# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1597

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

**Page:** 1598

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## [What is special about Array, String, and Symbol?](https://discourse.julialang.org/t/what-is-special-about-array-string-and-symbol/48557)

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**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 19\
**Last updated:** [October 20, 2020, 1:42pm UTC](https://discourse.julialang.org/t/what-is-special-about-array-string-and-symbol/48557 "2020-10-20T13:42:52Z")

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In the talk “What’s Bad in Julia” from JuliaCon 2019, one thing briefly mentioned from 4:40 to 5:13 is how users cannot define new types that use the memory layout tricks of Array, String, and Symbol, which makes these t…

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## [Easiest way to load a DataFrame from a compressed, newline delimited json file on the cloud?](https://discourse.julialang.org/t/easiest-way-to-load-a-dataframe-from-a-compressed-newline-delimited-json-file-on-the-cloud/48678)

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**Author:** [@s-kap](https://discourse.julialang.org/u/s-kap)\
**Replies:** 2\
**Last updated:** [October 20, 2020, 1:08pm UTC](https://discourse.julialang.org/t/easiest-way-to-load-a-dataframe-from-a-compressed-newline-delimited-json-file-on-the-cloud/48678 "2020-10-20T13:08:38Z")

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I’m trying to convert a python notebook into Julia. In python we have pd.read\_json("gs://bucket/file.json.gz", lines=True, compression="gzip") I don’t think there’s a way to do this. The approach I’ve taken is to fir…

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## [Weave won't convert a tex to pdf, because it says the directory is not empty](https://discourse.julialang.org/t/weave-wont-convert-a-tex-to-pdf-because-it-says-the-directory-is-not-empty/48670)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 2\
**Last updated:** [October 20, 2020, 12:56pm UTC](https://discourse.julialang.org/t/weave-wont-convert-a-tex-to-pdf-because-it-says-the-directory-is-not-empty/48670 "2020-10-20T12:56:18Z")

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I’m getting an error that the directory is not empty. How do I fix this? @pdeffebach, you’re the weave guy, how do I resolve this?

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## [@df macro under StatsPlots](https://discourse.julialang.org/t/df-macro-under-statsplots/48675)

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**Author:** [@Mun\_Barimukh](https://discourse.julialang.org/u/Mun_Barimukh)\
**Replies:** 5\
**Last updated:** [October 20, 2020, 9:34am UTC](https://discourse.julialang.org/t/df-macro-under-statsplots/48675 "2020-10-20T09:34:34Z")

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I have used “using StatsPlots;@df df plot(:a, \[:b :c\], colour = \[:red :blue\])”. Once I have got the result. But later on it has been showing @df not defined. How to fix it? Please help me out here.

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## [How to use ConfParser.jl to read INI file with custom comment prefix](https://discourse.julialang.org/t/how-to-use-confparser-jl-to-read-ini-file-with-custom-comment-prefix/48652)

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**Author:** [@vsskanth](https://discourse.julialang.org/u/vsskanth)\
**Replies:** 1\
**Last updated:** [October 20, 2020, 8:24am UTC](https://discourse.julialang.org/t/how-to-use-confparser-jl-to-read-ini-file-with-custom-comment-prefix/48652 "2020-10-20T08:24:55Z")

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I’m new to Julia and I am trying to convert a piece of python code that reads a TIR file (which is like an INI file with different prefixes for comments). tir\_parser = ConfigParser( strict = False, c…

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## [Can I Change Font Sizes in Julia Markdown?](https://discourse.julialang.org/t/can-i-change-font-sizes-in-julia-markdown/48599)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 4\
**Last updated:** [October 20, 2020, 8:06am UTC](https://discourse.julialang.org/t/can-i-change-font-sizes-in-julia-markdown/48599 "2020-10-20T08:06:27Z")

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Is there a way in julia Markdown, to have the font size of an output changed? I have a representation of a cantor set. const width = 81 const height = 5 function cantor!(lines, start, len, idx) seg = div(len, 3) …

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## [Rotate a subplot in MakieLayout?](https://discourse.julialang.org/t/rotate-a-subplot-in-makielayout/48573)

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**Author:** [@wherrera](https://discourse.julialang.org/u/wherrera)\
**Replies:** 3\
**Last updated:** [October 20, 2020, 6:46am UTC](https://discourse.julialang.org/t/rotate-a-subplot-in-makielayout/48573 "2020-10-20T06:46:01Z")

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I am trying to make the individual cubes in the grid of graphs rotate below, but get: "ERROR: MethodError: no method matching transformation(::LAxis) I am not sure how to refer to a specific axis or subscene’s mesh to r…

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## [Graph Piecewise Function in Julia](https://discourse.julialang.org/t/graph-piecewise-function-in-julia/48662)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 6\
**Last updated:** [October 20, 2020, 7:41am UTC](https://discourse.julialang.org/t/graph-piecewise-function-in-julia/48662 "2020-10-20T07:41:35Z")

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How do graph a piecewise function?

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## [Need help plotting using Blink and Interact](https://discourse.julialang.org/t/need-help-plotting-using-blink-and-interact/48644)

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**Author:** [@groovyda](https://discourse.julialang.org/u/groovyda)\
**Replies:** 1\
**Last updated:** [October 20, 2020, 6:56am UTC](https://discourse.julialang.org/t/need-help-plotting-using-blink-and-interact/48644 "2020-10-20T06:56:26Z")

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Hi there I have a simple interactive plot (in Pluto) that is slow - and should benefit from using Blink instead. I have spent the last day trying to make it work, but I just can’t figure out how to. Could someone pleas…

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## [Adding a simple constraint in Optim.jl optimizer](https://discourse.julialang.org/t/adding-a-simple-constraint-in-optim-jl-optimizer/48497)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 1\
**Last updated:** [October 20, 2020, 6:11am UTC](https://discourse.julialang.org/t/adding-a-simple-constraint-in-optim-jl-optimizer/48497 "2020-10-20T06:11:40Z")

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I have a simple optimizing code that I would like to add a constraint to. I think it may fall under nonlinear optimization (so potentially NLopt.jl) but I have no idea. The function is defined as the sum of squared diff…

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## [Sandboxing embedded Julia](https://discourse.julialang.org/t/sandboxing-embedded-julia/48643)

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**Author:** [@gmoromisato](https://discourse.julialang.org/u/gmoromisato)\
**Replies:** 6\
**Last updated:** [October 20, 2020, 5:56am UTC](https://discourse.julialang.org/t/sandboxing-embedded-julia/48643 "2020-10-20T05:56:54Z")

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I’m writing a server that allows people to write and run Julia programs in the cloud (similar to Repl.it). What are some tips for sandboxing Julia so that programmers can’t trash the server? How do I redirect stdin/st…

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## [Identify important subspaces of a function without squaring the conditioning number](https://discourse.julialang.org/t/identify-important-subspaces-of-a-function-without-squaring-the-conditioning-number/48664)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 2\
**Last updated:** [October 20, 2020, 4:06am UTC](https://discourse.julialang.org/t/identify-important-subspaces-of-a-function-without-squaring-the-conditioning-number/48664 "2020-10-20T04:06:19Z")

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Hello, I would like to find the important directions in the input and output spaces for a \\mu-measurable function f: \\mathbb{R}^n \\xrightarrow{} \\mathbb{R}^d. One way to identify these directions is to look at the eige…

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## [Using test.jl to prove trig identies](https://discourse.julialang.org/t/using-test-jl-to-prove-trig-identies/48654)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 9\
**Last updated:** [October 19, 2020, 11:46pm UTC](https://discourse.julialang.org/t/using-test-jl-to-prove-trig-identies/48654 "2020-10-19T23:46:14Z")

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I’m trying to do a proof using trig identities, I get a fail, and I,m not sure if I’m using @test wrong, or if I made a mistake in my math s.t. cos(x)-cos(y)=-2\*(sin((x+y)/2)\*sin((x-y)/2)) using Plots using test FX=f…

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## [Reading multiple text files from a directory](https://discourse.julialang.org/t/reading-multiple-text-files-from-a-directory/48661)

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**Author:** [@johnberg1](https://discourse.julialang.org/u/johnberg1)\
**Replies:** 1\
**Last updated:** [October 19, 2020, 10:57pm UTC](https://discourse.julialang.org/t/reading-multiple-text-files-from-a-directory/48661 "2020-10-19T22:57:13Z")

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Hello all, I am very new to Julia and I have a question regarding reading some files. I need to read 12500 .txt files from the same directory and save them all into 1 array but I’m having performance issues. Is there a f…

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## [CUDA Error in constant CuArray with conditional usage](https://discourse.julialang.org/t/cuda-error-in-constant-cuarray-with-conditional-usage/48581)

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**Author:** [@ozmaden](https://discourse.julialang.org/u/ozmaden)\
**Replies:** 3\
**Last updated:** [October 19, 2020, 10:37pm UTC](https://discourse.julialang.org/t/cuda-error-in-constant-cuarray-with-conditional-usage/48581 "2020-10-19T22:37:12Z")

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Hi everyone, I am confronted with an error concerning a constant CuArray. Any help would be greatly appreciated. Quick context: I’m one of the developers of the GNSSSignals package, adapting it to do signal processing …

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## [Juno.@enter/run myfunction() equivalent in vs code?](https://discourse.julialang.org/t/juno-enter-run-myfunction-equivalent-in-vs-code/48659)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 1\
**Last updated:** [October 19, 2020, 10:25pm UTC](https://discourse.julialang.org/t/juno-enter-run-myfunction-equivalent-in-vs-code/48659 "2020-10-19T22:25:32Z")

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Is this possible? All I’ve managed to do is set a break point at the line containing the call to myfunction() and re-run everything, then step in… Obviously the issue is that this could take a long time vs just hitting…

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## [Dynamic Code Loading to Use Packages on Demand](https://discourse.julialang.org/t/dynamic-code-loading-to-use-packages-on-demand/48655)

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**Author:** [@TheCedarPrince](https://discourse.julialang.org/u/TheCedarPrince)\
**Replies:** 3\
**Last updated:** [October 19, 2020, 10:02pm UTC](https://discourse.julialang.org/t/dynamic-code-loading-to-use-packages-on-demand/48655 "2020-10-19T22:02:23Z")

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I ran into an interesting problem today that I am trying to figure out (along with @Wikunia and @arsh). Basically, it stems from the idea of trying to load specific packages by user demand. The specific issue we are work…

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## [Is UnionAll abstract? Is it bad for performance?](https://discourse.julialang.org/t/is-unionall-abstract-is-it-bad-for-performance/48653)

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**Author:** [@JamesK](https://discourse.julialang.org/u/JamesK)\
**Replies:** 1\
**Last updated:** [October 19, 2020, 9:37pm UTC](https://discourse.julialang.org/t/is-unionall-abstract-is-it-bad-for-performance/48653 "2020-10-19T21:37:37Z")

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Sorry in advance if this is covered somewhere; I’m still a beginner. I’m concerned about the two performance tips as they relate to UnionAll: 1) Avoid fields with abstract type and 2) Avoid containers with abstract type…

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## [Is there a Julia Pkg for user data dir (appdirs)?](https://discourse.julialang.org/t/is-there-a-julia-pkg-for-user-data-dir-appdirs/48632)

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**Author:** [@zkamvar](https://discourse.julialang.org/u/zkamvar)\
**Replies:** 5\
**Last updated:** [October 19, 2020, 9:28pm UTC](https://discourse.julialang.org/t/is-there-a-julia-pkg-for-user-data-dir-appdirs/48632 "2020-10-19T21:28:35Z")

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I’m curious if there are any Julia Pkgs that port python’s appdirs.

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## [Help in installing Turing.jl](https://discourse.julialang.org/t/help-in-installing-turing-jl/48648)

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**Author:** [@bugs\_san](https://discourse.julialang.org/u/bugs_san)\
**Replies:** 1\
**Last updated:** [October 19, 2020, 8:42pm UTC](https://discourse.julialang.org/t/help-in-installing-turing-jl/48648 "2020-10-19T20:42:01Z")

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I have been trying to install Turing.jl I installed julia using this blog. I have been using other packages without any issues I am getting the below error when I use using Turing \`┌ Info: Precompiling Turing \[fce5fe8…

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## [QP returns NUMERICAL\_ERROR status](https://discourse.julialang.org/t/qp-returns-numerical-error-status/48630)

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**Author:** [@arkanver](https://discourse.julialang.org/u/arkanver)\
**Replies:** 3\
**Last updated:** [October 19, 2020, 5:38pm UTC](https://discourse.julialang.org/t/qp-returns-numerical-error-status/48630 "2020-10-19T17:38:37Z")

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Hello all, I have been trying to solve a quadratic problem with linear and box constraints. My objective function is convex. In most cases the problem gets solved fine (OPTIMAL status), but sometimes on larger examples …

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## [Why is 2^63 negative?](https://discourse.julialang.org/t/why-is-2-63-negative/48513)

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**Author:** [@timvink](https://discourse.julialang.org/u/timvink)\
**Replies:** 16\
**Last updated:** [October 19, 2020, 7:10pm UTC](https://discourse.julialang.org/t/why-is-2-63-negative/48513 "2020-10-19T19:10:57Z")

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Hi :wave: Making my first steps into julia, coming from R and python. Following the getting started guide, I noticed the following: 2^62 # 4611686018427387904 2^63 # \<--- This is negative? # -9223372036854775808 2^63 \> …

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## [Odd result with negative exponents of 10 in Julia 1.5.2](https://discourse.julialang.org/t/odd-result-with-negative-exponents-of-10-in-julia-1-5-2/48640)

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**Author:** [@David\_K](https://discourse.julialang.org/u/David_K)\
**Replies:** 4\
**Last updated:** [October 19, 2020, 6:05pm UTC](https://discourse.julialang.org/t/odd-result-with-negative-exponents-of-10-in-julia-1-5-2/48640 "2020-10-19T18:05:16Z")

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Hi, I’m relatively new to Julia and just installed version 1.5.2. Can someone explain to me how exponentiation works in this language? This might be incredibly basic, but negative exponents of 10 that are less than -1 th…

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## [Save Matrix of RGB Values to Image File with Huge Pixels](https://discourse.julialang.org/t/save-matrix-of-rgb-values-to-image-file-with-huge-pixels/47771)

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**Author:** [@pascal-mueller](https://discourse.julialang.org/u/pascal-mueller)\
**Replies:** 10\
**Last updated:** [October 19, 2020, 5:23pm UTC](https://discourse.julialang.org/t/save-matrix-of-rgb-values-to-image-file-with-huge-pixels/47771 "2020-10-19T17:23:09Z")

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Hi, so yesterday I tried to visualize a graph in the form of a matrix. A lot of people helped me in the forum and the chat. I ended up with turning the numerical values in my matrix to RGB values. So now I have e.g.: u…

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## [NASA Funding for Open Source Software](https://discourse.julialang.org/t/nasa-funding-for-open-source-software/48634)

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**Author:** [@ezaron](https://discourse.julialang.org/u/ezaron)\
**Replies:** 0\
**Last updated:** [October 19, 2020, 2:50pm UTC](https://discourse.julialang.org/t/nasa-funding-for-open-source-software/48634 "2020-10-19T14:50:16Z")

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Sorry for the bad cut-and-paste from the NASA SMD listserv. Enough keyword are in the text, below, to allow you to find the original documents online. I wanted to make sure this community was aware of opportunities for …

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## [Why does code in a package use "using" and "import"?](https://discourse.julialang.org/t/why-does-code-in-a-package-use-using-and-import/48500)

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**Author:** [@lyonsquark](https://discourse.julialang.org/u/lyonsquark)\
**Replies:** 13\
**Last updated:** [October 19, 2020, 1:50pm UTC](https://discourse.julialang.org/t/why-does-code-in-a-package-use-using-and-import/48500 "2020-10-19T13:50:07Z")

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Hi, In looking at how Julia packages are implemented, I see a common idiom that I don’t quite understand. For example, if you look at YaoBase/src/YaoBase.jl at https://github.com/QuantumBFS/YaoBase.jl/blob/master/src/Yao…

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## [Fitting of distribution histogram - axis-limit issues and problems with defining goodness of fit?](https://discourse.julialang.org/t/fitting-of-distribution-histogram-axis-limit-issues-and-problems-with-defining-goodness-of-fit/48617)

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**Author:** [@MJMAG](https://discourse.julialang.org/u/MJMAG)\
**Replies:** 1\
**Last updated:** [October 19, 2020, 1:48pm UTC](https://discourse.julialang.org/t/fitting-of-distribution-histogram-axis-limit-issues-and-problems-with-defining-goodness-of-fit/48617 "2020-10-19T13:48:57Z")

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Hey Community, I am facing the following “problem”: I am supposed to find a growth rate distribution in a certain data set. For this I am looking at new objects being created at a timestep. These counts I want to illus…

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## [TAR.create with a collection of file paths](https://discourse.julialang.org/t/tar-create-with-a-collection-of-file-paths/48626)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 0\
**Last updated:** [October 19, 2020, 1:19pm UTC](https://discourse.julialang.org/t/tar-create-with-a-collection-of-file-paths/48626 "2020-10-19T13:19:13Z")

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Is there a simple way to build a tarball from a list of files? From the docs it seems like I’ll need to give it the parent directory of all of the files, so potentially /, and then a predicate function, so something lik…

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## [How to read φ and π in @code\_typed output?](https://discourse.julialang.org/t/how-to-read-and-in-code-typed-output/48623)

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**Author:** [@igloo](https://discourse.julialang.org/u/igloo)\
**Replies:** 2\
**Last updated:** [October 19, 2020, 1:09pm UTC](https://discourse.julialang.org/t/how-to-read-and-in-code-typed-output/48623 "2020-10-19T13:09:23Z")

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Take for example the following snippet. 5 ── goto #6 6 ── %26 = Base.sub\_float(%23, 1.0)::Float64 └─── goto #7 7 ── goto #8 8 ── goto #9 9 ── %30 = Base.lt\_float(0.5, %26)::Bool └─── goto #…

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## [Crash on access of EnsembleSolution](https://discourse.julialang.org/t/crash-on-access-of-ensemblesolution/48620)

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**Author:** [@peatlux](https://discourse.julialang.org/u/peatlux)\
**Replies:** 8\
**Last updated:** [October 19, 2020, 1:09pm UTC](https://discourse.julialang.org/t/crash-on-access-of-ensemblesolution/48620 "2020-10-19T13:09:09Z")

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Hello, I’ve experienced a crash of julia when I wanted to access my EnsembleSolution. The message told me to report the bug. Since I don’t know where to report it, I do it here. Below is my code to produce the EnsembleS…

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