# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1896

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

**Page:** 1897

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## [Cannot install PiecewiseLinearOpt package](https://discourse.julialang.org/t/cannot-install-piecewiselinearopt-package/30170)

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**Author:** [@kfurmanska](https://discourse.julialang.org/u/kfurmanska)\
**Replies:** 1\
**Last updated:** [October 24, 2019, 10:01am UTC](https://discourse.julialang.org/t/cannot-install-piecewiselinearopt-package/30170 "2019-10-24T10:01:18Z")

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I try to install PiecewiseLinearOpt package, but it gets into conflict with other Julia packages. Firstly, it highlighed JuMP: julia\> Pkg.add("PiecewiseLinearOpt") Resolving package versions... ERROR: Unsatisfiable req…

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## [Findall slow](https://discourse.julialang.org/t/findall-slow/30247)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 8\
**Last updated:** [October 24, 2019, 8:26am UTC](https://discourse.julialang.org/t/findall-slow/30247 "2019-10-24T08:26:28Z")

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Hello, I would like to find indices of a 1D array wich verify a given condition. I think that the way to go is to use the function findall. However I have found this tricky way to be actually faster and has way less mem…

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## [Julia Bloggers is 404ing](https://discourse.julialang.org/t/julia-bloggers-is-404ing/30261)

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**Author:** [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Replies:** 1\
**Last updated:** [October 24, 2019, 7:38am UTC](https://discourse.julialang.org/t/julia-bloggers-is-404ing/30261 "2019-10-24T07:38:37Z")

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clicking the link on the Julia website (https://www.juliabloggers.com/public\_html/) gives a page not found error currently.

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## [How to filter out rows with NaN in specific fields?](https://discourse.julialang.org/t/how-to-filter-out-rows-with-nan-in-specific-fields/30250)

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**Author:** [@abe](https://discourse.julialang.org/u/abe)\
**Replies:** 2\
**Last updated:** [October 24, 2019, 5:35am UTC](https://discourse.julialang.org/t/how-to-filter-out-rows-with-nan-in-specific-fields/30250 "2019-10-24T05:35:16Z")

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This seems like a pretty basic operation, but I’m having difficulty figuring it out. In dplyr I’d do something like filtering based on !is.na(my\_field), but I’m not sure what the equivalent Julia/DataFramesMeta is. I hav…

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## [Factorize() on Symmetric types does not try cholesky()](https://discourse.julialang.org/t/factorize-on-symmetric-types-does-not-try-cholesky/30177)

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**Author:** [@SEA](https://discourse.julialang.org/u/SEA)\
**Replies:** 9\
**Last updated:** [October 24, 2019, 5:02am UTC](https://discourse.julialang.org/t/factorize-on-symmetric-types-does-not-try-cholesky/30177 "2019-10-24T05:02:09Z")

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factorize() on a dense matrix tests several properties to find an efficient factorization. If factorize is called on Symmetric or Hermitian types, it does not try cholesky(), but only considers bunchkaufman(): From the s…

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## [IndexedTables and type-stability of IndexedTables.groupby](https://discourse.julialang.org/t/indexedtables-and-type-stability-of-indexedtables-groupby/30186)

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**Author:** [@bashonubuntu](https://discourse.julialang.org/u/bashonubuntu)\
**Replies:** 9\
**Last updated:** [October 24, 2019, 12:43am UTC](https://discourse.julialang.org/t/indexedtables-and-type-stability-of-indexedtables-groupby/30186 "2019-10-24T00:43:01Z")

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Hi, I am a bit confused by IndexedTable being referred to as a “type-stable” alternative to DataFrames. If I write a function which does some operations and returns an IndexedTable, the @code\_warntype still flags the In…

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## [Why to assign a lot of variants to one array? (Basic syntax)](https://discourse.julialang.org/t/why-to-assign-a-lot-of-variants-to-one-array-basic-syntax/30253)

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**Author:** [@Yan](https://discourse.julialang.org/u/Yan)\
**Replies:** 1\
**Last updated:** [October 24, 2019, 12:40am UTC](https://discourse.julialang.org/t/why-to-assign-a-lot-of-variants-to-one-array-basic-syntax/30253 "2019-10-24T00:40:02Z")

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a=b=c=\[0\] x=y=z=0 Why producing different meanings behind a similar basic syntax? despite one for immutable, another for mutable.

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## [Preventing dispatch on val not bits](https://discourse.julialang.org/t/preventing-dispatch-on-val-not-bits/27911)

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**Author:** [@o314](https://discourse.julialang.org/u/o314)\
**Replies:** 5\
**Last updated:** [October 23, 2019, 10:55pm UTC](https://discourse.julialang.org/t/preventing-dispatch-on-val-not-bits/27911 "2019-10-23T22:55:58Z")

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Val is mainly use to dispatch on bits type with static optimization. It’s rather simple to do a coding error and dispatch on Val(:foo) that is not a bits type instance. Is it possible that the compiler emits a warning …

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## [How can we encourage Julia package developers to release version 1.0.0?](https://discourse.julialang.org/t/how-can-we-encourage-julia-package-developers-to-release-version-1-0-0/29124)

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**Author:** [@dilumaluthge](https://discourse.julialang.org/u/dilumaluthge)\
**Replies:** 34\
**Last updated:** [October 23, 2019, 9:47pm UTC](https://discourse.julialang.org/t/how-can-we-encourage-julia-package-developers-to-release-version-1-0-0/29124 "2019-10-23T21:47:38Z")

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For the overwhelming majority of Julia packages registered in the General registry, the latest release of the package has version of the form 0.X.Y. (See the table at the bottom of this post.) As the Julia ecosystem con…

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## [Saving only part of the solution in DifferentialEquations.jl](https://discourse.julialang.org/t/saving-only-part-of-the-solution-in-differentialequations-jl/30134)

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**Author:** [@LolianSh](https://discourse.julialang.org/u/LolianSh)\
**Replies:** 6\
**Last updated:** [October 23, 2019, 8:28pm UTC](https://discourse.julialang.org/t/saving-only-part-of-the-solution-in-differentialequations-jl/30134 "2019-10-23T20:28:41Z")

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I want to use DifferentialEquations.jl to solve a system of stochastic time dependent PDEs, with a complicated geometry (multiple extended variables occupying different geometries, 1D+2D or 2D+3D, in the same simulation)…

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## [Julia in production: examples and share your experience](https://discourse.julialang.org/t/julia-in-production-examples-and-share-your-experience/30223)

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**Author:** [@jair\_wuilloud](https://discourse.julialang.org/u/jair_wuilloud)\
**Replies:** 7\
**Last updated:** [October 23, 2019, 7:45pm UTC](https://discourse.julialang.org/t/julia-in-production-examples-and-share-your-experience/30223 "2019-10-23T19:45:23Z")

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I am looking for examples of Julia successfully implemented IN PRODUCTION. Can somebody point me at examples or share positive/negative experience with Julia in Prod.?

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## [Old procedure guy](https://discourse.julialang.org/t/old-procedure-guy/30226)

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**Author:** [@wcostrino](https://discourse.julialang.org/u/wcostrino)\
**Replies:** 6\
**Last updated:** [October 23, 2019, 4:49pm UTC](https://discourse.julialang.org/t/old-procedure-guy/30226 "2019-10-23T16:49:38Z")

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Hello, community. I am trying to convert myself from old procedures and shells programming to Julia. I am strugling to learn objects and the Julia paradigm but a lot of old habits come across. So, I developed a progra…

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## [Type promototion of Vectors](https://discourse.julialang.org/t/type-promototion-of-vectors/30227)

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**Author:** [@mtfishman](https://discourse.julialang.org/u/mtfishman)\
**Replies:** 6\
**Last updated:** [October 23, 2019, 4:09pm UTC](https://discourse.julialang.org/t/type-promototion-of-vectors/30227 "2019-10-23T16:09:23Z")

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I believe this might be considered a bug in type promotion, but I wanted to ask here first before reporting an issue. In Julia v1.2.0 and v1.3.0-rc4.1, I see the following behavior: julia\> promote\_type(ComplexF64,Float3…

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## [How to do \`select\` on channels like go(\`alts\` in clojure)?](https://discourse.julialang.org/t/how-to-do-select-on-channels-like-go-alts-in-clojure/30176)

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**Author:** [@isaactsang](https://discourse.julialang.org/u/isaactsang)\
**Replies:** 2\
**Last updated:** [October 23, 2019, 4:14pm UTC](https://discourse.julialang.org/t/how-to-do-select-on-channels-like-go-alts-in-clojure/30176 "2019-10-23T16:14:25Z")

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And then function take! should have a timeout parameter. take!(channel, timeout=1000)

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## [Learning Julia: Writing a onehot encoder](https://discourse.julialang.org/t/learning-julia-writing-a-onehot-encoder/30215)

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**Author:** [@Sam\_Johnson](https://discourse.julialang.org/u/Sam_Johnson)\
**Replies:** 5\
**Last updated:** [October 23, 2019, 2:58pm UTC](https://discourse.julialang.org/t/learning-julia-writing-a-onehot-encoder/30215 "2019-10-23T14:58:36Z")

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Hello fellow Julia coders. I’m relatively new to Julia and one of the first things I like to do is translate another script into my new working language. I was working on a simple machine learning project with the Kaggle…

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## [Error when evaluating \`missing\` in Juno](https://discourse.julialang.org/t/error-when-evaluating-missing-in-juno/30219)

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**Author:** [@fratrik](https://discourse.julialang.org/u/fratrik)\
**Replies:** 1\
**Last updated:** [October 23, 2019, 2:20pm UTC](https://discourse.julialang.org/t/error-when-evaluating-missing-in-juno/30219 "2019-10-23T14:20:11Z")

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In Juno/Atom. If I use ctrl-enter to evaluate missing in a .jl file, I get a Julia Client - Internal Error Blockquote TypeError: non-boolean (Missing) used in boolean context (::getfield(Atom, Symbol(“##117#122”)){S…

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## [Get route length 0 wile trying to caculate route between two given locations using package OpenStreetMapX](https://discourse.julialang.org/t/get-route-length-0-wile-trying-to-caculate-route-between-two-given-locations-using-package-openstreetmapx/30220)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 0\
**Last updated:** [October 23, 2019, 1:53pm UTC](https://discourse.julialang.org/t/get-route-length-0-wile-trying-to-caculate-route-between-two-given-locations-using-package-openstreetmapx/30220 "2019-10-23T13:53:02Z")

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I have two locations with latitude and longitude pair as the following: loc1 = (35.96395340992261,25.08696560352753) loc2 = (69.37249071020585,35.60655488064029) Openstreetmap data is obtained from the link: GEOFABRIK…

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## [Learning Julia: Splitting passenger titles into separate attributes for Titanic passengers with split and Array comprehension](https://discourse.julialang.org/t/learning-julia-splitting-passenger-titles-into-separate-attributes-for-titanic-passengers-with-split-and-array-comprehension/30218)

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**Author:** [@Sam\_Johnson](https://discourse.julialang.org/u/Sam_Johnson)\
**Replies:** 0\
**Last updated:** [October 23, 2019, 12:35pm UTC](https://discourse.julialang.org/t/learning-julia-splitting-passenger-titles-into-separate-attributes-for-titanic-passengers-with-split-and-array-comprehension/30218 "2019-10-23T12:35:40Z")

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The Kaggle Titanic machine learning competition is a great starter project. Before getting to the actual categorical modeling–will this passenger survive or not?–there’s some work to be done to get the data ready to find…

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## [Example for using Interact.tabs](https://discourse.julialang.org/t/example-for-using-interact-tabs/30216)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 0\
**Last updated:** [October 23, 2019, 12:15pm UTC](https://discourse.julialang.org/t/example-for-using-interact-tabs/30216 "2019-10-23T12:15:41Z")

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Does any one have some example where they use Interact.tabs ? I’m mainly looking for some example where tabs is used to switch between “pages”, like a web-browser (and adding new tabs by pressing on the + tab). Thanks!

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## [Did anyone thought of implementing Octave on top of Julia?](https://discourse.julialang.org/t/did-anyone-thought-of-implementing-octave-on-top-of-julia/30211)

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**Author:** [@XVilka](https://discourse.julialang.org/u/XVilka)\
**Replies:** 3\
**Last updated:** [October 23, 2019, 11:35am UTC](https://discourse.julialang.org/t/did-anyone-thought-of-implementing-octave-on-top-of-julia/30211 "2019-10-23T11:35:40Z")

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Apparently, a lot of the Octave/MATLAB features are already available in Julia, and implementing Octave language interpreter would allow to save a lot of time for both worlds. So basically, it will boil down to implement…

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## [Strange behavior of Debugger, Atom, Julia code?](https://discourse.julialang.org/t/strange-behavior-of-debugger-atom-julia-code/30207)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 1\
**Last updated:** [October 23, 2019, 9:22am UTC](https://discourse.julialang.org/t/strange-behavior-of-debugger-atom-julia-code/30207 "2019-10-23T09:22:27Z")

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I was wondering, does anyone experience something strange like what I encountered currently. Code: using OpenStreetMapX using Debugger @enter OpenStreetMapX.get\_map\_data("/home/Desktop/s.osm") println("haha") Then, R…

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## [Explicit version ranges in compat section in Project.toml?](https://discourse.julialang.org/t/explicit-version-ranges-in-compat-section-in-project-toml/30147)

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**Author:** [@oschulz](https://discourse.julialang.org/u/oschulz)\
**Replies:** 12\
**Last updated:** [October 23, 2019, 8:37am UTC](https://discourse.julialang.org/t/explicit-version-ranges-in-compat-section-in-project-toml/30147 "2019-10-23T08:37:29Z")

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Is it possible to specify an explicit version range in the \[compat\] section of a “Project.toml” file? To prevent resolution failure among several packages with inter-dependencies, while also satisfying the new rules for …

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## [How to exclude the columns of a matrix which are present as columns in another matrix](https://discourse.julialang.org/t/how-to-exclude-the-columns-of-a-matrix-which-are-present-as-columns-in-another-matrix/30206)

<div class="topic-metadata">

**Author:** [@Ujku\_KU](https://discourse.julialang.org/u/Ujku_KU)\
**Replies:** 2\
**Last updated:** [October 23, 2019, 8:30am UTC](https://discourse.julialang.org/t/how-to-exclude-the-columns-of-a-matrix-which-are-present-as-columns-in-another-matrix/30206 "2019-10-23T08:30:05Z")

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Hi guys, is there any existing function/method in Julia which checks if the columns of a matrix are columns of another matrix, and remove them from one of the matrices in case there is a positive outcome? Thank you ver…

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## [Bad performance of group\_by of DataFrames - updated -](https://discourse.julialang.org/t/bad-performance-of-group-by-of-dataframes-updated/30061)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 21\
**Last updated:** [October 23, 2019, 8:24am UTC](https://discourse.julialang.org/t/bad-performance-of-group-by-of-dataframes-updated/30061 "2019-10-23T08:24:08Z")

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Hello, I am working on a small dataset with 30 rows and 19 columns. I do a group\_by on 3 colums and aggregate between one and all colums, using sum or maximum as aggregation functions. The number of colums that are q…

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## [Data structures for threaded computing](https://discourse.julialang.org/t/data-structures-for-threaded-computing/30131)

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**Author:** [@dataDiver](https://discourse.julialang.org/u/dataDiver)\
**Replies:** 23\
**Last updated:** [October 23, 2019, 7:32am UTC](https://discourse.julialang.org/t/data-structures-for-threaded-computing/30131 "2019-10-23T07:32:25Z")

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I have noticed that I am not getting the correct multiple speedups I should be getting when using threads in Julia v1.3 rc4 for what are essentially independent calculations. When I try breaking up the matrices into arra…

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## [Performance of Comprehensions versus For Loops](https://discourse.julialang.org/t/performance-of-comprehensions-versus-for-loops/30066)

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**Author:** [@jbu](https://discourse.julialang.org/u/jbu)\
**Replies:** 7\
**Last updated:** [October 23, 2019, 5:45am UTC](https://discourse.julialang.org/t/performance-of-comprehensions-versus-for-loops/30066 "2019-10-23T05:45:36Z")

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Is there any significant performance difference between comprehensions and equivalent for loops for constructing arrays? Similarly, is there any reason to prefer one over the other in terms of performance? The documentat…

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## [Tensor product inside function](https://discourse.julialang.org/t/tensor-product-inside-function/30197)

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**Author:** [@Veenty](https://discourse.julialang.org/u/Veenty)\
**Replies:** 1\
**Last updated:** [October 23, 2019, 5:05am UTC](https://discourse.julialang.org/t/tensor-product-inside-function/30197 "2019-10-23T05:05:59Z")

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So I have the following code function CC\_trap(X::Array{Float64,2}, tag::Int64) a = 0.0 for i=1:size(X)\[1\] for j=1:size(X)\[2\] global a += weights\_CC\[i\]\*X\[i,j\] end end a = result\_i…

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## [Opportunity in Melbourne Australia](https://discourse.julialang.org/t/opportunity-in-melbourne-australia/30200)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [October 22, 2019, 11:02pm UTC](https://discourse.julialang.org/t/opportunity-in-melbourne-australia/30200 "2019-10-22T23:02:53Z")

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https://www.pi.exchange/careers/product-data-scientist-melbourne We don’t use Julia yet but we are open to using Julia. In fact, I am actively exploring the use of Julia in helping to compute statistics on datasets with…

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## [Segfault when calling library function that works correctly standalone](https://discourse.julialang.org/t/segfault-when-calling-library-function-that-works-correctly-standalone/30189)

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**Author:** [@Mikhail\_Kagalenko](https://discourse.julialang.org/u/Mikhail_Kagalenko)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 9:34pm UTC](https://discourse.julialang.org/t/segfault-when-calling-library-function-that-works-correctly-standalone/30189 "2019-10-22T21:34:47Z")

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So there’s this very basic example of finding the roots of unity using the MPSolve library. Calling from C void test\_mps(void); int main(void) { test\_mps(); return 0; } gives the correct results and passes valgrin…

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## [Vcat list of dataframes in for loop](https://discourse.julialang.org/t/vcat-list-of-dataframes-in-for-loop/30188)

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**Author:** [@FredC](https://discourse.julialang.org/u/FredC)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 9:14pm UTC](https://discourse.julialang.org/t/vcat-list-of-dataframes-in-for-loop/30188 "2019-10-22T21:14:56Z")

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I’m attempting something like out = DataFrame() for f in readdir(“csvs”) vcat(out,CSV.read(f)) end out is empty at the end of the for loop even though everything seems to be working. Context is that I’m trying to memo…

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