.julialang.org/t/in-place-reverse/47524 "2020-09-30T11:24:33Z")

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In-place reverse! is defined for vectors. Does it make sense to have reverse! for general arrays with other dimensions? In particular, I thought it might useful for matrices?

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## [Simple syntax for modifying specific entries of one Array based on indices from another Array?](https://discourse.julialang.org/t/simple-syntax-for-modifying-specific-entries-of-one-array-based-on-indices-from-another-array/47494)

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**Author:** [@airpmb](https://discourse.julialang.org/u/airpmb)\
**Replies:** 5\
**Last updated:** [September 30, 2020, 11:07am UTC](https://discourse.julialang.org/t/simple-syntax-for-modifying-specific-entries-of-one-array-based-on-indices-from-another-array/47494 "2020-09-30T11:07:44Z")

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How would I do this? It seems like there should be some simple syntax for this but if so, I can’t find it. For example, suppose I have a 10x10 matrix A, and a 5x2 matrix idx, and the rows of idx represent row, column in…

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## [How to link to the repo's NEWS.md in the documentation?](https://discourse.julialang.org/t/how-to-link-to-the-repos-news-md-in-the-documentation/47477)

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**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 3\
**Last updated:** [September 30, 2020, 9:23am UTC](https://discourse.julialang.org/t/how-to-link-to-the-repos-news-md-in-the-documentation/47477 "2020-09-30T09:23:19Z")

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I notice that the link to “news” in the documentation for Interpolations.jl is broken. Currently the link points to ../../NEWS.md. Given the directory structure docs/src/index.md, this appears to be the correct relative …

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

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**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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## [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)

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

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**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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