# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1606

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

**Page:** 1607

---

## [Is there an equivalent to dplyr::across](https://discourse.julialang.org/t/is-there-an-equivalent-to-dplyr-across/48129)

<div class="topic-metadata">

**Author:** [@Derek\_Vetsch](https://discourse.julialang.org/u/Derek_Vetsch)\
**Replies:** 2\
**Last updated:** [October 11, 2020, 12:04am UTC](https://discourse.julialang.org/t/is-there-an-equivalent-to-dplyr-across/48129 "2020-10-11T00:04:59Z")

</div>

So I am trying to switch my employer’s credit modeling code base over to Julia but am running into issues with wide datasets. In R you can apply a function to multiple columns columnwise, for example using dplyr to squar…

---

## [Geometry calculations with STL file?](https://discourse.julialang.org/t/geometry-calculations-with-stl-file/48126)

<div class="topic-metadata">

**Author:** [@dlakelan](https://discourse.julialang.org/u/dlakelan)\
**Replies:** 5\
**Last updated:** [October 10, 2020, 10:24pm UTC](https://discourse.julialang.org/t/geometry-calculations-with-stl-file/48126 "2020-10-10T22:24:42Z")

</div>

I have a friend who wants to calculate some things based on geometry described by STL files (basically he’s got an OpenSCAD model, and he wants to do things like calculate the volumes of different things, and then based …

---

## [HTTP: How save a Cookie](https://discourse.julialang.org/t/http-how-save-a-cookie/48122)

<div class="topic-metadata">

**Author:** [@Jea](https://discourse.julialang.org/u/Jea)\
**Replies:** 0\
**Last updated:** [October 10, 2020, 7:34pm UTC](https://discourse.julialang.org/t/http-how-save-a-cookie/48122 "2020-10-10T19:34:12Z")

</div>

How can I save a cookie with HTTP.jl (https://github.com/JuliaWeb/HTTP.jl) in a persistent way, with its due expiration date

---

## [Creating a specialisation of a built-in type?](https://discourse.julialang.org/t/creating-a-specialisation-of-a-built-in-type/48119)

<div class="topic-metadata">

**Author:** [@foobar](https://discourse.julialang.org/u/foobar)\
**Replies:** 1\
**Last updated:** [October 10, 2020, 5:51pm UTC](https://discourse.julialang.org/t/creating-a-specialisation-of-a-built-in-type/48119 "2020-10-10T17:51:25Z")

</div>

Hi, I want to work through the “Ray Tracer Challenge” book whilst learning julia. To do so I’d like to achieve the following: have a MyTuple type that acts exactly as regular tuples do be able to redefine operators f…

---

## [ANN: Reverse Cuthill-McKee sparse matrix renumbering](https://discourse.julialang.org/t/ann-reverse-cuthill-mckee-sparse-matrix-renumbering/44427)

<div class="topic-metadata">

**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 3\
**Last updated:** [October 10, 2020, 5:43pm UTC](https://discourse.julialang.org/t/ann-reverse-cuthill-mckee-sparse-matrix-renumbering/44427 "2020-10-10T17:43:19Z")

</div>

In the process of being registered: https://github.com/JuliaRegistries/General/pull/19106

---

## [Sharing Template for Julia on Colab with Google Drive Mounted](https://discourse.julialang.org/t/sharing-template-for-julia-on-colab-with-google-drive-mounted/47991)

<div class="topic-metadata">

**Author:** [@pxshen](https://discourse.julialang.org/u/pxshen)\
**Replies:** 0\
**Last updated:** [October 8, 2020, 3:46pm UTC](https://discourse.julialang.org/t/sharing-template-for-julia-on-colab-with-google-drive-mounted/47991 "2020-10-08T15:46:22Z")

</div>

Hey I’m sharing my template for running Julia on Colab with Google Drive Mounted. Thanks :slight\_smile:

---

## [Sr Research Engineer at Metalenz \[Boston, MA\]](https://discourse.julialang.org/t/sr-research-engineer-at-metalenz-boston-ma/39367)

<div class="topic-metadata">

**Author:** [@platawiec](https://discourse.julialang.org/u/platawiec)\
**Replies:** 0\
**Last updated:** [May 12, 2020, 8:06pm UTC](https://discourse.julialang.org/t/sr-research-engineer-at-metalenz-boston-ma/39367 "2020-05-12T20:06:51Z")

</div>

Metalenz is a growing, venture-backed start-up commercializing metasurface optical systems. Metalenz is seeking a Sr Research Engineer to contribute to the functionality and architecture of a Julia codebase which enable…

---

## [We are live all day on Gather Town for Hacktoberfest 2020!](https://discourse.julialang.org/t/we-are-live-all-day-on-gather-town-for-hacktoberfest-2020/48113)

<div class="topic-metadata">

**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 0\
**Last updated:** [October 10, 2020, 3:09pm UTC](https://discourse.julialang.org/t/we-are-live-all-day-on-gather-town-for-hacktoberfest-2020/48113 "2020-10-10T15:09:18Z")

</div>

Hey all! We are live for our Hacktoberfest Meetup all day on: Gather Feel free to join to do some hacking and say hi to members of the community!

---

## [Error in mul!(c,a,b) if size(b) = (n,1)](https://discourse.julialang.org/t/error-in-mul-c-a-b-if-size-b-n-1/47999)

<div class="topic-metadata">

**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 28\
**Last updated:** [October 10, 2020, 2:50pm UTC](https://discourse.julialang.org/t/error-in-mul-c-a-b-if-size-b-n-1/47999 "2020-10-10T14:50:09Z")

</div>

Just to put in context. If I read using DelimitedFiles the data from a file with a single column of data, with, for example, x = readdlm("./data.txt") x is returned as an Array{Float64,2} with sizes (n,1). If I try dir…

---

## [Pairwise Alignment Score function: From Python to Julia. Suggestions](https://discourse.julialang.org/t/pairwise-alignment-score-function-from-python-to-julia-suggestions/48089)

<div class="topic-metadata">

**Author:** [@aadam](https://discourse.julialang.org/u/aadam)\
**Replies:** 3\
**Last updated:** [October 10, 2020, 1:23pm UTC](https://discourse.julialang.org/t/pairwise-alignment-score-function-from-python-to-julia-suggestions/48089 "2020-10-10T13:23:24Z")

</div>

I wanted a function to compute the Pairwise Alignment Score in Julia, but didn’t find any in the BioJulia repository. I submitted an issue, asking for some guidance, but no response till now. So, after waiting a long tim…

---

## [Not sure why my CI is failing for a Particular Version?](https://discourse.julialang.org/t/not-sure-why-my-ci-is-failing-for-a-particular-version/48106)

<div class="topic-metadata">

**Author:** [@DataPsycho](https://discourse.julialang.org/u/DataPsycho)\
**Replies:** 2\
**Last updated:** [October 10, 2020, 1:18pm UTC](https://discourse.julialang.org/t/not-sure-why-my-ci-is-failing-for-a-particular-version/48106 "2020-10-10T13:18:39Z")

</div>

Hi, My local machine has julia version 1.5. My CI is failing for version 1.1. Not sure what is the problem, I tells about some unsatisfied dependencies. Can some one can tell what is the problem. Here is the CI pipeline…

---

## [Does Optim not support function optimization with matrix variables?](https://discourse.julialang.org/t/does-optim-not-support-function-optimization-with-matrix-variables/47475)

<div class="topic-metadata">

**Author:** [@F-YF](https://discourse.julialang.org/u/F-YF)\
**Replies:** 14\
**Last updated:** [October 10, 2020, 11:49am UTC](https://discourse.julialang.org/t/does-optim-not-support-function-optimization-with-matrix-variables/47475 "2020-10-10T11:49:16Z")

</div>

I want to optimize my function with Optim, but something went wrong . I have written an example. Does this example show that optim.jl does not support functions whose variables are matrices?If not, what should I do about…

---

## [Mean of each column in a DataFrame?](https://discourse.julialang.org/t/mean-of-each-column-in-a-dataframe/48105)

<div class="topic-metadata">

**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 4\
**Last updated:** [October 10, 2020, 11:45am UTC](https://discourse.julialang.org/t/mean-of-each-column-in-a-dataframe/48105 "2020-10-10T11:45:40Z")

</div>

Hi! What would be the cleanest way to find the mean of each column in a dataframe? I would like to avoid writing for loops, since I think it should be possible without it. Kind regards

---

## [Which package/function for signed distance fields?](https://discourse.julialang.org/t/which-package-function-for-signed-distance-fields/43487)

<div class="topic-metadata">

**Author:** [@weymouth](https://discourse.julialang.org/u/weymouth)\
**Replies:** 3\
**Last updated:** [October 10, 2020, 9:44am UTC](https://discourse.julialang.org/t/which-package-function-for-signed-distance-fields/43487 "2020-10-10T09:44:02Z")

</div>

I need a signed distance field (SDF) and corresponding unit normal vector field (acronym unknown) to immerse solid boundaries into my fluid simulator. I’m trying to use “other people’s code” wherever possible on this pro…

---

## [Reason for the time difference in assigning columns with dot syntax](https://discourse.julialang.org/t/reason-for-the-time-difference-in-assigning-columns-with-dot-syntax/48030)

<div class="topic-metadata">

**Author:** [@Shuhua](https://discourse.julialang.org/u/Shuhua)\
**Replies:** 10\
**Last updated:** [October 10, 2020, 8:49am UTC](https://discourse.julialang.org/t/reason-for-the-time-difference-in-assigning-columns-with-dot-syntax/48030 "2020-10-10T08:49:33Z")

</div>

julia\> const N = 10000; julia\> const x = rand(N); julia\> const m = zeros(N, 2); julia\> using BenchmarkTools julia\> @btime $m\[:, 1\] = $x; 12.799 μs (0 allocations: 0 bytes) julia\> @btime $m\[:, 1\] .= $x; 2.633 μs …

---

## [Failed process](https://discourse.julialang.org/t/failed-process/48012)

<div class="topic-metadata">

**Author:** [@Leslie\_Aylin\_Chavez](https://discourse.julialang.org/u/Leslie_Aylin_Chavez)\
**Replies:** 6\
**Last updated:** [October 10, 2020, 7:46am UTC](https://discourse.julialang.org/t/failed-process/48012 "2020-10-10T07:46:13Z")

</div>

Hola, soy nueva en Julia e intento descargar Jupyter notebooks sin embargo cuando pongo notebook en la consola me aparece la opción que si quiero descargarlo en conda, escribo que si pero al final me aparece un failed pr…

---

## [Julia on cluster, only MPI transport allowed](https://discourse.julialang.org/t/julia-on-cluster-only-mpi-transport-allowed/47958)

<div class="topic-metadata">

**Author:** [@sparrowhawk](https://discourse.julialang.org/u/sparrowhawk)\
**Replies:** 7\
**Last updated:** [October 10, 2020, 7:44am UTC](https://discourse.julialang.org/t/julia-on-cluster-only-mpi-transport-allowed/47958 "2020-10-10T07:44:16Z")

</div>

Hi all, I’m on a PBS cluster where I cannot simply provide a machine file to julia. After a lot of trials, I found that only MPI transport works on the cluster, and I was able to adapt an MPIClusterManagers.jl example w…

---

## ["ERROR: LoadError: LoadError: UndefVarError: AbstractADType not defined" during GalacticOpim precompilation](https://discourse.julialang.org/t/error-loaderror-loaderror-undefvarerror-abstractadtype-not-defined-during-galacticopim-precompilation/48008)

<div class="topic-metadata">

**Author:** [@checco.jike](https://discourse.julialang.org/u/checco.jike)\
**Replies:** 8\
**Last updated:** [October 10, 2020, 5:56am UTC](https://discourse.julialang.org/t/error-loaderror-loaderror-undefvarerror-abstractadtype-not-defined-during-galacticopim-precompilation/48008 "2020-10-10T05:56:23Z")

</div>

I tried using this example found here: https://github.com/SciML/NeuralPDE.jl but I get the error “ERROR: LoadError: LoadError: UndefVarError: AbstractADType not defined” during the precompilation of the GalacticOptim pac…

---

## [Monads and monoids in julia](https://discourse.julialang.org/t/monads-and-monoids-in-julia/47745)

<div class="topic-metadata">

**Author:** [@bicepjai](https://discourse.julialang.org/u/bicepjai)\
**Replies:** 12\
**Last updated:** [October 10, 2020, 5:03am UTC](https://discourse.julialang.org/t/monads-and-monoids-in-julia/47745 "2020-10-10T05:03:43Z")

</div>

I am trying to get a grip on how to think in terms of functional programming concepts thru Scott Wlaschin’s videos and implement them in julia The Functional Toolkit - Scott Wlaschin - YouTube Functional programming de…

---

## [\[ANN\] ConcreteStructs.jl - Cut the boilerplate when concretely parameterizing structs](https://discourse.julialang.org/t/ann-concretestructs-jl-cut-the-boilerplate-when-concretely-parameterizing-structs/47274)

<div class="topic-metadata">

**Author:** [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Replies:** 13\
**Last updated:** [October 10, 2020, 4:19am UTC](https://discourse.julialang.org/t/ann-concretestructs-jl-cut-the-boilerplate-when-concretely-parameterizing-structs/47274 "2020-10-10T04:19:31Z")

</div>

The Problem Defining concretely parameterized structs involves quite a bit of boilerplate code. Consider the following definition from DifferentialEquations.jl: struct ODEFunction{iip,F,TMM,Ta,Tt,TJ,JVP,VJP,JP,SP,TW,TWt…

---

## [Change Array in Interpolation without recreating weights](https://discourse.julialang.org/t/change-array-in-interpolation-without-recreating-weights/48077)

<div class="topic-metadata">

**Author:** [@Sam\_Collie](https://discourse.julialang.org/u/Sam_Collie)\
**Replies:** 1\
**Last updated:** [October 10, 2020, 3:57am UTC](https://discourse.julialang.org/t/change-array-in-interpolation-without-recreating-weights/48077 "2020-10-10T03:57:19Z")

</div>

I’d like to change the Array of data within an interpolation without recreating a new instance of the interpolant. Here is a MWE: I am using the same nodes in each instance, so it seems there should be a performance gai…

---

## [Manual link does not work](https://discourse.julialang.org/t/manual-link-does-not-work/48083)

<div class="topic-metadata">

**Author:** [@vaeli](https://discourse.julialang.org/u/vaeli)\
**Replies:** 0\
**Last updated:** [October 10, 2020, 1:28am UTC](https://discourse.julialang.org/t/manual-link-does-not-work/48083 "2020-10-10T01:28:33Z")

</div>

http://juliagraphics.github.io/Gtk.jl/v0.17/doc/precompilation.md - building into local installation of Gtk does not work

---

## [How to simulate a random signal sequence change](https://discourse.julialang.org/t/how-to-simulate-a-random-signal-sequence-change/47964)

<div class="topic-metadata">

**Author:** [@aachener](https://discourse.julialang.org/u/aachener)\
**Replies:** 4\
**Last updated:** [October 10, 2020, 3:22am UTC](https://discourse.julialang.org/t/how-to-simulate-a-random-signal-sequence-change/47964 "2020-10-10T03:22:10Z")

</div>

I have got a simple problem to calculate Posterior after some signal disturbances. Say the input signal is a sequence of 0 and 1 with 70% of chance is 1. And somehow we know that after the transmission, the output have …

---

## [Base.similar (and Zygote.Buffer) returning undefined instead of array of arrays](https://discourse.julialang.org/t/base-similar-and-zygote-buffer-returning-undefined-instead-of-array-of-arrays/48078)

<div class="topic-metadata">

**Author:** [@vaglino](https://discourse.julialang.org/u/vaglino)\
**Replies:** 1\
**Last updated:** [October 10, 2020, 3:04am UTC](https://discourse.julialang.org/t/base-similar-and-zygote-buffer-returning-undefined-instead-of-array-of-arrays/48078 "2020-10-10T03:04:12Z")

</div>

I am trying to initialize an array of arrays using similar and Zygote.buffer. If I initialize an array the functions work as expected, i.e. a = \[0., 0.\] similar(a) 2-element Array{Float64,1}: 7.229478454414514e221 2…

---

## [How to initialize an array of AbstractArray？](https://discourse.julialang.org/t/how-to-initialize-an-array-of-abstractarray/48022)

<div class="topic-metadata">

**Author:** [@F-YF](https://discourse.julialang.org/u/F-YF)\
**Replies:** 8\
**Last updated:** [October 10, 2020, 2:39am UTC](https://discourse.julialang.org/t/how-to-initialize-an-array-of-abstractarray/48022 "2020-10-10T02:39:42Z")

</div>

How do I initialize a one-dimensional array, where each element of the array is a two-dimensional array? For example, I need to initialize a one-dimensional array of length three :\[\[0 0, 0 0\], \[0 0 0, 0 0 0\], \[0 0 0, 0 …

---

## [Overloaded function](https://discourse.julialang.org/t/overloaded-function/48085)

<div class="topic-metadata">

**Author:** [@F-YF](https://discourse.julialang.org/u/F-YF)\
**Replies:** 2\
**Last updated:** [October 10, 2020, 2:38am UTC](https://discourse.julialang.org/t/overloaded-function/48085 "2020-10-10T02:38:17Z")

</div>

How to overload a function in Base function. For instance, how should I do the following: function abs(A::Array{Int64,2}) return abs.(A) end Error message: error in method definition: function Base.abs must be e…

---

## [Unique doesn't seem to obey == definitions](https://discourse.julialang.org/t/unique-doesnt-seem-to-obey-definitions/47455)

<div class="topic-metadata">

**Author:** [@pengwyn](https://discourse.julialang.org/u/pengwyn)\
**Replies:** 7\
**Last updated:** [October 10, 2020, 2:07am UTC](https://discourse.julialang.org/t/unique-doesnt-seem-to-obey-definitions/47455 "2020-10-10T02:07:22Z")

</div>

The behaviour for unique(itr) doesn’t seem to follow the documentation which specifies items are compared using an isequal check. This got me when I have a custom struct, e.g. mutable struct A x end Base.var"=="(one::A…

---

## [Easiest way to do Contour & 3D Plots of Semi-Discrete solution data?](https://discourse.julialang.org/t/easiest-way-to-do-contour-3d-plots-of-semi-discrete-solution-data/47115)

<div class="topic-metadata">

**Author:** [@CosmoProf](https://discourse.julialang.org/u/CosmoProf)\
**Replies:** 6\
**Last updated:** [October 9, 2020, 11:45pm UTC](https://discourse.julialang.org/t/easiest-way-to-do-contour-3d-plots-of-semi-discrete-solution-data/47115 "2020-10-09T23:45:23Z")

</div>

Hi, I have a method-of-lines solution to a 2nd-order PDE, where the solution “sol” is discrete in x, has columns for discrete data points df/dt and f, and has an ODE-type solution which can be either discrete or continuo…

---

## [Enable logging after disabling logging](https://discourse.julialang.org/t/enable-logging-after-disabling-logging/48073)

<div class="topic-metadata">

**Author:** [@ranjan](https://discourse.julialang.org/u/ranjan)\
**Replies:** 0\
**Last updated:** [October 9, 2020, 10:55pm UTC](https://discourse.julialang.org/t/enable-logging-after-disabling-logging/48073 "2020-10-09T22:55:43Z")

</div>

I’m trying to enable global logging after disabling it. Is this the right/recommended way to do it? julia\> module A using Logging f() = @info("hi") end Main.A julia\> A.f() \[ Info: hi julia\>…

---

## [Use constant variable from outer module in inner module](https://discourse.julialang.org/t/use-constant-variable-from-outer-module-in-inner-module/48032)

<div class="topic-metadata">

**Author:** [@Impressium](https://discourse.julialang.org/u/Impressium)\
**Replies:** 3\
**Last updated:** [October 9, 2020, 10:54pm UTC](https://discourse.julialang.org/t/use-constant-variable-from-outer-module-in-inner-module/48032 "2020-10-09T22:54:59Z")

</div>

Hey community :slight\_smile: I’ve got a question about modules. I want to use a field of an outer module in an inner module. How would I do that? module A const A\_const = "stuff" module B do\_stuff(A\_const) …

[Previous page](https://discourse.julialang.org/latest.md?page=1605)

[Next page](https://discourse.julialang.org/latest.md?page=1607)