# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=701

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**Page:** 702

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## [Starting a small local web server with HTTP.jl?](https://discourse.julialang.org/t/starting-a-small-local-web-server-with-http-jl/11668)

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**Author:** [@tlienart](https://discourse.julialang.org/u/tlienart)\
**Replies:** 18\
**Last updated:** [September 17, 2020, 9:38am UTC](https://discourse.julialang.org/t/starting-a-small-local-web-server-with-http-jl/11668 "2020-09-17T09:38:22Z")

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I’m looking for a way to host a local directory as a small, static, website. The local web server in Node.js offers exactly what I need (running ws in the terminal starts a local web server in the current directory whic…

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## [How to escape boolean operators in HTTP.escapeuri()?](https://discourse.julialang.org/t/how-to-escape-boolean-operators-in-http-escapeuri/46733)

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**Author:** [@mkarikom](https://discourse.julialang.org/u/mkarikom)\
**Replies:** 1\
**Last updated:** [September 17, 2020, 3:44am UTC](https://discourse.julialang.org/t/how-to-escape-boolean-operators-in-http-escapeuri/46733 "2020-09-17T03:44:40Z")

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I need to escape a string that has characters defined in the apache Lucene implementation Ex. 1 (the “+” asserts that the identifier intNum is included somewhere in the doc) +intNum%20NOT%20natNum # all non-positive in…

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## [Is it possible to define a \`\`+!\`\` function?](https://discourse.julialang.org/t/is-it-possible-to-define-a-function/46475)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 22\
**Last updated:** [September 16, 2020, 11:48pm UTC](https://discourse.julialang.org/t/is-it-possible-to-define-a-function/46475 "2020-09-16T23:48:52Z")

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Tried this but no luck. julia\> (+!)(x, y) = 0 ERROR: syntax: invalid function name "+(!)" around REPL\[35\]:1 or julia\> function +!(x, y) = 0 end ERROR: syntax: expected "end" in definition of function "+" The idea is…

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## [MixedModels.jl: how to get confidence intervals?](https://discourse.julialang.org/t/mixedmodels-jl-how-to-get-confidence-intervals/46730)

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**Author:** [@kai](https://discourse.julialang.org/u/kai)\
**Replies:** 0\
**Last updated:** [September 16, 2020, 9:06pm UTC](https://discourse.julialang.org/t/mixedmodels-jl-how-to-get-confidence-intervals/46730 "2020-09-16T21:06:17Z")

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Hi, I wonder how to get confidence intervals for fixed effect parameters \\beta after fitting a LMM using MixedModels.jl? Are Wald-type intervals the only option at the moment? With lme4 in R, I usually use confint(metho…

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## [Slow compile time with a lot of keyword arguments](https://discourse.julialang.org/t/slow-compile-time-with-a-lot-of-keyword-arguments/46677)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 10\
**Last updated:** [September 16, 2020, 7:15pm UTC](https://discourse.julialang.org/t/slow-compile-time-with-a-lot-of-keyword-arguments/46677 "2020-09-16T19:15:28Z")

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Hi! My package PrettyTables.jl started to have a lot of configuration possibilities, which are handle by keyword arguments like: function \_pt\_text(io::IO, pinfo::PrintInfo; border\_crayon::Crayon = Cra…

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## [Poor performance with custom multidimensional iterator](https://discourse.julialang.org/t/poor-performance-with-custom-multidimensional-iterator/46529)

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**Author:** [@benninkrs](https://discourse.julialang.org/u/benninkrs)\
**Replies:** 4\
**Last updated:** [September 16, 2020, 5:48pm UTC](https://discourse.julialang.org/t/poor-performance-with-custom-multidimensional-iterator/46529 "2020-09-16T17:48:22Z")

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I am trying to implement a custom iterator for multidimensional arrays, which among other things, allows one to specify the order in which the axes are iterated. Sadly, I am having trouble getting even close to the perfo…

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## [Dictionary](https://discourse.julialang.org/t/dictionary/46711)

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**Author:** [@mmyousefies](https://discourse.julialang.org/u/mmyousefies)\
**Replies:** 2\
**Last updated:** [September 16, 2020, 4:23pm UTC](https://discourse.julialang.org/t/dictionary/46711 "2020-09-16T16:23:11Z")

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hello, I’m new to Julia, and here’s my problem: using RDatasets, I wanted to make a dictionary of the first 2columns of the “iris” data frame; here’s how I did it: using RDataets IRIS = dataset(“datasets”,“iris”) j …

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## [Reduce and sum Value ( frequency matrix)](https://discourse.julialang.org/t/reduce-and-sum-value-frequency-matrix/46687)

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**Author:** [@JohnFlorez25](https://discourse.julialang.org/u/JohnFlorez25)\
**Replies:** 3\
**Last updated:** [September 16, 2020, 3:35pm UTC](https://discourse.julialang.org/t/reduce-and-sum-value-frequency-matrix/46687 "2020-09-16T15:35:18Z")

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Hello, I have a Dataframe with a frequency matrix generate about events in relation to a user. I need to reduce this matrix in unique USER\_ID and sum each EVENT CATEGORY - events categories correspond to category 1,2…

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## [Iterate with 1:N is faster than 1:length(A)](https://discourse.julialang.org/t/iterate-with-1-n-is-faster-than-1-length-a/46664)

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**Author:** [@stakaz](https://discourse.julialang.org/u/stakaz)\
**Replies:** 12\
**Last updated:** [September 16, 2020, 3:17pm UTC](https://discourse.julialang.org/t/iterate-with-1-n-is-faster-than-1-length-a/46664 "2020-09-16T15:17:43Z")

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Hello, I am about to benchmark different ways of iterate over an array and I have realized a strange thing (I am on julia 1.5.1) The following test: julia\> using BenchmarkTools julia\> function N\_iterator(A, N) …

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## [Suppress non-julia console output](https://discourse.julialang.org/t/suppress-non-julia-console-output/46593)

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**Author:** [@Luapulu](https://discourse.julialang.org/u/Luapulu)\
**Replies:** 10\
**Last updated:** [September 16, 2020, 3:13pm UTC](https://discourse.julialang.org/t/suppress-non-julia-console-output/46593 "2020-09-16T15:13:35Z")

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I’m calling c code from julia, which prints to console when it is run. I’d like to not see these print statements. How do I do that? The Suppressor.@suppress\_out macro doesn’t work in this case.

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## [REPL and for loops (scope behavior change)](https://discourse.julialang.org/t/repl-and-for-loops-scope-behavior-change/13514)

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**Author:** [@saschatimme](https://discourse.julialang.org/u/saschatimme)\
**Replies:** 42\
**Last updated:** [September 16, 2020, 2:57pm UTC](https://discourse.julialang.org/t/repl-and-for-loops-scope-behavior-change/13514 "2020-09-16T14:57:08Z")

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In the REPL, to test some code, I often do things like julia\> a = 0 0 julia\> for i=1:3 a+=i end But under Julia 1.0 this will now throw an error ERROR: UndefVarError: a not defined Stacktrace: \[1\] …

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## [PSA: pin Revise at 2](https://discourse.julialang.org/t/psa-pin-revise-at-2/44412)

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**Author:** [@tim.holy](https://discourse.julialang.org/u/tim.holy)\
**Replies:** 4\
**Last updated:** [September 16, 2020, 2:46pm UTC](https://discourse.julialang.org/t/psa-pin-revise-at-2/44412 "2020-09-16T14:46:52Z")

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Update: now that Revise 3 has been released, this is no longer necessary. Just use fully-updated packages. Several folks are having Revise problems that stem from Pkg installing a very old Revise version. You can fix it…

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## [Variance, std where is now ? in 1.5.1 verision?](https://discourse.julialang.org/t/variance-std-where-is-now-in-1-5-1-verision/46699)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 2\
**Last updated:** [September 16, 2020, 2:41pm UTC](https://discourse.julialang.org/t/variance-std-where-is-now-in-1-5-1-verision/46699 "2020-09-16T14:41:42Z")

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Where in 1.5.1 versio is variance , std ? Version 1.5.1 (2020-08-25) julia\> a = rand(10) 10-element Array{Float64,1}: 0.31820694853200404 0.19056834277810242 0.7491023037833544 0.013571726580821286 0.891972776929…

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## [Why isn't a patch version allowed to narrow supported Julia versions?](https://discourse.julialang.org/t/why-isnt-a-patch-version-allowed-to-narrow-supported-julia-versions/46701)

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**Author:** [@galenlynch](https://discourse.julialang.org/u/galenlynch)\
**Replies:** 10\
**Last updated:** [September 16, 2020, 2:14pm UTC](https://discourse.julialang.org/t/why-isnt-a-patch-version-allowed-to-narrow-supported-julia-versions/46701 "2020-09-16T14:14:24Z")

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I’ve never understood why this rule is enforced in the General registry, e.g. here. If a package changes in no other way than narrowing supported versions of Julia, that is to say that no new functionality is introduced …

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## [Failed to precompile ORCA](https://discourse.julialang.org/t/failed-to-precompile-orca/46494)

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**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 15\
**Last updated:** [September 16, 2020, 2:07pm UTC](https://discourse.julialang.org/t/failed-to-precompile-orca/46494 "2020-09-16T14:07:16Z")

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"’ using Plots,PlotlyJS x=\[1:10\] y=rand(10) z=rand(10) plot(x,y,z) plotlyjs() ‘’’ Error:Failed to precompile ORCA \[47be7bcc-f1a6-5447-8b36-7eeeff7534fd\] to C:\\Users\\zlq.juliapro\\JuliaPro\_v1.4.2-1\\compiled\\v1.4\\OR…

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## [Change parameters in a model in specific time with DifferentialEquations](https://discourse.julialang.org/t/change-parameters-in-a-model-in-specific-time-with-differentialequations/36930)

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**Author:** [@askery](https://discourse.julialang.org/u/askery)\
**Replies:** 8\
**Last updated:** [September 16, 2020, 11:50am UTC](https://discourse.julialang.org/t/change-parameters-in-a-model-in-specific-time-with-differentialequations/36930 "2020-09-16T11:50:08Z")

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Guys, I am really new to Julia. I came to solve a system of ODE and want to stay. For sure my question is trivial, but I looked for similar solutions and could not find for 3 days. Suppose I am solving Lorentz equations…

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## [Interpolating into a series of matrices](https://discourse.julialang.org/t/interpolating-into-a-series-of-matrices/46635)

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**Author:** [@Raf](https://discourse.julialang.org/u/Raf)\
**Replies:** 9\
**Last updated:** [September 16, 2020, 11:06am UTC](https://discourse.julialang.org/t/interpolating-into-a-series-of-matrices/46635 "2020-09-16T11:06:09Z")

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I’m writing a package that needs to generically interpolate a matrix from a time-series of matrices. For example, maybe it’s a series of spatial matrices of monthly mean values, that I would like to interpolate to a sin…

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## [Julia 1.5, error with JuliaInterpreter but it is not installed](https://discourse.julialang.org/t/julia-1-5-error-with-juliainterpreter-but-it-is-not-installed/46644)

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**Author:** [@Olivier\_Merchiers](https://discourse.julialang.org/u/Olivier_Merchiers)\
**Replies:** 5\
**Last updated:** [September 16, 2020, 9:42am UTC](https://discourse.julialang.org/t/julia-1-5-error-with-juliainterpreter-but-it-is-not-installed/46644 "2020-09-16T09:42:50Z")

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Hello everyone, I have this weird error when loading one of my packages in Julia 1.5. In 1.4, there is no issue at all: Error: evaluation error starting at /home/omerchiers/Documents/Travail/02-Recherche/Informatique/D…

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## [Trouble Pre-allocating Outputs](https://discourse.julialang.org/t/trouble-pre-allocating-outputs/39610)

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**Author:** [@loki](https://discourse.julialang.org/u/loki)\
**Replies:** 9\
**Last updated:** [September 16, 2020, 3:30am UTC](https://discourse.julialang.org/t/trouble-pre-allocating-outputs/39610 "2020-09-16T03:30:26Z")

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Hello, I was hoping to get some advice regarding how to properly go about Pre-allocating outputs for a more complicated example and speeding a function. I’ve read through others’ posts and the performance guide but was s…

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## [Status for stacked environments](https://discourse.julialang.org/t/status-for-stacked-environments/18558)

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**Author:** [@krcools](https://discourse.julialang.org/u/krcools)\
**Replies:** 3\
**Last updated:** [September 16, 2020, 2:17am UTC](https://discourse.julialang.org/t/status-for-stacked-environments/18558 "2020-09-16T02:17:46Z")

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Is there a way to make pkg\>status show all packages available in the LOAD\_PATH stack as opposed to only those added to the topmost environment?

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## [Derivative with terminate callback](https://discourse.julialang.org/t/derivative-with-terminate-callback/46409)

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**Author:** [@colinclout12](https://discourse.julialang.org/u/colinclout12)\
**Replies:** 6\
**Last updated:** [September 15, 2020, 8:47pm UTC](https://discourse.julialang.org/t/derivative-with-terminate-callback/46409 "2020-09-15T20:47:16Z")

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I’d like to program a differential equation that runs till it reaches a particular state (e.g. one of the space variables is zero), and then train the some parameters that define the equation so the system reaches the te…

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## [Cannot load SVG files with Gtk.jl](https://discourse.julialang.org/t/cannot-load-svg-files-with-gtk-jl/46655)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 0\
**Last updated:** [September 15, 2020, 7:03pm UTC](https://discourse.julialang.org/t/cannot-load-svg-files-with-gtk-jl/46655 "2020-09-15T19:03:14Z")

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When loading a svg image inside a GtkImage widget, I get a “missing image” icon. If I load the image from within a Glade UI I also get an error message. (julia:18273): Gtk-WARNING \*\*: 21:00:53.077: Could not load image …

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## [Optimizing concatenation of data from large number of files](https://discourse.julialang.org/t/optimizing-concatenation-of-data-from-large-number-of-files/46617)

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**Author:** [@lwhitefox](https://discourse.julialang.org/u/lwhitefox)\
**Replies:** 2\
**Last updated:** [September 15, 2020, 5:05pm UTC](https://discourse.julialang.org/t/optimizing-concatenation-of-data-from-large-number-of-files/46617 "2020-09-15T17:05:26Z")

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I am trying to create a large data array from data in many input files by reading in the individual data file arrays concatenating a subset of columns to generate a large, single array The problem is that it is blazin…

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## [Coordinate transformation from three known points](https://discourse.julialang.org/t/coordinate-transformation-from-three-known-points/37153)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 18\
**Last updated:** [September 15, 2020, 4:07pm UTC](https://discourse.julialang.org/t/coordinate-transformation-from-three-known-points/37153 "2020-09-15T16:07:37Z")

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I have 3 coordinates, moving\_points. I know where each of these is supposed to really be, fixed\_points. I want to transform them (and many other coordinates) to these known locations (involving translation, rotation, but…

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## [Accessing multi-dimensional arrays in 1 go](https://discourse.julialang.org/t/accessing-multi-dimensional-arrays-in-1-go/46641)

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**Author:** [@danicaratelli](https://discourse.julialang.org/u/danicaratelli)\
**Replies:** 5\
**Last updated:** [September 15, 2020, 3:46pm UTC](https://discourse.julialang.org/t/accessing-multi-dimensional-arrays-in-1-go/46641 "2020-09-15T15:46:48Z")

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I am trying to figure out if there is an easy (and quick) way of accessing elements of a multi-dimensional array according to multi-dimensional array of indices. For example: A = reshape(1:8,2,2,2); indxs = repeat(\[1\],…

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## [ArgumentError: invalid argument #4 to LAPACK call](https://discourse.julialang.org/t/argumenterror-invalid-argument-4-to-lapack-call/46455)

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**Author:** [@PhillipBC](https://discourse.julialang.org/u/PhillipBC)\
**Replies:** 7\
**Last updated:** [September 15, 2020, 3:51pm UTC](https://discourse.julialang.org/t/argumenterror-invalid-argument-4-to-lapack-call/46455 "2020-09-15T15:51:02Z")

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This problem arose using Julia 1.4.2, and I then got version 1.5.1 and the problem is still there. If I create a matrix, then get its eigenvalues, then plot the eigenvalues, then get the eigenvalues again, I get the err…

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## [Gtk standalone application (PackageCompiler) cannot open images](https://discourse.julialang.org/t/gtk-standalone-application-packagecompiler-cannot-open-images/46637)

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**Author:** [@xor0110](https://discourse.julialang.org/u/xor0110)\
**Replies:** 0\
**Last updated:** [September 15, 2020, 1:27pm UTC](https://discourse.julialang.org/t/gtk-standalone-application-packagecompiler-cannot-open-images/46637 "2020-09-15T13:27:48Z")

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I have this Gkt.jl application, and I’m trying to make it stand-alone with PackageCompiler. Right now most functionality seems to work, although I have this problem at startup, when I try to load some images, which do n…

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## [Performance of creating a tuple with a for loop](https://discourse.julialang.org/t/performance-of-creating-a-tuple-with-a-for-loop/46606)

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**Author:** [@dogiv](https://discourse.julialang.org/u/dogiv)\
**Replies:** 26\
**Last updated:** [September 15, 2020, 1:11pm UTC](https://discourse.julialang.org/t/performance-of-creating-a-tuple-with-a-for-loop/46606 "2020-09-15T13:11:33Z")

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I have a function “complement” that takes two tuples of ints and does a simple comparison to generate a third tuple. I would prefer to write it so that it works for any length of tuple, but that kills the performance (10…

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## [Why doesn't Makie show pictures？](https://discourse.julialang.org/t/why-doesnt-makie-show-pictures/46571)

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**Author:** [@zlq178](https://discourse.julialang.org/u/zlq178)\
**Replies:** 3\
**Last updated:** [September 15, 2020, 9:03am UTC](https://discourse.julialang.org/t/why-doesnt-makie-show-pictures/46571 "2020-09-15T09:03:09Z")

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‘’’ using AbstractPlotting,Makie x = \[2 .\* (i/3) .\* cos(i) for i in range(0, stop = 4pi, length = 30)\] y = \[2 .\* (i/3) .\* sin(i) for i in range(0, stop = 4pi, length = 30)\] z = range(0, stop = 5, length = 30) a=mesh…

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## [Unique rows indexes in array](https://discourse.julialang.org/t/unique-rows-indexes-in-array/46588)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 14\
**Last updated:** [September 15, 2020, 7:11am UTC](https://discourse.julialang.org/t/unique-rows-indexes-in-array/46588 "2020-09-15T07:11:46Z")

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julia\> baza2 45805×9 Array{String,2}: "0" "000001" "1" "1" "1" "000002" "" "0" "2" "000002" "" "0" julia\> ia = unique(i -\> baza2\[:,6\]\[i\], 1:length( baza2\[:,6\])) 40378-element Array{Int64,1}…

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