# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1423

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

**Page:** 1424

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## [Best Practice for Initializing an Array Prior to for Loop](https://discourse.julialang.org/t/best-practice-for-initializing-an-array-prior-to-for-loop/48502)

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**Author:** [@highflyer737](https://discourse.julialang.org/u/highflyer737)\
**Replies:** 7\
**Last updated:** [April 16, 2021, 4:32pm UTC](https://discourse.julialang.org/t/best-practice-for-initializing-an-array-prior-to-for-loop/48502 "2021-04-16T16:32:57Z")

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Hello, Is there a best practice for initializing arrays prior to for loops / does it matter? (I’ve seen a few similar posts but I don’t think there’s any that explain the differences, or when you might want to use one m…

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## [The difficult task of comparing supervised models](https://discourse.julialang.org/t/the-difficult-task-of-comparing-supervised-models/59148)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 4:27pm UTC](https://discourse.julialang.org/t/the-difficult-task-of-comparing-supervised-models/59148 "2021-04-16T16:27:29Z")

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I read often blogs or even academic articles that compare different machine learning for a specific tasks, ending up of a ranking based on lower MSE or maximum accuracy for example. These comparisons are done by just ap…

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## [@everywhere everywhere](https://discourse.julialang.org/t/everywhere-everywhere/33811)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 5\
**Last updated:** [April 16, 2021, 4:21pm UTC](https://discourse.julialang.org/t/everywhere-everywhere/33811 "2021-04-16T16:21:44Z")

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I’m using Distributed and pmap together for some fairly standard problems, but I realized that, to get my code to run, I am putting @everywhere on just about every line of code, and I’m trying to see if I can simplify th…

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## [What does this syntax (using .Filename) mean?](https://discourse.julialang.org/t/what-does-this-syntax-using-filename-mean/59420)

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**Author:** [@Thomas](https://discourse.julialang.org/u/Thomas)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 4:04pm UTC](https://discourse.julialang.org/t/what-does-this-syntax-using-filename-mean/59420 "2021-04-16T16:04:51Z")

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Can someone explain this syntax (in REPL)? include("Filename.jl") using .Filename I can sort of understand the first, but what is the . in front of Filename mean?

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## [Differences between mutliple functions and function with multiple methods](https://discourse.julialang.org/t/differences-between-mutliple-functions-and-function-with-multiple-methods/59317)

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**Author:** [@BambOoxX](https://discourse.julialang.org/u/BambOoxX)\
**Replies:** 9\
**Last updated:** [April 16, 2021, 4:01pm UTC](https://discourse.julialang.org/t/differences-between-mutliple-functions-and-function-with-multiple-methods/59317 "2021-04-16T16:01:50Z")

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For one of my projects, I have multiple implementations of the same analytical computations. These implementations offer different speed / precision trade-offs, and involve mostly a two step process where the entries and…

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## [ArchGDAL.jl (or GDAL.jl not sure) - Undesired behaviour when reprojecting coordinates to EPSG 4326](https://discourse.julialang.org/t/archgdal-jl-or-gdal-jl-not-sure-undesired-behaviour-when-reprojecting-coordinates-to-epsg-4326/59415)

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**Author:** [@carlosmolinero](https://discourse.julialang.org/u/carlosmolinero)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 3:24pm UTC](https://discourse.julialang.org/t/archgdal-jl-or-gdal-jl-not-sure-undesired-behaviour-when-reprojecting-coordinates-to-epsg-4326/59415 "2021-04-16T15:24:07Z")

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Hello, I am fairly new to Julia and absolutely new to ArchGDAL, so please excuse me if what I am reporting is actually a misconception on my part. I would like to first thank the developers of both the language and the p…

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## [Julia console code syntax highlight in GitHub?](https://discourse.julialang.org/t/julia-console-code-syntax-highlight-in-github/59389)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 2:58pm UTC](https://discourse.julialang.org/t/julia-console-code-syntax-highlight-in-github/59389 "2021-04-16T14:58:23Z")

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GitHub supports Julia syntax highlighting using “\`\`\`julia”. But how to specify “julia console” syntax highlithing, i.e.when the code includes the Julia prompt ?

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## [Measurements Indicate that this is “Faster than the Speed of Light”](https://discourse.julialang.org/t/measurements-indicate-that-this-is-faster-than-the-speed-of-light/59353)

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**Author:** [@GpuCoder](https://discourse.julialang.org/u/GpuCoder)\
**Replies:** 4\
**Last updated:** [April 16, 2021, 2:52pm UTC](https://discourse.julialang.org/t/measurements-indicate-that-this-is-faster-than-the-speed-of-light/59353 "2021-04-16T14:52:21Z")

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I created a variable of type BitSet and used setdiff! to remove elements from it one at a time until it was empty. This took linear time as a function of the set size and the constant was about 10 cycles per element (on …

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## [Concatenate markdown strings](https://discourse.julialang.org/t/concatenate-markdown-strings/59385)

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**Author:** [@PhilipDLoewen](https://discourse.julialang.org/u/PhilipDLoewen)\
**Replies:** 5\
**Last updated:** [April 16, 2021, 2:43pm UTC](https://discourse.julialang.org/t/concatenate-markdown-strings/59385 "2021-04-16T14:43:30Z")

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For ordinary strings, "as"\*"df" produces "asdf". For markdown strings, md"as"\*md"df" produces an error. So does md\_str("as"\*"df"). Is there any way to reinterpret a string with a complicated history as markdown? Eventua…

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## [Run function with delay](https://discourse.julialang.org/t/run-function-with-delay/59404)

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**Author:** [@Javise](https://discourse.julialang.org/u/Javise)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 2:42pm UTC](https://discourse.julialang.org/t/run-function-with-delay/59404 "2021-04-16T14:42:26Z")

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Hello, How can I make a function run automatically X seconds after another function has been run (with Pluto) ? Thank you

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## [Plots not Compiling with Win 10 & Julia 1.6.0](https://discourse.julialang.org/t/plots-not-compiling-with-win-10-julia-1-6-0/59370)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 2:37pm UTC](https://discourse.julialang.org/t/plots-not-compiling-with-win-10-julia-1-6-0/59370 "2021-04-16T14:37:55Z")

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Today I went to a Pluto notebook that had been working correctly. The notebook suggested that I upgrade to the latest version of Pluto, and once upgraded it complained that Plots would not compile, a problem with GR. I…

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## [What are the rules for qualified/unqualified symbols in macros? (or is it a bug?)](https://discourse.julialang.org/t/what-are-the-rules-for-qualified-unqualified-symbols-in-macros-or-is-it-a-bug/59293)

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**Author:** [@mobius-eng](https://discourse.julialang.org/u/mobius-eng)\
**Replies:** 5\
**Last updated:** [April 16, 2021, 2:20pm UTC](https://discourse.julialang.org/t/what-are-the-rules-for-qualified-unqualified-symbols-in-macros-or-is-it-a-bug/59293 "2021-04-16T14:20:46Z")

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Let’s say I want to automate making lots of very similar looking, but semantically distinct types: macro make\_struct(arg) quote struct $(esc(arg)) x end export $(esc(arg)) end…

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## [Real time timer?](https://discourse.julialang.org/t/real-time-timer/59407)

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**Author:** [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)\
**Replies:** 4\
**Last updated:** [April 16, 2021, 2:19pm UTC](https://discourse.julialang.org/t/real-time-timer/59407 "2021-04-16T14:19:48Z")

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Hello, all. I was wondering if there was a macro out there similar to @time, but that shows the timer update in real time. Anyone know one? The use case is that I’ve got some pretty expensive functions and it would be …

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## [JSON3 filtering a JSON object](https://discourse.julialang.org/t/json3-filtering-a-json-object/59412)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 4\
**Last updated:** [April 16, 2021, 1:20pm UTC](https://discourse.julialang.org/t/json3-filtering-a-json-object/59412 "2021-04-16T13:20:14Z")

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How can I do this? using JSON3 json = """ { "type": "FeatureCollection", "features": \[ {"type":"Feature","geometry":{"type":"Polygon","coordinates":\[\[\[-120.8519857235256,49.00031611973458\],\[-121.7597100…

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## [Feedback on Julia User & Developer Survey 2021](https://discourse.julialang.org/t/feedback-on-julia-user-developer-survey-2021/58927)

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**Author:** [@ahclaster](https://discourse.julialang.org/u/ahclaster)\
**Replies:** 7\
**Last updated:** [April 16, 2021, 1:11pm UTC](https://discourse.julialang.org/t/feedback-on-julia-user-developer-survey-2021/58927 "2021-04-16T13:11:55Z")

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It’s time to conduct the third annual Julia User & Developer survey. Before we invite Julia users and developers to complete the survey, we invite you to review the survey questions and share any feedback you may have. T…

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## [DifferentialEquations.jl: running out of memory with large system size ODE](https://discourse.julialang.org/t/differentialequations-jl-running-out-of-memory-with-large-system-size-ode/59357)

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**Author:** [@Joh11](https://discourse.julialang.org/u/Joh11)\
**Replies:** 11\
**Last updated:** [April 16, 2021, 10:53am UTC](https://discourse.julialang.org/t/differentialequations-jl-running-out-of-memory-with-large-system-size-ode/59357 "2021-04-16T10:53:59Z")

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Hi everyone, I need to solve a first order, homogeneous, time independent ODE on a relatively big system size (3 \\times 3 \\times 144 \\times 144=186,624 dimensions). I had previously made a crude fixed step Dormand Princ…

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## [NeuralPDE/PINN: System of Equations Substitution and Inequalities](https://discourse.julialang.org/t/neuralpde-pinn-system-of-equations-substitution-and-inequalities/59379)

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**Author:** [@James\_Gorman](https://discourse.julialang.org/u/James_Gorman)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 8:57am UTC](https://discourse.julialang.org/t/neuralpde-pinn-system-of-equations-substitution-and-inequalities/59379 "2021-04-16T08:57:41Z")

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After stumbling across physics-informed neural networks a couple weeks ago, and realizing julia had a framework for solving them, I realized I might have found an open-source method for solving PDEs that was powerful and…

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## [Precompiling most packages fails in Atom/Juno with 1.6.0](https://discourse.julialang.org/t/precompiling-most-packages-fails-in-atom-juno-with-1-6-0/59308)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 12\
**Last updated:** [April 16, 2021, 6:24am UTC](https://discourse.julialang.org/t/precompiling-most-packages-fails-in-atom-juno-with-1-6-0/59308 "2021-04-16T06:24:01Z")

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I wish I could narrow down the problem more precisely than this, but since updating to 1.6.0, I have begun to encounter very strange behavior when calling using Polyhedra (and various other packages) from the REPL embedd…

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## [Does @allocated not work with multithreading?](https://discourse.julialang.org/t/does-allocated-not-work-with-multithreading/59354)

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**Author:** [@nmayhall-vt](https://discourse.julialang.org/u/nmayhall-vt)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 5:12am UTC](https://discourse.julialang.org/t/does-allocated-not-work-with-multithreading/59354 "2021-04-16T05:12:38Z")

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I’ve been trying to better undertstand how to find allocations in my code, and I stumbled on this simple MWE which either exposes some limitation of @allocated, or (more likely) a limitation of my understanding. functio…

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## [Syntax error](https://discourse.julialang.org/t/syntax-error/59378)

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**Author:** [@trodger88](https://discourse.julialang.org/u/trodger88)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 1:42am UTC](https://discourse.julialang.org/t/syntax-error/59378 "2021-04-16T01:42:42Z")

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Using Gtk b=GtkBuilder(filename=“/home/tjr/Glade/test.glade”) win=b\[“Test Window”\] showall(win) When I try to run I get syntax: extra token “Gtk” after end of expression top-level scope at test.jl:1 include\_string…

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## [\[CFP\] Parallel Applications Workshop, Alternative to MPI+x -- Supercomputing 2021](https://discourse.julialang.org/t/cfp-parallel-applications-workshop-alternative-to-mpi-x-supercomputing-2021/59358)

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**Author:** [@vchuravy](https://discourse.julialang.org/u/vchuravy)\
**Replies:** 0\
**Last updated:** [April 15, 2021, 4:38pm UTC](https://discourse.julialang.org/t/cfp-parallel-applications-workshop-alternative-to-mpi-x-supercomputing-2021/59358 "2021-04-15T16:38:41Z")

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Call for Papers PAW-ATM 2021: Parallel Applications Workshop, Alternatives To MPI+X Held in conjunction with SC21, St. Louis, MO http://sourceryinstitute.github.io/PA…

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## [Manipulation of dataframe rows upon repeated values in a given column](https://discourse.julialang.org/t/manipulation-of-dataframe-rows-upon-repeated-values-in-a-given-column/59367)

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**Author:** [@mocalvao](https://discourse.julialang.org/u/mocalvao)\
**Replies:** 5\
**Last updated:** [April 15, 2021, 11:23pm UTC](https://discourse.julialang.org/t/manipulation-of-dataframe-rows-upon-repeated-values-in-a-given-column/59367 "2021-04-15T23:23:57Z")

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I have the following dataframe (in fact, part of a much larger dataframe, where the Key’s repeat arbitrarily, sometimes even more than twice): df\_ini = DataFrame( Key = \[170, 447, 447, 699, 963, 963, 963, 756\], Type = …

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## [Mapping with Flattening - Like a Kronecker Product](https://discourse.julialang.org/t/mapping-with-flattening-like-a-kronecker-product/59141)

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**Author:** [@GpuCoder](https://discourse.julialang.org/u/GpuCoder)\
**Replies:** 7\
**Last updated:** [April 15, 2021, 8:42pm UTC](https://discourse.julialang.org/t/mapping-with-flattening-like-a-kronecker-product/59141 "2021-04-15T20:42:54Z")

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I want to do something like A = map(x -\> \[x,2\*x\], transpose(\[1,2,3\])) which yields: 1×3 transpose(::Vector{LinearAlgebra.Transpose{Int64, Vector{Int64}}}) with eltype Vector{Int64}: \[1, 2\] \[2, 4\] \[3, 6\] But I want…

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## [Use of Timer](https://discourse.julialang.org/t/use-of-timer/59350)

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**Author:** [@Javise](https://discourse.julialang.org/u/Javise)\
**Replies:** 3\
**Last updated:** [April 15, 2021, 8:14pm UTC](https://discourse.julialang.org/t/use-of-timer/59350 "2021-04-15T20:14:13Z")

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Hello, I would like to make a text appear and have each letter appear at X seconds intervals. I think it is possible to do this with the Timer function but I don’t know how to use it. I had thought of using an array tha…

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## [\[ANN\] PrettyTables.jl v0.12](https://discourse.julialang.org/t/ann-prettytables-jl-v0-12/59130)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 8\
**Last updated:** [April 15, 2021, 8:14pm UTC](https://discourse.julialang.org/t/ann-prettytables-jl-v0-12/59130 "2021-04-15T20:14:00Z")

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Hi! I just released PrettyTables.jl v0.12. As I mentioned in my last post, it has some deprecations (nothing is breaking) because two things: The backend is now selected using Val instead of a symbol. Hence, backend =…

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## [A partition and a crossValidation function over arbitrary number of n-dimensional arrays](https://discourse.julialang.org/t/a-partition-and-a-crossvalidation-function-over-arbitrary-number-of-n-dimensional-arrays/59343)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 0\
**Last updated:** [April 15, 2021, 1:50pm UTC](https://discourse.julialang.org/t/a-partition-and-a-crossvalidation-function-over-arbitrary-number-of-n-dimensional-arrays/59343 "2021-04-15T13:50:15Z")

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Hello, for my own machine learning library, I implemented the following functions to partition and run cross-validation over a m-set of n-dimensional arrays, where one can specify the dimension to partition or run the cr…

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## [MbedTLS 1.0.2 failed to load on Julia 1.5.2 (solved by downgrading to MbedTLS 0.7.0)](https://discourse.julialang.org/t/mbedtls-1-0-2-failed-to-load-on-julia-1-5-2-solved-by-downgrading-to-mbedtls-0-7-0/47430)

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**Author:** [@awasserman](https://discourse.julialang.org/u/awasserman)\
**Replies:** 7\
**Last updated:** [April 15, 2021, 7:17pm UTC](https://discourse.julialang.org/t/mbedtls-1-0-2-failed-to-load-on-julia-1-5-2-solved-by-downgrading-to-mbedtls-0-7-0/47430 "2021-04-15T19:17:32Z")

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I had an issue with installing a few packages that ultimately depended on MbedTLS (via HTTP). Adding and building MbedTLS 1.0.2 seemed to work fine, but while precompiling it raised the following error with undefined s…

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## [Problem in understanding how to load data to estimate covariance matrix](https://discourse.julialang.org/t/problem-in-understanding-how-to-load-data-to-estimate-covariance-matrix/59365)

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**Author:** [@Shahal](https://discourse.julialang.org/u/Shahal)\
**Replies:** 2\
**Last updated:** [April 15, 2021, 6:06pm UTC](https://discourse.julialang.org/t/problem-in-understanding-how-to-load-data-to-estimate-covariance-matrix/59365 "2021-04-15T18:06:40Z")

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0 My aim is to estimate the covariance matrix using 10 Forex high-frequency data. I found the Julia package, HighFrequencyCovariance, HighFrequencyCovariance.jl - Algorithms for efficiently estimating covariance matric…

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## [How do model a sub type that can fall under two different abstract types?](https://discourse.julialang.org/t/how-do-model-a-sub-type-that-can-fall-under-two-different-abstract-types/59355)

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**Author:** [@anon60034542](https://discourse.julialang.org/u/anon60034542)\
**Replies:** 2\
**Last updated:** [April 15, 2021, 4:31pm UTC](https://discourse.julialang.org/t/how-do-model-a-sub-type-that-can-fall-under-two-different-abstract-types/59355 "2021-04-15T16:31:45Z")

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Suppose you’re building a medieval role playing game, you’re going to have weapons of different types, so you’ll create an abstract type called Weapon: abstract type GameObject end abstract type Weapon \<: GameObject end…

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## [Gadfly and controling colors and label](https://discourse.julialang.org/t/gadfly-and-controling-colors-and-label/59290)

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**Author:** [@Oto\_Brzobohaty](https://discourse.julialang.org/u/Oto_Brzobohaty)\
**Replies:** 9\
**Last updated:** [April 15, 2021, 4:15pm UTC](https://discourse.julialang.org/t/gadfly-and-controling-colors-and-label/59290 "2021-04-15T16:15:25Z")

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I like the syntax of plotting using Gadfly, but it is relatively far from my experience with plotting with Matlab and Plots. I wonder if there is an easy way how to control the colors and labels in the following example…

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