# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1038

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

**Page:** 1039

---

## [ModelingToolkit systems from the XML file](https://discourse.julialang.org/t/modelingtoolkit-systems-from-the-xml-file/80991)

<div class="topic-metadata">

**Author:** [@mzhenirovskyy](https://discourse.julialang.org/u/mzhenirovskyy)\
**Replies:** 6\
**Last updated:** [May 16, 2022, 7:36pm UTC](https://discourse.julialang.org/t/modelingtoolkit-systems-from-the-xml-file/80991 "2022-05-16T19:36:19Z")

</div>

Hi All, From this link https://help.juliahub.com/JuliaSim/Tutorials/FMUs/ I can see that we can generate FMU and XML from ModelingToolkit. The question is: can we do a vice verse, get ModelingToolkit systems from the…

---

## [Help understanding solves with sparse cholesky factors](https://discourse.julialang.org/t/help-understanding-solves-with-sparse-cholesky-factors/81165)

<div class="topic-metadata">

**Author:** [@cgeoga](https://discourse.julialang.org/u/cgeoga)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 7:28pm UTC](https://discourse.julialang.org/t/help-understanding-solves-with-sparse-cholesky-factors/81165 "2022-05-16T19:28:55Z")

</div>

I recognize there are a few threads about this or something similar already, but I would really appreciate some clarification on something. I am aware that cholesky for sparse matrices permutes, and that you can ostensib…

---

## [MethodError: Cannot \`convert\` an object of type String7 to an object of type Float32](https://discourse.julialang.org/t/methoderror-cannot-convert-an-object-of-type-string7-to-an-object-of-type-float32/81163)

<div class="topic-metadata">

**Author:** [@Hupdup](https://discourse.julialang.org/u/Hupdup)\
**Replies:** 1\
**Last updated:** [May 16, 2022, 6:46pm UTC](https://discourse.julialang.org/t/methoderror-cannot-convert-an-object-of-type-string7-to-an-object-of-type-float32/81163 "2022-05-16T18:46:22Z")

</div>

Hi, I am writing a custom environment for a Reinforcement learning project. At every Timestep some Data is used to determine a part of the state/next state. I want to put this data in with a CSV file, but when I want to…

---

## [Any way to plot non-orthogonal axis in Julia?](https://discourse.julialang.org/t/any-way-to-plot-non-orthogonal-axis-in-julia/81161)

<div class="topic-metadata">

**Author:** [@chunjiw](https://discourse.julialang.org/u/chunjiw)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 6:42pm UTC](https://discourse.julialang.org/t/any-way-to-plot-non-orthogonal-axis-in-julia/81161 "2022-05-16T18:42:32Z")

</div>

Something like this

---

## [Benchmarks for our own new differential equation solver](https://discourse.julialang.org/t/benchmarks-for-our-own-new-differential-equation-solver/81109)

<div class="topic-metadata">

**Author:** [@Mikel\_Antonana](https://discourse.julialang.org/u/Mikel_Antonana)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 5:31pm UTC](https://discourse.julialang.org/t/benchmarks-for-our-own-new-differential-equation-solver/81109 "2022-05-16T17:31:11Z")

</div>

Hi everyone, We are developing a new differential equation solver, function DiffEqBase.\_\_solve(prob::DiffEqBase.AbstractODEProblem{uType,tType,isinplace}, alg::IRKAlgorithm, udim::Array{floatType,dim},args...; …

---

## [Getting the functional form of a pdf using Kernel density estimation](https://discourse.julialang.org/t/getting-the-functional-form-of-a-pdf-using-kernel-density-estimation/81158)

<div class="topic-metadata">

**Author:** [@devanshu](https://discourse.julialang.org/u/devanshu)\
**Replies:** 0\
**Last updated:** [May 16, 2022, 5:24pm UTC](https://discourse.julialang.org/t/getting-the-functional-form-of-a-pdf-using-kernel-density-estimation/81158 "2022-05-16T17:24:10Z")

</div>

Hi, I have obtained sampled data points through some numerical calculations, and I want to estimate its pdf. Using KernelDensity.jl package, it is possible to estimate the KDE which can be used for visualization, however…

---

## [Adding nodata value to ArchGDAL dataset](https://discourse.julialang.org/t/adding-nodata-value-to-archgdal-dataset/81142)

<div class="topic-metadata">

**Author:** [@sunayana](https://discourse.julialang.org/u/sunayana)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 4:25pm UTC](https://discourse.julialang.org/t/adding-nodata-value-to-archgdal-dataset/81142 "2022-05-16T16:25:04Z")

</div>

Hello, I am trying to setnodatavalue! while creating a dataset, I do not see how to do this with the API. I see it is possible for a RasterBand object. Could someone point be to am example of ArchGDAL where nodata value…

---

## [Makie.jl: colormap without coarse graining](https://discourse.julialang.org/t/makie-jl-colormap-without-coarse-graining/81130)

<div class="topic-metadata">

**Author:** [@Kevin\_Kleinbeck](https://discourse.julialang.org/u/Kevin_Kleinbeck)\
**Replies:** 4\
**Last updated:** [May 16, 2022, 3:48pm UTC](https://discourse.julialang.org/t/makie-jl-colormap-without-coarse-graining/81130 "2022-05-16T15:48:51Z")

</div>

Motivation I have a function f on a 2d domain, which approximatively has a minimal negative value -1 and a maximal positive value of \\approx 1/4 (not really important), which I want to visualise in a way, such that f \\ap…

---

## [Unable to eliminate an unwanted allocation](https://discourse.julialang.org/t/unable-to-eliminate-an-unwanted-allocation/80966)

<div class="topic-metadata">

**Author:** [@peremato](https://discourse.julialang.org/u/peremato)\
**Replies:** 23\
**Last updated:** [May 16, 2022, 3:35pm UTC](https://discourse.julialang.org/t/unable-to-eliminate-an-unwanted-allocation/80966 "2022-05-16T15:35:44Z")

</div>

I have spend several hours to eliminate a very elusive allocation that happens in a package that I intend to run on a GPU, which any allocation is fatal. I have tried all the standard methods to eliminate it (@code\_warnt…

---

## [Disable instability checks in OrdinaryDiffEq](https://discourse.julialang.org/t/disable-instability-checks-in-ordinarydiffeq/80799)

<div class="topic-metadata">

**Author:** [@AndreaRH](https://discourse.julialang.org/u/AndreaRH)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 1:58pm UTC](https://discourse.julialang.org/t/disable-instability-checks-in-ordinarydiffeq/80799 "2022-05-16T13:58:56Z")

</div>

Hi, I have a small network of 3 neurons and I’m using OrdinaryDiffEq to solve the ode system describing their interconnected dynamics. Since this problem is stiff, I’m using an adaptive solver that can handle it and thi…

---

## [How can I read back a delimited file with mixed column types involving vectors](https://discourse.julialang.org/t/how-can-i-read-back-a-delimited-file-with-mixed-column-types-involving-vectors/81082)

<div class="topic-metadata">

**Author:** [@liuyxpp](https://discourse.julialang.org/u/liuyxpp)\
**Replies:** 10\
**Last updated:** [May 16, 2022, 1:51pm UTC](https://discourse.julialang.org/t/how-can-i-read-back-a-delimited-file-with-mixed-column-types-involving-vectors/81082 "2022-05-16T13:51:04Z")

</div>

Say I have data in the following format v = \[(1, 0.1, \[1, 2, 3\]), (2, 0.2, \[3,4,5\])\] I can write it to a delimited file using using DelimitedFiles open("test.csv", w) do io writedlm(io, v) end The content of tes…

---

## [How to measure performance with @time?](https://discourse.julialang.org/t/how-to-measure-performance-with-time/81150)

<div class="topic-metadata">

**Author:** [@vamp](https://discourse.julialang.org/u/vamp)\
**Replies:** 3\
**Last updated:** [May 16, 2022, 1:48pm UTC](https://discourse.julialang.org/t/how-to-measure-performance-with-time/81150 "2022-05-16T13:48:47Z")

</div>

Hello, I want to measure how long the following solver takes: #Q-Learning solver q\_learning\_solver = QLearningSolver(n\_episodes=1000, max\_episode\_length = 1000, …

---

## [Shallow copy of an arbitrary mutable object](https://discourse.julialang.org/t/shallow-copy-of-an-arbitrary-mutable-object/81140)

<div class="topic-metadata">

**Author:** [@whatsthecraic](https://discourse.julialang.org/u/whatsthecraic)\
**Replies:** 1\
**Last updated:** [May 16, 2022, 1:45pm UTC](https://discourse.julialang.org/t/shallow-copy-of-an-arbitrary-mutable-object/81140 "2022-05-16T13:45:38Z")

</div>

Hi there, is there any method to perform a shallow copy of a mutable object? My attempt of Base.copy(obj) failed with an error MethodError: no method matching copy(::MyArbitraryType)

---

## [Using a range in Symbolics.jl](https://discourse.julialang.org/t/using-a-range-in-symbolics-jl/81139)

<div class="topic-metadata">

**Author:** [@hughjonesd](https://discourse.julialang.org/u/hughjonesd)\
**Replies:** 1\
**Last updated:** [May 16, 2022, 1:44pm UTC](https://discourse.julialang.org/t/using-a-range-in-symbolics-jl/81139 "2022-05-16T13:44:16Z")

</div>

I’m playing with Symbolics.jl. I’d like to define a function which sums items over a range, e.g. @variables a b sumsq(a, b) = sum(l -\> l^2, a:b) @register sumsq Reading Frequently Asked Questions · Symbolics.jl makes m…

---

## [Get results from CBC solver for optimization](https://discourse.julialang.org/t/get-results-from-cbc-solver-for-optimization/81135)

<div class="topic-metadata">

**Author:** [@ayodyas](https://discourse.julialang.org/u/ayodyas)\
**Replies:** 4\
**Last updated:** [May 16, 2022, 11:43am UTC](https://discourse.julialang.org/t/get-results-from-cbc-solver-for-optimization/81135 "2022-05-16T11:43:43Z")

</div>

I would like to know how to access the results (constraints value, variable value) from the model created using Cbc and Jump model in Julia

---

## [Help with different terms in documentation](https://discourse.julialang.org/t/help-with-different-terms-in-documentation/81141)

<div class="topic-metadata">

**Author:** [@vamp](https://discourse.julialang.org/u/vamp)\
**Replies:** 0\
**Last updated:** [May 16, 2022, 10:12am UTC](https://discourse.julialang.org/t/help-with-different-terms-in-documentation/81141 "2022-05-16T10:12:22Z")

</div>

Hello, I am using the POMDPs.jl package, link here. I am trying to inderstand the difference bewtwen POMDPs.isterminal — Function and TerminalState. I know they can be used together, but in my case I need to use termin…

---

## [Sparse solve vs BandedMatrix; time and allocation surprise](https://discourse.julialang.org/t/sparse-solve-vs-bandedmatrix-time-and-allocation-surprise/45119)

<div class="topic-metadata">

**Author:** [@ctkelley](https://discourse.julialang.org/u/ctkelley)\
**Replies:** 29\
**Last updated:** [May 16, 2022, 9:47am UTC](https://discourse.julialang.org/t/sparse-solve-vs-bandedmatrix-time-and-allocation-surprise/45119 "2022-05-16T09:47:22Z")

</div>

I’m trying to understand why the SparseSuite \\ is so much worse than what I get with BandedMatrices. My test case, which reflects the results of my application, uses two matrices with the same elements, but stored diffe…

---

## [Jump process with multiple jumps, which jump occurs?](https://discourse.julialang.org/t/jump-process-with-multiple-jumps-which-jump-occurs/81122)

<div class="topic-metadata">

**Author:** [@Max\_Beez](https://discourse.julialang.org/u/Max_Beez)\
**Replies:** 1\
**Last updated:** [May 16, 2022, 9:21am UTC](https://discourse.julialang.org/t/jump-process-with-multiple-jumps-which-jump-occurs/81122 "2022-05-16T09:21:08Z")

</div>

If we construct a jump process, say one with an underlying ODE and 5 jumps are defined with differing affects. We then pass the jumps, say j1,j2, j3, j4 and j5 to the JumpProblem constructor. How is which jump occurs im…

---

## [Exportall might be useful in some (limited) cases?](https://discourse.julialang.org/t/exportall-might-be-useful-in-some-limited-cases/80872)

<div class="topic-metadata">

**Author:** [@jsjie](https://discourse.julialang.org/u/jsjie)\
**Replies:** 9\
**Last updated:** [May 16, 2022, 8:18am UTC](https://discourse.julialang.org/t/exportall-might-be-useful-in-some-limited-cases/80872 "2022-05-16T08:18:52Z")

</div>

There are many good points against common use of exportall: possible name conflicts when importing from different packages with explicit export, we know what symbols are intended for internal uses only, and what are in…

---

## [Parse constant from enviroment - macro parameter string interpolation](https://discourse.julialang.org/t/parse-constant-from-enviroment-macro-parameter-string-interpolation/81133)

<div class="topic-metadata">

**Author:** [@FireCrumb](https://discourse.julialang.org/u/FireCrumb)\
**Replies:** 3\
**Last updated:** [May 16, 2022, 8:01am UTC](https://discourse.julialang.org/t/parse-constant-from-enviroment-macro-parameter-string-interpolation/81133 "2022-05-16T08:01:18Z")

</div>

I have some global constants which I want to read from ENV or define with a default value. I pass a parameter to the macro and want to put it into a string in the output expression. When I use "$($name)" then I get "$(…

---

## [How to apply a decay for learning rate?](https://discourse.julialang.org/t/how-to-apply-a-decay-for-learning-rate/81108)

<div class="topic-metadata">

**Author:** [@vamp](https://discourse.julialang.org/u/vamp)\
**Replies:** 5\
**Last updated:** [May 16, 2022, 7:18am UTC](https://discourse.julialang.org/t/how-to-apply-a-decay-for-learning-rate/81108 "2022-05-16T07:18:13Z")

</div>

Hello, I am very new to Julia, so I apologize if I do not explain the problem correctly (feel free to ask me). I am trying to use this solvers. For the exploration\_policy I can use a decay with exploration\_policy= EpsG…

---

## [Stipple Data Processing](https://discourse.julialang.org/t/stipple-data-processing/81120)

<div class="topic-metadata">

**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 2\
**Last updated:** [May 16, 2022, 6:16am UTC](https://discourse.julialang.org/t/stipple-data-processing/81120 "2022-05-16T06:16:19Z")

</div>

It will be great if there is an example demonstrating how you can upload and process a CSV file. For example, it will be nice to show you can upload a custom CSV file to perform k-means clustering using the example Stip…

---

## [Macro to "steal" types from another package](https://discourse.julialang.org/t/macro-to-steal-types-from-another-package/80585)

<div class="topic-metadata">

**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 6\
**Last updated:** [May 16, 2022, 1:07am UTC](https://discourse.julialang.org/t/macro-to-steal-types-from-another-package/80585 "2022-05-16T01:07:15Z")

</div>

Package A defines a bunch of types whose interface I would like to extend in Package B. However, to do this in a straightforward way, Package B requires those types to subtype B.SomeAbstractType. To mitigate this I am pl…

---

## [Can't read a CSV file with empty fields into a DataFrame](https://discourse.julialang.org/t/cant-read-a-csv-file-with-empty-fields-into-a-dataframe/80276)

<div class="topic-metadata">

**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 7\
**Last updated:** [May 16, 2022, 12:06am UTC](https://discourse.julialang.org/t/cant-read-a-csv-file-with-empty-fields-into-a-dataframe/80276 "2022-05-16T00:06:08Z")

</div>

I am trying to read a CSV file into a DataFrame. It clearly has some empty fields, and I get an error ERROR: MethodError: Cannot convert an object of type Missing to an object of type String I have tried to redefine …

---

## [Understending \`dims\` kwarg](https://discourse.julialang.org/t/understending-dims-kwarg/81121)

<div class="topic-metadata">

**Author:** [@eliascarv](https://discourse.julialang.org/u/eliascarv)\
**Replies:** 1\
**Last updated:** [May 15, 2022, 11:55pm UTC](https://discourse.julialang.org/t/understending-dims-kwarg/81121 "2022-05-15T23:55:51Z")

</div>

When I use mean function with dims=1 (the row dimension) in a matrix, the mean of each column is returned. Example: julia\> using Statistics julia\> a = \[3 5 4 5 9 8 4 9 9 9 5 6\] 3×4 Mat…

---

## [Excessive compilation time](https://discourse.julialang.org/t/excessive-compilation-time/81114)

<div class="topic-metadata">

**Author:** [@Jean\_Michel](https://discourse.julialang.org/u/Jean_Michel)\
**Replies:** 6\
**Last updated:** [May 15, 2022, 10:02pm UTC](https://discourse.julialang.org/t/excessive-compilation-time/81114 "2022-05-15T22:02:36Z")

</div>

I have a problem with excessive compilation time. The problem is with code automatically translated from another system (gap3) so I cannot easily change it. As an example, the function below takes 2 minutes to compile; a…

---

## [FFT with variable sampling frequency](https://discourse.julialang.org/t/fft-with-variable-sampling-frequency/46288)

<div class="topic-metadata">

**Author:** [@EmadMasroor](https://discourse.julialang.org/u/EmadMasroor)\
**Replies:** 11\
**Last updated:** [May 15, 2022, 9:51pm UTC](https://discourse.julialang.org/t/fft-with-variable-sampling-frequency/46288 "2022-05-15T21:51:56Z")

</div>

Hello members of the Julia community, Is it possible to use the FFTW package (or any other Julia package) to perform an FFT on non-uniformly-sampled data? It seems that the functions provided in this package all assume …

---

## [Flux.destructure a Flux.Chain that takes an argument?](https://discourse.julialang.org/t/flux-destructure-a-flux-chain-that-takes-an-argument/81067)

<div class="topic-metadata">

**Author:** [@linkz](https://discourse.julialang.org/u/linkz)\
**Replies:** 6\
**Last updated:** [May 15, 2022, 9:47pm UTC](https://discourse.julialang.org/t/flux-destructure-a-flux-chain-that-takes-an-argument/81067 "2022-05-15T21:47:48Z")

</div>

Hello all, I have a use case where I need to use some custom layers in a Flux.Chain that depend on the initial vector passed to the chain (which changes). I can construct the chain easily as per below (with some dummy la…

---

## [How to use ForwardDiff with NLopt?](https://discourse.julialang.org/t/how-to-use-forwarddiff-with-nlopt/53368)

<div class="topic-metadata">

**Author:** [@Michael\_Barmann](https://discourse.julialang.org/u/Michael_Barmann)\
**Replies:** 9\
**Last updated:** [May 15, 2022, 9:06pm UTC](https://discourse.julialang.org/t/how-to-use-forwarddiff-with-nlopt/53368 "2022-05-15T21:06:14Z")

</div>

I’m working on an optimization problem, and I’m trying to make use of the gradient-based algorithms in the NLopt library (specifically LD\_SLSQP). The objective function which I am trying to minimize does not have an anal…

---

## [How to add point size to a Gadfly scatter plot based on a variable](https://discourse.julialang.org/t/how-to-add-point-size-to-a-gadfly-scatter-plot-based-on-a-variable/81111)

<div class="topic-metadata">

**Author:** [@Brinkhuis](https://discourse.julialang.org/u/Brinkhuis)\
**Replies:** 2\
**Last updated:** [May 15, 2022, 8:13pm UTC](https://discourse.julialang.org/t/how-to-add-point-size-to-a-gadfly-scatter-plot-based-on-a-variable/81111 "2022-05-15T20:13:11Z")

</div>

I am trying to reproduce this Seaborn plot using Gadfly. The code I have so far is: using CSV, DataFrames, Gadfly download("https://raw.githubusercontent.com/mwaskom/seaborn-data/master/mpg.csv", "mpg.csv"); mpg = Dat…

[Previous page](https://discourse.julialang.org/latest.md?page=1037)

[Next page](https://discourse.julialang.org/latest.md?page=1039)