# General Usage

**URL:** https://discourse.julialang.org/c/usage/6.md?page=611

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

**Page:** 612

---

## [How to know the time between lines, not for a specific function](https://discourse.julialang.org/t/how-to-know-the-time-between-lines-not-for-a-specific-function/59558)

<div class="topic-metadata">

**Author:** [@AlphaF20](https://discourse.julialang.org/u/AlphaF20)\
**Replies:** 2\
**Last updated:** [April 18, 2021, 6:22pm UTC](https://discourse.julialang.org/t/how-to-know-the-time-between-lines-not-for-a-specific-function/59558 "2021-04-18T18:22:42Z")

</div>

From Performance Tips · The Julia Language it seems to me that @time is for a specific function Is there any method to know the time for a few lines have been executed? E.g., in python, one may write start\_time = tim…

---

## [Understanding the performance issue in combine() \[DataFrames.jl\]](https://discourse.julialang.org/t/understanding-the-performance-issue-in-combine-dataframes-jl/59531)

<div class="topic-metadata">

**Author:** [@DataFrames](https://discourse.julialang.org/u/DataFrames)\
**Replies:** 1\
**Last updated:** [April 18, 2021, 12:53pm UTC](https://discourse.julialang.org/t/understanding-the-performance-issue-in-combine-dataframes-jl/59531 "2021-04-18T12:53:00Z")

</div>

I have the following performance issue with user defined function in combine(). Assume df = DataFrame(g = rand(1:100,1000), x = rand(1000)) and temp\_fun(x) = sum(x) the performance of combine() in the following two s…

---

## [Embedding julia 1.6.0](https://discourse.julialang.org/t/embedding-julia-1-6-0/58898)

<div class="topic-metadata">

**Author:** [@maarten\_van\_damme](https://discourse.julialang.org/u/maarten_van_damme)\
**Replies:** 2\
**Last updated:** [April 18, 2021, 11:06am UTC](https://discourse.julialang.org/t/embedding-julia-1-6-0/58898 "2021-04-18T11:06:41Z")

</div>

I’m trying to solve https://github.com/jebej/Mex.jl/issues/6 . To embed julia in matlab, it appears you need to turn of signal handling. In 1.6, some things got separated out into libjulia-internal, of which I can find n…

---

## [Trying to understand reported error](https://discourse.julialang.org/t/trying-to-understand-reported-error/59523)

<div class="topic-metadata">

**Author:** [@quazirfan](https://discourse.julialang.org/u/quazirfan)\
**Replies:** 3\
**Last updated:** [April 18, 2021, 9:25am UTC](https://discourse.julialang.org/t/trying-to-understand-reported-error/59523 "2021-04-18T09:25:36Z")

</div>

I am trying to solve Temperature Variation problem on Project Lovelace. The problem is given a list of numbers, find the mean and standard deviation. I have written the following code, function temperature\_statistics(T…

---

## [Question about Multiple prediction](https://discourse.julialang.org/t/question-about-multiple-prediction/59527)

<div class="topic-metadata">

**Author:** [@abcde](https://discourse.julialang.org/u/abcde)\
**Replies:** 0\
**Last updated:** [April 18, 2021, 8:18am UTC](https://discourse.julialang.org/t/question-about-multiple-prediction/59527 "2021-04-18T08:18:14Z")

</div>

I am working on the forecasting of power system operation mode.This is a prediction problem with multiple input and multiple output variables coupled to each other,Is there a recommended algorithm or Pkg? thank you !!!

---

## [Activating a separate environment](https://discourse.julialang.org/t/activating-a-separate-environment/59515)

<div class="topic-metadata">

**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 2\
**Last updated:** [April 18, 2021, 8:15am UTC](https://discourse.julialang.org/t/activating-a-separate-environment/59515 "2021-04-18T08:15:12Z")

</div>

how to activate a separate environment for julia 1.6.0 from julia 1.5.4? (@v1.6) pkg\> activate env1.6 Activating new environment at \`C:\\Users\\hermesr\\env1.6\\Project.toml\` (env1.6) pkg\> add Plots Updating registry…

---

## [Is it possble for Julia to overwrite how to get field](https://discourse.julialang.org/t/is-it-possble-for-julia-to-overwrite-how-to-get-field/59507)

<div class="topic-metadata">

**Author:** [@oyczyco13](https://discourse.julialang.org/u/oyczyco13)\
**Replies:** 6\
**Last updated:** [April 18, 2021, 2:40am UTC](https://discourse.julialang.org/t/is-it-possble-for-julia-to-overwrite-how-to-get-field/59507 "2021-04-18T02:40:57Z")

</div>

struct A obj::B field1 field2 field3 end struct B field4 field5 end b = B(4, 5) a = A(b, 1, 2 ,3) a.field4 I expect a is able to get field4 from a.b (if there is one) by calling a.field4, just…

---

## [Missing module documentation under Requires.jl](https://discourse.julialang.org/t/missing-module-documentation-under-requires-jl/58454)

<div class="topic-metadata">

**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 1\
**Last updated:** [April 18, 2021, 12:28am UTC](https://discourse.julialang.org/t/missing-module-documentation-under-requires-jl/58454 "2021-04-18T00:28:25Z")

</div>

Hello, I am developing a data processing package. This package contains plotting functionalities from PyPlot.jl, but I don’t want to include that as an explicit dependency, so I choose to use Requires.jl to accomplish t…

---

## [Trying to understand jll dependency version](https://discourse.julialang.org/t/trying-to-understand-jll-dependency-version/59504)

<div class="topic-metadata">

**Author:** [@Egwene\_al\_Vere](https://discourse.julialang.org/u/Egwene_al_Vere)\
**Replies:** 1\
**Last updated:** [April 18, 2021, 12:11am UTC](https://discourse.julialang.org/t/trying-to-understand-jll-dependency-version/59504 "2021-04-18T00:11:12Z")

</div>

This comes up in my testing of the current nightly, v1.7, where using DifferentialEquations fails due to one of its dependencies (Sundials). This has been reported by someone here The gist might be: The current Sundi…

---

## [Trying to debug embedding of Julia in a JUCE (VST) audio plugin](https://discourse.julialang.org/t/trying-to-debug-embedding-of-julia-in-a-juce-vst-audio-plugin/58968)

<div class="topic-metadata">

**Author:** [@toivo](https://discourse.julialang.org/u/toivo)\
**Replies:** 2\
**Last updated:** [April 17, 2021, 5:45pm UTC](https://discourse.julialang.org/t/trying-to-debug-embedding-of-julia-in-a-juce-vst-audio-plugin/58968 "2021-04-17T17:45:10Z")

</div>

Hi! I’m trying to embed Julia into a VST plugin (using the JUCE framework) on windows. JUCE provides several build targets, and the standalone target works fine (after some tweaks related to embedding Julia on windows).…

---

## [Julia is Eight times Slower than Go on Numerical Scheme](https://discourse.julialang.org/t/julia-is-eight-times-slower-than-go-on-numerical-scheme/59383)

<div class="topic-metadata">

**Author:** [@ejolson](https://discourse.julialang.org/u/ejolson)\
**Replies:** 31\
**Last updated:** [April 17, 2021, 5:29pm UTC](https://discourse.julialang.org/t/julia-is-eight-times-slower-than-go-on-numerical-scheme/59383 "2021-04-17T17:29:47Z")

</div>

Here is a run of the Julia code conjulia -- Energy Conserving IRK Scheme y(0)=\[1.0, 1.0, 1.0\] p n h E(100) dE(100) error 7 128 7.8125000e-01 3.0000000e+00 0.00…

---

## [Why is big(0.5) printed as 0.50?](https://discourse.julialang.org/t/why-is-big-0-5-printed-as-0-50/59395)

<div class="topic-metadata">

**Author:** [@jishnub](https://discourse.julialang.org/u/jishnub)\
**Replies:** 6\
**Last updated:** [April 17, 2021, 5:06pm UTC](https://discourse.julialang.org/t/why-is-big-0-5-printed-as-0-50/59395 "2021-04-17T17:06:04Z")

</div>

I’m not sure if this is the intended behavior: julia\> 0.5 0.5 julia\> big(0.5) 0.50 julia\> big(0.5) == 0.5 true Why the extra 0 at the end for a BigFloat?

---

## [True power set of a set is slower than power array of array](https://discourse.julialang.org/t/true-power-set-of-a-set-is-slower-than-power-array-of-array/59464)

<div class="topic-metadata">

**Author:** [@Wei\_Yang](https://discourse.julialang.org/u/Wei_Yang)\
**Replies:** 3\
**Last updated:** [April 17, 2021, 4:34pm UTC](https://discourse.julialang.org/t/true-power-set-of-a-set-is-slower-than-power-array-of-array/59464 "2021-04-17T16:34:49Z")

</div>

I’m trying to create a power set function with only set operations, but it turns out to be much slower than the array version. I wonder why this is the case, and how to make the Set version as fast as the array version. …

---

## [Change directory before running an external command](https://discourse.julialang.org/t/change-directory-before-running-an-external-command/59479)

<div class="topic-metadata">

**Author:** [@curious](https://discourse.julialang.org/u/curious)\
**Replies:** 2\
**Last updated:** [April 17, 2021, 3:11pm UTC](https://discourse.julialang.org/t/change-directory-before-running-an-external-command/59479 "2021-04-17T15:11:52Z")

</div>

I have a julia file, say FileIwantToRun.jl in many folders/directories. I want to write a script that visits each of these directories and runs this file from those directories (it outputs a file that I want it to save i…

---

## [Orientation of 3d globe makie](https://discourse.julialang.org/t/orientation-of-3d-globe-makie/59478)

<div class="topic-metadata">

**Author:** [@gdkrmr](https://discourse.julialang.org/u/gdkrmr)\
**Replies:** 0\
**Last updated:** [April 17, 2021, 2:26pm UTC](https://discourse.julialang.org/t/orientation-of-3d-globe-makie/59478 "2021-04-17T14:26:22Z")

</div>

I am plotting a global data product on a 3d globe using Makie using with code below (sorry for not making this reproducible): m = uv\_normal\_mesh(GeometryBasics.Tesselation(Sphere(Point3f0(0), 6371000f0), 200)) scene = m…

---

## [Plots: where to find the list of available fonts? Is it possible to set all fonts simultaneously](https://discourse.julialang.org/t/plots-where-to-find-the-list-of-available-fonts-is-it-possible-to-set-all-fonts-simultaneously/59451)

<div class="topic-metadata">

**Author:** [@curious](https://discourse.julialang.org/u/curious)\
**Replies:** 6\
**Last updated:** [April 17, 2021, 2:00pm UTC](https://discourse.julialang.org/t/plots-where-to-find-the-list-of-available-fonts-is-it-possible-to-set-all-fonts-simultaneously/59451 "2021-04-17T14:00:08Z")

</div>

I am using Plots.jl to create some plots with the default backend (I think it is the gr backend). I know that I can set say the title font and the legend font to say “computer modern” using the command: Plots.default(ti…

---

## [Write access to a variable in a module](https://discourse.julialang.org/t/write-access-to-a-variable-in-a-module/59025)

<div class="topic-metadata">

**Author:** [@Eben60](https://discourse.julialang.org/u/Eben60)\
**Replies:** 6\
**Last updated:** [April 17, 2021, 11:32am UTC](https://discourse.julialang.org/t/write-access-to-a-variable-in-a-module/59025 "2021-04-17T11:32:11Z")

</div>

module Mdl b1 = false end import .Mdl.b1 julia\> b1 false julia\> b1=true ERROR: cannot assign a value to variable Mdl.b1 from module Main Stacktrace: \[1\] top-level scope @ none:1 Why? ( I know, I can use a setter…

---

## [Operation yields different results on other machine](https://discourse.julialang.org/t/operation-yields-different-results-on-other-machine/59442)

<div class="topic-metadata">

**Author:** [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Replies:** 3\
**Last updated:** [April 17, 2021, 4:31am UTC](https://discourse.julialang.org/t/operation-yields-different-results-on-other-machine/59442 "2021-04-17T04:31:48Z")

</div>

We’re running the same code on machine A and machine B (same Manifest file), and the results are not the same. We’re doing fairly straight-forward linear algebra on StaticArrays. Is that a bug, or is it generally accepte…

---

## [How to create a \`range\` centered around zero?](https://discourse.julialang.org/t/how-to-create-a-range-centered-around-zero/59344)

<div class="topic-metadata">

**Author:** [@Jorge\_Vieyra](https://discourse.julialang.org/u/Jorge_Vieyra)\
**Replies:** 26\
**Last updated:** [April 16, 2021, 11:27pm UTC](https://discourse.julialang.org/t/how-to-create-a-range-centered-around-zero/59344 "2021-04-16T23:27:24Z")

</div>

is there a way to make a range(-max, max, step=n) that is guaranteed to go through zero?, i.e. I want it to be symmetrical/centered around zero

---

## [Why use unevaluated expression to refer to a column name](https://discourse.julialang.org/t/why-use-unevaluated-expression-to-refer-to-a-column-name/59424)

<div class="topic-metadata">

**Author:** [@quazirfan](https://discourse.julialang.org/u/quazirfan)\
**Replies:** 8\
**Last updated:** [April 16, 2021, 8:00pm UTC](https://discourse.julialang.org/t/why-use-unevaluated-expression-to-refer-to-a-column-name/59424 "2021-04-16T20:00:34Z")

</div>

I understand that I need to use : operator to represent a variable in an unevaluated expression in Julia. But I am confused as to why I am using : to get column name here - the column name do not appear to be an unevalua…

---

## [Jupyter Lab LSP: argv path](https://discourse.julialang.org/t/jupyter-lab-lsp-argv-path/48115)

<div class="topic-metadata">

**Author:** [@fusion809](https://discourse.julialang.org/u/fusion809)\
**Replies:** 9\
**Last updated:** [April 16, 2021, 9:36pm UTC](https://discourse.julialang.org/t/jupyter-lab-lsp-argv-path/48115 "2021-04-16T21:36:17Z")

</div>

I’d like to be able to use Julia’s language server within Jupyter Lab. There’s an extension for Jupyter Lab that adds LSP integration. There’s a list of languages that are well-supported by the extension, unfortunately J…

---

## [Faster groupwise joins to complete implicitly missing rows](https://discourse.julialang.org/t/faster-groupwise-joins-to-complete-implicitly-missing-rows/59414)

<div class="topic-metadata">

**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 2\
**Last updated:** [April 16, 2021, 9:05pm UTC](https://discourse.julialang.org/t/faster-groupwise-joins-to-complete-implicitly-missing-rows/59414 "2021-04-16T21:05:53Z")

</div>

I have a grouped DataFrame with dates and values but only observe dates in which a value was observed. I’d like to create the rows that are implicitly missing and have them as missing e.g. for interpolation later. I came…

---

## [Covariance matrix estimation using HF data](https://discourse.julialang.org/t/covariance-matrix-estimation-using-hf-data/59440)

<div class="topic-metadata">

**Author:** [@Shahal](https://discourse.julialang.org/u/Shahal)\
**Replies:** 0\
**Last updated:** [April 16, 2021, 8:48pm UTC](https://discourse.julialang.org/t/covariance-matrix-estimation-using-hf-data/59440 "2021-04-16T20:48:42Z")

</div>

Hello, can anyone guide me where I can find Julia code for the estimation of cov matrix using the Hayashi Yoshida and Fourier methods?

---

## [Distributed Sampling with Turing with project environment](https://discourse.julialang.org/t/distributed-sampling-with-turing-with-project-environment/59368)

<div class="topic-metadata">

**Author:** [@bdeonovic](https://discourse.julialang.org/u/bdeonovic)\
**Replies:** 3\
**Last updated:** [April 16, 2021, 7:43pm UTC](https://discourse.julialang.org/t/distributed-sampling-with-turing-with-project-environment/59368 "2021-04-16T19:43:52Z")

</div>

I have some code in a project (that I setup with DrWatson.jl but I don’t think that is too important). I try to get Turing available on all procs with using Turing using Distributed addprocs(4) @everywhere using DrWa…

---

## [Transform() within missing column names](https://discourse.julialang.org/t/transform-within-missing-column-names/59434)

<div class="topic-metadata">

**Author:** [@mengxiaoliu](https://discourse.julialang.org/u/mengxiaoliu)\
**Replies:** 0\
**Last updated:** [April 16, 2021, 7:38pm UTC](https://discourse.julialang.org/t/transform-within-missing-column-names/59434 "2021-04-16T19:38:59Z")

</div>

I am using the transform() function on a simple dataframe to achieve two purposes: I want to create the same number of columns (with the same names) as rows. I want to create a column named “Total” which adds up the nu…

---

## [Apply transform() to all DataFrame columns of a certain type?](https://discourse.julialang.org/t/apply-transform-to-all-dataframe-columns-of-a-certain-type/59433)

<div class="topic-metadata">

**Author:** [@florian](https://discourse.julialang.org/u/florian)\
**Replies:** 1\
**Last updated:** [April 16, 2021, 7:15pm UTC](https://discourse.julialang.org/t/apply-transform-to-all-dataframe-columns-of-a-certain-type/59433 "2021-04-16T19:15:22Z")

</div>

What’s the ‘standard’ way to apply the transform function to all columns of a certain type in a DataFrame? For example, the best way to double all numeric columns I could come up with was: df = DataFrame(a="hello", b=1…

---

## [Help with register\_error\_hint](https://discourse.julialang.org/t/help-with-register-error-hint/56140)

<div class="topic-metadata">

**Author:** [@josePereiro](https://discourse.julialang.org/u/josePereiro)\
**Replies:** 5\
**Last updated:** [April 16, 2021, 6:34pm UTC](https://discourse.julialang.org/t/help-with-register-error-hint/56140 "2021-04-16T18:34:45Z")

</div>

Hi, I want to add some useful hints but for some reason I can’t trigger the callback for a UndefVarError exception. module Hinter only\_int(x::Int) = 1 any\_number(x::Number) = 2 function \_\_init\_\_() …

---

## [ArgumentError: Package Interact does not have Reexport in its dependencies](https://discourse.julialang.org/t/argumenterror-package-interact-does-not-have-reexport-in-its-dependencies/59211)

<div class="topic-metadata">

**Author:** [@kilyig](https://discourse.julialang.org/u/kilyig)\
**Replies:** 4\
**Last updated:** [April 16, 2021, 5:44pm UTC](https://discourse.julialang.org/t/argumenterror-package-interact-does-not-have-reexport-in-its-dependencies/59211 "2021-04-16T17:44:09Z")

</div>

Hello everyone, I have been struggling with this error for the past few weeks, and finally decided to ask it here. Background: I am trying to work on the Jupyter notebooks that supplement a course. These notebooks use…

---

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

<div class="topic-metadata">

**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")

</div>

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…

---

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

<div class="topic-metadata">

**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")

</div>

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…

[Previous page](https://discourse.julialang.org/c/usage/6.md?page=610)

[Next page](https://discourse.julialang.org/c/usage/6.md?page=612)