# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1998

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

**Page:** 1999

---

## [Introduction to Julia (Julia Academy): Where loop issue](https://discourse.julialang.org/t/introduction-to-julia-julia-academy-where-loop-issue/24058)

<div class="topic-metadata">

**Author:** [@taqtiqa-mark](https://discourse.julialang.org/u/taqtiqa-mark)\
**Replies:** 0\
**Last updated:** [May 10, 2019, 3:06am UTC](https://discourse.julialang.org/t/introduction-to-julia-julia-academy-where-loop-issue/24058 "2019-05-10T03:06:19Z")

</div>

Hi, Thanks for putting together the Introduction to Julia (Julia Academy) videos and notebooks. Working through the video’s I was using a Julia terminal-REPL session, and bumped into the global/local variable issue whe…

---

## [Redirect stderr/out to IOBuffer()](https://discourse.julialang.org/t/redirect-stderr-out-to-iobuffer/23984)

<div class="topic-metadata">

**Author:** [@Pbellive](https://discourse.julialang.org/u/Pbellive)\
**Replies:** 6\
**Last updated:** [May 10, 2019, 2:59am UTC](https://discourse.julialang.org/t/redirect-stderr-out-to-iobuffer/23984 "2019-05-10T02:59:59Z")

</div>

I have a Julia script that runs on a remote machine. The main julia process running this script launches local julia worker processes and waits for AMQP messages that contain input data for a computation. The results of …

---

## [What is the real @time for an MPI program?](https://discourse.julialang.org/t/what-is-the-real-time-for-an-mpi-program/23458)

<div class="topic-metadata">

**Author:** [@Carol](https://discourse.julialang.org/u/Carol)\
**Replies:** 5\
**Last updated:** [May 10, 2019, 1:07am UTC](https://discourse.julialang.org/t/what-is-the-real-time-for-an-mpi-program/23458 "2019-05-10T01:07:44Z")

</div>

Hi, I have a question on timing an MPI code, because I want to test its performance. For example, if I split my code into 10 parallel jobs using MPI, then the @time will return 10 timing records. BTW, I also try to us…

---

## [Aliases for Union{T, Nothing} and Union{T, Missing}?](https://discourse.julialang.org/t/aliases-for-union-t-nothing-and-union-t-missing/15402)

<div class="topic-metadata">

**Author:** [@jandehaan](https://discourse.julialang.org/u/jandehaan)\
**Replies:** 40\
**Last updated:** [May 10, 2019, 12:10am UTC](https://discourse.julialang.org/t/aliases-for-union-t-nothing-and-union-t-missing/15402 "2019-05-10T00:10:42Z")

</div>

Does Julia (v1.0) define or is there a convention for aliases for Union{T, Nothing} and Union{T, Missing}? For example const Maybe{T} = Union{T,Nothing} const Option{T} = Union{T, Missing} I am aware of wrapper type S…

---

## [Julia 1.0.4 testing period](https://discourse.julialang.org/t/julia-1-0-4-testing-period/24051)

<div class="topic-metadata">

**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 0\
**Last updated:** [May 9, 2019, 10:30pm UTC](https://discourse.julialang.org/t/julia-1-0-4-testing-period/24051 "2019-05-09T22:30:56Z")

</div>

Hi again, you might remember me from my announcement of 1.1.1 testing just yesterday. Well, guess what: it’s that time again, except this time for 1.0. The release-1.0 branch on the Julia repository now contains the set…

---

## [Do you actually use FluxML to get work done?](https://discourse.julialang.org/t/do-you-actually-use-fluxml-to-get-work-done/23304)

<div class="topic-metadata">

**Author:** [@PhilipB](https://discourse.julialang.org/u/PhilipB)\
**Replies:** 16\
**Last updated:** [May 9, 2019, 9:21pm UTC](https://discourse.julialang.org/t/do-you-actually-use-fluxml-to-get-work-done/23304 "2019-05-09T21:21:08Z")

</div>

Hello. I am a student and I am studying tensor methods for deep learning. I decided to try Julia with FluxML yesterday, and so far I met 2 problems of type “FluxML tracked array doesn’t compile when used with this standa…

---

## [Parallelize simulations and print out results immediately when they are available](https://discourse.julialang.org/t/parallelize-simulations-and-print-out-results-immediately-when-they-are-available/24025)

<div class="topic-metadata">

**Author:** [@Xing\_Shi\_Cai](https://discourse.julialang.org/u/Xing_Shi_Cai)\
**Replies:** 4\
**Last updated:** [May 9, 2019, 8:59pm UTC](https://discourse.julialang.org/t/parallelize-simulations-and-print-out-results-immediately-when-they-are-available/24025 "2019-05-09T20:59:10Z")

</div>

I have currently some code like this function printsim(simulator, nsample) for i = 1:nsample println(simulation(simulator)) end end As soon as each simulation is over, I print it to standard output, wh…

---

## [Optimize not working with function that has find\_zero](https://discourse.julialang.org/t/optimize-not-working-with-function-that-has-find-zero/24043)

<div class="topic-metadata">

**Author:** [@jints07](https://discourse.julialang.org/u/jints07)\
**Replies:** 11\
**Last updated:** [May 9, 2019, 8:58pm UTC](https://discourse.julialang.org/t/optimize-not-working-with-function-that-has-find-zero/24043 "2019-05-09T20:58:36Z")

</div>

I have been using Julia on and off for over a year now. I know the basics but am not an expert by any means. I have had this problem many times in the past - some problem with forwardDiff not working because of floating …

---

## [Error with semi-colon, using a loop for writing to a file](https://discourse.julialang.org/t/error-with-semi-colon-using-a-loop-for-writing-to-a-file/24047)

<div class="topic-metadata">

**Author:** [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 8:45pm UTC](https://discourse.julialang.org/t/error-with-semi-colon-using-a-loop-for-writing-to-a-file/24047 "2019-05-09T20:45:17Z")

</div>

Julia is reporting a strange syntax error with semi-colon, when I am trying to use a loop for writing to a file. function print\_selected\_entries(select::Array{Int64,1}, v::Array{Float64,1}, file::String) N=size(select…

---

## [For loops acceleration](https://discourse.julialang.org/t/for-loops-acceleration/24011)

<div class="topic-metadata">

**Author:** [@Yifan\_Liu](https://discourse.julialang.org/u/Yifan_Liu)\
**Replies:** 9\
**Last updated:** [May 9, 2019, 8:41pm UTC](https://discourse.julialang.org/t/for-loops-acceleration/24011 "2019-05-09T20:41:44Z")

</div>

I have a function that involves several for loops that I would like to accelerate a little bit, but not sure if multi-threading is useful in my case. function SynDiv(option\_leverage = 5, Rf = 1, gamma = 0.1) W0 = 1…

---

## [Julia's in.() seems slow compared to R's %in%](https://discourse.julialang.org/t/julias-in-seems-slow-compared-to-rs-in/23900)

<div class="topic-metadata">

**Author:** [@alasaadstat](https://discourse.julialang.org/u/alasaadstat)\
**Replies:** 40\
**Last updated:** [May 9, 2019, 8:05pm UTC](https://discourse.julialang.org/t/julias-in-seems-slow-compared-to-rs-in/23900 "2019-05-09T20:05:36Z")

</div>

Hi everyone, I want to compare if elements of vector x are in elements of vector y. In R, I can do this as follows: \> x \<- c("a", "b", "c") \> y \<- c("b", "a") \> x %in% y \[1\] TRUE TRUE FALSE In Julia, I can do this a…

---

## [Fast Replotting](https://discourse.julialang.org/t/fast-replotting/24042)

<div class="topic-metadata">

**Author:** [@bjack205](https://discourse.julialang.org/u/bjack205)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 7:19pm UTC](https://discourse.julialang.org/t/fast-replotting/24042 "2019-05-09T19:19:35Z")

</div>

I can’t figure out the best way to continuously update a plot. I’ve dug around but haven’t found a good example of how to do this, yet. My use case is running simulations of dynamical systems, and I’d like to see how th…

---

## [Side Effects of println?](https://discourse.julialang.org/t/side-effects-of-println/24037)

<div class="topic-metadata">

**Author:** [@weech](https://discourse.julialang.org/u/weech)\
**Replies:** 7\
**Last updated:** [May 9, 2019, 5:58pm UTC](https://discourse.julialang.org/t/side-effects-of-println/24037 "2019-05-09T17:58:32Z")

</div>

I’m getting some really strange behavior, and I’m not sure what to make of it. Essentially the values in an array change based on making a call to println elsewhere in the script. I can’t figure out how to reproduce it i…

---

## [Global variables and program structure](https://discourse.julialang.org/t/global-variables-and-program-structure/6188)

<div class="topic-metadata">

**Author:** [@turtle](https://discourse.julialang.org/u/turtle)\
**Replies:** 15\
**Last updated:** [May 9, 2019, 5:53pm UTC](https://discourse.julialang.org/t/global-variables-and-program-structure/6188 "2019-05-09T17:53:09Z")

</div>

I am not proud of my program structure. My code is contained within a single module, my main variables are contained in 8 mutable composite types sometimes with as many as 30 type-annotated fields. Some of my functio…

---

## [Resizing Legend Markers in Plots with Matplotlib command](https://discourse.julialang.org/t/resizing-legend-markers-in-plots-with-matplotlib-command/24041)

<div class="topic-metadata">

**Author:** [@jman87](https://discourse.julialang.org/u/jman87)\
**Replies:** 0\
**Last updated:** [May 9, 2019, 5:25pm UTC](https://discourse.julialang.org/t/resizing-legend-markers-in-plots-with-matplotlib-command/24041 "2019-05-09T17:25:40Z")

</div>

I am using Julia 1.1.0 and plotting images using Plots with PyPlot backend. I need to find a way to make the size of markers in the legend be bigger. This issue has been asked before at least twice: I have found the …

---

## [Multiplying large numbers](https://discourse.julialang.org/t/multiplying-large-numbers/24032)

<div class="topic-metadata">

**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 4:46pm UTC](https://discourse.julialang.org/t/multiplying-large-numbers/24032 "2019-05-09T16:46:01Z")

</div>

---

## [OOM Killer on Linux](https://discourse.julialang.org/t/oom-killer-on-linux/22722)

<div class="topic-metadata">

**Author:** [@versipellis](https://discourse.julialang.org/u/versipellis)\
**Replies:** 5\
**Last updated:** [May 9, 2019, 3:57pm UTC](https://discourse.julialang.org/t/oom-killer-on-linux/22722 "2019-05-09T15:57:57Z")

</div>

I’m curious if anyone else has run into this. I’m on Ubuntu and trying to run an analysis on some really large datasets (40gigs binary, 1.5billion rows, 1600 chunks) using JuliaDB. I’ve frequently run into the issue whe…

---

## [Using Symbol within function (unexpected behaviour)](https://discourse.julialang.org/t/using-symbol-within-function-unexpected-behaviour/24029)

<div class="topic-metadata">

**Author:** [@dgs](https://discourse.julialang.org/u/dgs)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 3:39pm UTC](https://discourse.julialang.org/t/using-symbol-within-function-unexpected-behaviour/24029 "2019-05-09T15:39:37Z")

</div>

Hello, I am currently running some simulations and would like to serialize some parameters for the model. Using symbols I thought I could get away with a concise way of writing it : c, d = 1, 2 …

---

## [Matrix Multiplication A\*B\*A'](https://discourse.julialang.org/t/matrix-multiplication-a-b-a/24019)

<div class="topic-metadata">

**Author:** [@Marco-Congedo](https://discourse.julialang.org/u/Marco-Congedo)\
**Replies:** 5\
**Last updated:** [May 9, 2019, 3:39pm UTC](https://discourse.julialang.org/t/matrix-multiplication-a-b-a/24019 "2019-05-09T15:39:00Z")

</div>

What are the efficient options to perform matrix multiplications of the form A\*B\*A and A\*B\*A' ? I am particularly intereted in the case when A and B are Symmetric or Hermitian and when these multiplications are performed…

---

## [Inconsistent rebinding rules for function arguments](https://discourse.julialang.org/t/inconsistent-rebinding-rules-for-function-arguments/23990)

<div class="topic-metadata">

**Author:** [@HFriberg-mosek](https://discourse.julialang.org/u/HFriberg-mosek)\
**Replies:** 16\
**Last updated:** [May 9, 2019, 2:32pm UTC](https://discourse.julialang.org/t/inconsistent-rebinding-rules-for-function-arguments/23990 "2019-05-09T14:32:43Z")

</div>

The function below is a minimal example of a bug I have seen a couple of times: function update!(x) dx = \[1\] # Compute change x += dx # Update x (developer intended to write x .+= dx) # Any tests here show…

---

## [Bayesian Neural Network (Multiclass Classification) in Turing.jl and Flux.jl](https://discourse.julialang.org/t/bayesian-neural-network-multiclass-classification-in-turing-jl-and-flux-jl/21134)

<div class="topic-metadata">

**Author:** [@alasaadstat](https://discourse.julialang.org/u/alasaadstat)\
**Replies:** 5\
**Last updated:** [May 9, 2019, 3:08pm UTC](https://discourse.julialang.org/t/bayesian-neural-network-multiclass-classification-in-turing-jl-and-flux-jl/21134 "2019-05-09T15:08:01Z")

</div>

I want to do a multiclass classification using Bayesian Neural Network (BNN) in Turing.jl and Flux.jl. There’s a good implementation already of the binary classification using BNN in Turing.jl, check it here. Hence, my g…

---

## [Segfault building a system image for pyjulia with Anaconda Python (mac)](https://discourse.julialang.org/t/segfault-building-a-system-image-for-pyjulia-with-anaconda-python-mac/24033)

<div class="topic-metadata">

**Author:** [@evanfields](https://discourse.julialang.org/u/evanfields)\
**Replies:** 0\
**Last updated:** [May 9, 2019, 2:49pm UTC](https://discourse.julialang.org/t/segfault-building-a-system-image-for-pyjulia-with-anaconda-python-mac/24033 "2019-05-09T14:49:45Z")

</div>

My company uses Anaconda python, so I’m trying to use pyjulia. I tried building a system image following the instructions in the docs, and ran into a segfault: (pyjulia) evans-mbp:pyjl\_test evan$ which python3 /Users/ev…

---

## [How hard would it be to implement Numpy.jl, i.e. Numpy in Julia?](https://discourse.julialang.org/t/how-hard-would-it-be-to-implement-numpy-jl-i-e-numpy-in-julia/22080)

<div class="topic-metadata">

**Author:** [@Pierre\_Augier](https://discourse.julialang.org/u/Pierre_Augier)\
**Replies:** 71\
**Last updated:** [May 9, 2019, 2:24pm UTC](https://discourse.julialang.org/t/how-hard-would-it-be-to-implement-numpy-jl-i-e-numpy-in-julia/22080 "2019-05-09T14:24:12Z")

</div>

Hi, I’m working with Pythran (http://github.com/serge-sans-paille/pythran), a Python/Numpy to C++ transpiler, which of course supports only a subset of Python (in particular not all the crazy cool Python stuffs stupid f…

---

## [File organization and naming for tests](https://discourse.julialang.org/t/file-organization-and-naming-for-tests/24028)

<div class="topic-metadata">

**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 1\
**Last updated:** [May 9, 2019, 12:59pm UTC](https://discourse.julialang.org/t/file-organization-and-naming-for-tests/24028 "2019-05-09T12:59:48Z")

</div>

I am looking for a way of organizing test/ directories for large projects, mainly because if I settled on a way then I would not have to think about it :wink: (I found this topic which is loosely related.) To make thing…

---

## [Julia 1.1.1 testing period](https://discourse.julialang.org/t/julia-1-1-1-testing-period/24010)

<div class="topic-metadata">

**Author:** [@ararslan](https://discourse.julialang.org/u/ararslan)\
**Replies:** 3\
**Last updated:** [May 9, 2019, 12:05pm UTC](https://discourse.julialang.org/t/julia-1-1-1-testing-period/24010 "2019-05-09T12:05:48Z")

</div>

The release-1.1 branch on the Julia repository now contains the set of commits we’re planning to tag as v1.1.1, the first patch release in the 1.1 series. The list of commits included since v1.1.0 is available here. As a…

---

## [Small world index computation](https://discourse.julialang.org/t/small-world-index-computation/24024)

<div class="topic-metadata">

**Author:** [@pegger0709](https://discourse.julialang.org/u/pegger0709)\
**Replies:** 0\
**Last updated:** [May 9, 2019, 11:57am UTC](https://discourse.julialang.org/t/small-world-index-computation/24024 "2019-05-09T11:57:03Z")

</div>

Hello, I was just wondering whether LightGraphs has a function to compute the small-world index of a graph (like networkx does, but hopefully faster…) Thanks, Philip

---

## [For loop giving "no method matching iterate" error](https://discourse.julialang.org/t/for-loop-giving-no-method-matching-iterate-error/24021)

<div class="topic-metadata">

**Author:** [@Freestyler](https://discourse.julialang.org/u/Freestyler)\
**Replies:** 1\
**Last updated:** [May 9, 2019, 11:44am UTC](https://discourse.julialang.org/t/for-loop-giving-no-method-matching-iterate-error/24021 "2019-05-09T11:44:26Z")

</div>

Hi, I have some scripts that I would like to debug (using Atom + Juno). If my understanding of the Julia debugger mechanics is correct, I have to wrap the code in a function in order to be able to call it, so I wrapped…

---

## [How to construct a MetaGraph from a weighted adjacency matrix](https://discourse.julialang.org/t/how-to-construct-a-metagraph-from-a-weighted-adjacency-matrix/23996)

<div class="topic-metadata">

**Author:** [@pegger0709](https://discourse.julialang.org/u/pegger0709)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 11:41am UTC](https://discourse.julialang.org/t/how-to-construct-a-metagraph-from-a-weighted-adjacency-matrix/23996 "2019-05-09T11:41:58Z")

</div>

Hello, I am a researcher studying structural brain networks of stroke patients. I have some connectomes which are given as symmetric weighted matrices, e.g. (as a random example) julia\> X = rand(300,300); C = Symmetric…

---

## [Fail to install PyCall](https://discourse.julialang.org/t/fail-to-install-pycall/24016)

<div class="topic-metadata">

**Author:** [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)\
**Replies:** 2\
**Last updated:** [May 9, 2019, 11:37am UTC](https://discourse.julialang.org/t/fail-to-install-pycall/24016 "2019-05-09T11:37:50Z")

</div>

Hi, In Julia 1.1.0, Windows, I try to build PyCall (with a view to PyPlot). Julia\> Pkg.build(“PyCall”) Building Conda ─→ C:\\Users\\philippem\\.julia\\packages\\Conda\\CpuvI\\deps\\build.log Building PyCall → C:\\Users\\phili…

---

## [Why does exporting a single Float64 from a function take as long as 2,000,000 addition steps](https://discourse.julialang.org/t/why-does-exporting-a-single-float64-from-a-function-take-as-long-as-2-000-000-addition-steps/24008)

<div class="topic-metadata">

**Author:** [@damonturney](https://discourse.julialang.org/u/damonturney)\
**Replies:** 21\
**Last updated:** [May 9, 2019, 9:04am UTC](https://discourse.julialang.org/t/why-does-exporting-a-single-float64-from-a-function-take-as-long-as-2-000-000-addition-steps/24008 "2019-05-09T09:04:15Z")

</div>

Hi Forum, Can someone enlighten me as to why a single Float64 export from inside a function takes as much computation time as 2,000,000 additions? See code below from Julia 1.1. module test struct teststruct …

[Previous page](https://discourse.julialang.org/latest.md?page=1997)

[Next page](https://discourse.julialang.org/latest.md?page=1999)