# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1299

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

**Page:** 1300

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## [Missing methods qr(A)' and qr(A') for sparse](https://discourse.julialang.org/t/missing-methods-qr-a-and-qr-a-for-sparse/66370)

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**Author:** [@Thomas](https://discourse.julialang.org/u/Thomas)\
**Replies:** 1\
**Last updated:** [August 14, 2021, 1:36am UTC](https://discourse.julialang.org/t/missing-methods-qr-a-and-qr-a-for-sparse/66370 "2021-08-14T01:36:24Z")

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Weird, that Base.runtests("LinearAlgebra/qr") passed, but I got this error (which I thought this has been fixed in https://github.com/JuliaLang/SuiteSparse.jl/issues/22) using LinearAlgebra, SparseArrays A = sprand(10,1…

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## [Editing titles after creating a Makie plot](https://discourse.julialang.org/t/editing-titles-after-creating-a-makie-plot/66352)

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**Author:** [@jlchan](https://discourse.julialang.org/u/jlchan)\
**Replies:** 6\
**Last updated:** [August 14, 2021, 12:05am UTC](https://discourse.julialang.org/t/editing-titles-after-creating-a-makie-plot/66352 "2021-08-14T00:05:48Z")

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I’m customizing Makie.plot to edit axis properties due to Accessing axis in Makie plot recipes. My function looks something like this: function foo(fig = Makie.Figure()) axes = \[Makie.Axis(fig\[i,j\]) for j in 1:3, i in…

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## [Row-wise mean of columns in a DataFrame](https://discourse.julialang.org/t/row-wise-mean-of-columns-in-a-dataframe/66358)

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**Author:** [@hdavid16](https://discourse.julialang.org/u/hdavid16)\
**Replies:** 4\
**Last updated:** [August 13, 2021, 11:58pm UTC](https://discourse.julialang.org/t/row-wise-mean-of-columns-in-a-dataframe/66358 "2021-08-13T23:58:49Z")

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I saw a post where @bkamins explained how to add a column that has the sum of the rows in selected columns ( (Julia) Assigning DataFrame column sum to a new column - Stack Overflow). Is there a way to use transform to do…

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## [How do you update VS Code in the best way?](https://discourse.julialang.org/t/how-do-you-update-vs-code-in-the-best-way/66116)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 4\
**Last updated:** [August 12, 2021, 6:15am UTC](https://discourse.julialang.org/t/how-do-you-update-vs-code-in-the-best-way/66116 "2021-08-12T06:15:38Z")

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Hi, I realise that this is just a generic VS Code question, and got nothing with Julia to do. But then I figured this is something people do often enough that several probably knows the answer, and it wouldn’t hurt to h…

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## [Julia should submit some lessons for hour of code](https://discourse.julialang.org/t/julia-should-submit-some-lessons-for-hour-of-code/66368)

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**Author:** [@spirit1jkm](https://discourse.julialang.org/u/spirit1jkm)\
**Replies:** 0\
**Last updated:** [August 13, 2021, 9:57pm UTC](https://discourse.julialang.org/t/julia-should-submit-some-lessons-for-hour-of-code/66368 "2021-08-13T21:57:28Z")

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Every year code.org gets students from all over to do an hour of code for Computer Science week in December. Julia should submit some online lesson modules designed for grades 6-12 to get Julia coming up with the next ge…

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## [Read a single element vs array from stream](https://discourse.julialang.org/t/read-a-single-element-vs-array-from-stream/66328)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 3\
**Last updated:** [August 13, 2021, 9:37pm UTC](https://discourse.julialang.org/t/read-a-single-element-vs-array-from-stream/66328 "2021-08-13T21:37:27Z")

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Since the single case is used often, I use read1T as a convenience function. Novice question: can the two functions be combined without violating type stability? Or, more generally, does Union{T, AbstractArray{T}} as i…

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## [Improving perfomance for a beginner](https://discourse.julialang.org/t/improving-perfomance-for-a-beginner/66353)

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**Author:** [@jpmorr](https://discourse.julialang.org/u/jpmorr)\
**Replies:** 3\
**Last updated:** [August 13, 2021, 8:35pm UTC](https://discourse.julialang.org/t/improving-perfomance-for-a-beginner/66353 "2021-08-13T20:35:09Z")

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I’ve recently started a side project at work to see if I can use julia to replace python for the majority of my data processing due to the possible gains in performance. Over the years the python code has become quite qu…

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## [A switch type function](https://discourse.julialang.org/t/a-switch-type-function/13491)

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**Author:** [@FiniteelementDuan](https://discourse.julialang.org/u/FiniteelementDuan)\
**Replies:** 18\
**Last updated:** [August 13, 2021, 8:16pm UTC](https://discourse.julialang.org/t/a-switch-type-function/13491 "2021-08-13T20:16:13Z")

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It seems that Julia doesn’t support a switch-case type function. I have the following code example, and it wouldn’t pass in Julia: Function Gauss(option) ##Here, option is a string if option ==‘L3’ a=0 end end Wha…

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## [More efficient way of getting permutations](https://discourse.julialang.org/t/more-efficient-way-of-getting-permutations/66356)

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**Author:** [@daviddoij](https://discourse.julialang.org/u/daviddoij)\
**Replies:** 3\
**Last updated:** [August 13, 2021, 8:07pm UTC](https://discourse.julialang.org/t/more-efficient-way-of-getting-permutations/66356 "2021-08-13T20:07:50Z")

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Hi there, the following piece of code gets the job done but it is not very efficient. Benchmarks throws: 0.018436 seconds (7.23 k allocations: 416.604 KiB, 99.90% compilation time) Timewise it’s ok but I’m wondering a…

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## [Isbits Without Propagation of Parametric Types?](https://discourse.julialang.org/t/isbits-without-propagation-of-parametric-types/66305)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 4\
**Last updated:** [August 13, 2021, 7:56pm UTC](https://discourse.julialang.org/t/isbits-without-propagation-of-parametric-types/66305 "2021-08-13T19:56:01Z")

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Consider this MWE: abstract type A end abstract type B \<: A end abstract type C \<: A end struct D{T \<: A} data::UInt8 end struct E a::D b::D c::D end struct F{T1 \<: D, T2 \<: D, T3 \<: D} a::T1 …

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## [Why modyfing view do not lead to modification of source array](https://discourse.julialang.org/t/why-modyfing-view-do-not-lead-to-modification-of-source-array/66354)

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**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 1\
**Last updated:** [August 13, 2021, 7:38pm UTC](https://discourse.julialang.org/t/why-modyfing-view-do-not-lead-to-modification-of-source-array/66354 "2021-08-13T19:38:23Z")

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Hello I have some 3 dimensional array (CT scan) - then for convinience I define view to given slice (slicing can be done in diffrent dimensions so that is why I have this meta.parse…). I want to be able to modify source …

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## [ANN: DataFramesMeta 0.9.0 release](https://discourse.julialang.org/t/ann-dataframesmeta-0-9-0-release/66342)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 1\
**Last updated:** [August 13, 2021, 5:41pm UTC](https://discourse.julialang.org/t/ann-dataframesmeta-0-9-0-release/66342 "2021-08-13T17:41:48Z")

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I am proud to announce the 0.9.0 release of DataFramesMeta.jl. We have three big changes inspired by DataFrameMacros.jl Better support for row-wise transformations: We now export @rtransform, @rselect, and @rsubset, a…

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## [Supertype of \`Dict\` with \`Vector{\<:Pair}\` as key values](https://discourse.julialang.org/t/supertype-of-dict-with-vector-pair-as-key-values/66345)

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**Author:** [@frankwswang](https://discourse.julialang.org/u/frankwswang)\
**Replies:** 0\
**Last updated:** [August 13, 2021, 3:27pm UTC](https://discourse.julialang.org/t/supertype-of-dict-with-vector-pair-as-key-values/66345 "2021-08-13T15:27:09Z")

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So I was trying to find the type of something like a Dict(1=\>\[:a=\>1\], 2=\>\[:b=\>2\]) for function argument type specification and it’s easy to see that since the key values are Vector{\<:Pair}, the Dict is a Dict{Int64, \<:Ve…

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## [GeoArrays band math](https://discourse.julialang.org/t/geoarrays-band-math/65947)

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**Author:** [@KrOstir](https://discourse.julialang.org/u/KrOstir)\
**Replies:** 7\
**Last updated:** [August 13, 2021, 3:15pm UTC](https://discourse.julialang.org/t/geoarrays-band-math/65947 "2021-08-13T15:15:20Z")

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I am working with an GeoArray and would like to perform band maths with it, i.e. compute NDVI from bands. I am currently doing the following: # Read Sentinel-2 data fn = download("https://bitbucket.org/earthobservation/…

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## [GPU-Kernel function for fast matrix multiplication using shared memory](https://discourse.julialang.org/t/gpu-kernel-function-for-fast-matrix-multiplication-using-shared-memory/66341)

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**Author:** [@DanielZ](https://discourse.julialang.org/u/DanielZ)\
**Replies:** 1\
**Last updated:** [August 13, 2021, 2:08pm UTC](https://discourse.julialang.org/t/gpu-kernel-function-for-fast-matrix-multiplication-using-shared-memory/66341 "2021-08-13T14:08:20Z")

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\[Copied from a Slack-Conversation:\] Me (Daniel): Hello, we try to implement a matrix multiplication in a kernel function using shared memory. However, our code in the kernel\_matmul\_fast function calculates a wrong resu…

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## [How to define a function such that its arguments can mutate?](https://discourse.julialang.org/t/how-to-define-a-function-such-that-its-arguments-can-mutate/66320)

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**Author:** [@CRquantum](https://discourse.julialang.org/u/CRquantum)\
**Replies:** 16\
**Last updated:** [August 13, 2021, 1:59pm UTC](https://discourse.julialang.org/t/how-to-define-a-function-such-that-its-arguments-can-mutate/66320 "2021-08-13T13:59:22Z")

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A stupid question, I just want to have a function which is like a subroutine in Fortran. Just a simple example, function gauss(theta::Array{Float64,2}) theta = \[1.0 1.0 ; 2.0 2.0\] return nothing end I just want to inp…

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## [Code parallelization for Brownian Dynamics simulation of hard spheres](https://discourse.julialang.org/t/code-parallelization-for-brownian-dynamics-simulation-of-hard-spheres/64584)

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**Author:** [@Amir\_Abbasi](https://discourse.julialang.org/u/Amir_Abbasi)\
**Replies:** 5\
**Last updated:** [August 13, 2021, 1:47pm UTC](https://discourse.julialang.org/t/code-parallelization-for-brownian-dynamics-simulation-of-hard-spheres/64584 "2021-08-13T13:47:07Z")

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Hi All! I am using Julia to do Brownian dynamics simulation of many hard spheres in 2D and 3D (employing the repulsive LJ interaction). My code is mostly based on SoftSquishymatter.jl package, but the main difference is…

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## [Row number in DataFrames groupby query](https://discourse.julialang.org/t/row-number-in-dataframes-groupby-query/57319)

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**Author:** [@bdeonovic](https://discourse.julialang.org/u/bdeonovic)\
**Replies:** 5\
**Last updated:** [August 13, 2021, 1:30pm UTC](https://discourse.julialang.org/t/row-number-in-dataframes-groupby-query/57319 "2021-08-13T13:30:10Z")

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I’m trying to understand how to do data manipulations in DataFrames (+ Query or + DataFramesMeta or +LINQ), in particular today I am looking to get rownumber in a groupby query For MWE consider df = DataFrame(a=repeat(…

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## [C++: "The Day The Standard Library Died", anything to learn from the ABI vote/concern?](https://discourse.julialang.org/t/c-the-day-the-standard-library-died-anything-to-learn-from-the-abi-vote-concern/66312)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 4\
**Last updated:** [August 13, 2021, 1:02pm UTC](https://discourse.julialang.org/t/c-the-day-the-standard-library-died-anything-to-learn-from-the-abi-vote-concern/66312 "2021-08-13T13:02:47Z")

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https://cor3ntin.github.io/posts/abi/ the C++ committee took a series of polls on whether to break ABI, and decided not to. There was no applause. \[…\] Why do we want to break ABI Making associative container (much)…

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## [Combining multiple-shooting with out-of-ODE multithreading](https://discourse.julialang.org/t/combining-multiple-shooting-with-out-of-ode-multithreading/66338)

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**Author:** [@cmarcotte](https://discourse.julialang.org/u/cmarcotte)\
**Replies:** 1\
**Last updated:** [August 13, 2021, 12:05pm UTC](https://discourse.julialang.org/t/combining-multiple-shooting-with-out-of-ode-multithreading/66338 "2021-08-13T12:05:41Z")

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DiffEqFlux has examples for multiple shooting and out-of-ODE multithreading here and here, respectively. This seems like a natural pairing, but it seems like multiple\_shoot is written for a completely serial implementat…

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## [Create an array using the output of size()](https://discourse.julialang.org/t/create-an-array-using-the-output-of-size/66326)

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**Author:** [@Bardo](https://discourse.julialang.org/u/Bardo)\
**Replies:** 4\
**Last updated:** [August 13, 2021, 11:15am UTC](https://discourse.julialang.org/t/create-an-array-using-the-output-of-size/66326 "2021-08-13T11:15:33Z")

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Matlab: a = -1.3077 3.5784 3.0349 -0.4336 2.7694 0.7254 0.3426 -1.3499 -0.0631 \>\> zeros(size(a)) ans = 0 0 0 0 0 0 0 0 0 julia\> a 3×3 Matrix{Float64}…

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## [Build a package deps/build.jl](https://discourse.julialang.org/t/build-a-package-deps-build-jl/56771)

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**Author:** [@Paht\_J](https://discourse.julialang.org/u/Paht_J)\
**Replies:** 2\
**Last updated:** [August 13, 2021, 10:07am UTC](https://discourse.julialang.org/t/build-a-package-deps-build-jl/56771 "2021-08-13T10:07:04Z")

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Does anyone know how to build a package? The documentation is not helpful It says that I should use dep/build.jl but never describes or shows an example of what is in that file. What would be a good reference? Pkg · The…

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## [Bridging (Gitter, Slack, IRC etc)](https://discourse.julialang.org/t/bridging-gitter-slack-irc-etc/7888)

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**Author:** [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Replies:** 2\
**Last updated:** [August 13, 2021, 9:55am UTC](https://discourse.julialang.org/t/bridging-gitter-slack-irc-etc/7888 "2021-08-13T09:55:40Z")

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It occurs to me that the current setup is not written down anywhere, except in (now gone) messages in Community on Slack. It is a bit different to what is on the old mailing list. I figure I should write it down in ca…

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## [Inferable unpacking of Tuple type to tuple of types](https://discourse.julialang.org/t/inferable-unpacking-of-tuple-type-to-tuple-of-types/66329)

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**Author:** [@juthohaegeman](https://discourse.julialang.org/u/juthohaegeman)\
**Replies:** 2\
**Last updated:** [August 13, 2021, 9:45am UTC](https://discourse.julialang.org/t/inferable-unpacking-of-tuple-type-to-tuple-of-types/66329 "2021-08-13T09:45:42Z")

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In one of my packages, I used the following paradigm to unpack a Tuple{T1,T2,...} into a tuple of the types unpack(::Type{Tuple{}}) = () unpack(::Type{T}) where {T\<:Tuple} = (Base.tuple\_type\_head(T), unpack(Base.tupe\_ty…

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## [How to exactly lock the type of the arguments of a function?](https://discourse.julialang.org/t/how-to-exactly-lock-the-type-of-the-arguments-of-a-function/66325)

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**Author:** [@CRquantum](https://discourse.julialang.org/u/CRquantum)\
**Replies:** 11\
**Last updated:** [August 13, 2021, 9:13am UTC](https://discourse.julialang.org/t/how-to-exactly-lock-the-type-of-the-arguments-of-a-function/66325 "2021-08-13T09:13:00Z")

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Another stupid question, I have a function function gauss(beta::Array{Float64,1}) beta .= \[1.0 2.0; 3.0 3.0\] return nothing end I set beta in the argument as a 1D array, however I set beta in the function as a 2D arra…

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## [Vector of Atomics](https://discourse.julialang.org/t/vector-of-atomics/64984)

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**Author:** [@nabla](https://discourse.julialang.org/u/nabla)\
**Replies:** 3\
**Last updated:** [August 13, 2021, 8:27am UTC](https://discourse.julialang.org/t/vector-of-atomics/64984 "2021-08-13T08:27:19Z")

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I’m aware of the Atomic{Int8} type, which wraps an Int8 into an atomically modifiable value. Internally, this is a mutable struct containing the Int8, and it seems to be the only possibility since by nature the Int8 must…

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## [Gradient of expression with JuMP variables](https://discourse.julialang.org/t/gradient-of-expression-with-jump-variables/66259)

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**Author:** [@ver\_kh](https://discourse.julialang.org/u/ver_kh)\
**Replies:** 3\
**Last updated:** [August 13, 2021, 7:16am UTC](https://discourse.julialang.org/t/gradient-of-expression-with-jump-variables/66259 "2021-08-13T07:16:53Z")

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Hi! I have a complex nonlinear expression built with JuMP variables. And now I want to find gradient of this expression with respect to these variables. What package will be helpful in this situation?

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## [AssertionError GCNConv FeaturedGraph GeometricFlux](https://discourse.julialang.org/t/assertionerror-gcnconv-featuredgraph-geometricflux/66061)

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**Author:** [@riegel\_gestr](https://discourse.julialang.org/u/riegel_gestr)\
**Replies:** 1\
**Last updated:** [August 13, 2021, 7:09am UTC](https://discourse.julialang.org/t/assertionerror-gcnconv-featuredgraph-geometricflux/66061 "2021-08-13T07:09:24Z")

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I am trying the GeometricFlux library by doing some test (coming from torch\_geometric). So test that I am doing is a simple graphs classification and I have considered very simple input: N = 100 k = 10 g = erdos\_renyi(…

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## [Manning liveProject on data science with Julia](https://discourse.julialang.org/t/manning-liveproject-on-data-science-with-julia/65692)

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**Author:** [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Replies:** 5\
**Last updated:** [August 13, 2021, 6:04am UTC](https://discourse.julialang.org/t/manning-liveproject-on-data-science-with-julia/65692 "2021-08-13T06:04:52Z")

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I am soon releasing a liveProject with Manning on doing data science with Julia. You can find the link to it here. The liveProject is - as its name says - project oriented, so expect it to be challenging for someone jus…

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## [Loading touchstone (.snp) files](https://discourse.julialang.org/t/loading-touchstone-snp-files/66012)

<div class="topic-metadata">

**Author:** [@Valery](https://discourse.julialang.org/u/Valery)\
**Replies:** 8\
**Last updated:** [August 13, 2021, 4:03am UTC](https://discourse.julialang.org/t/loading-touchstone-snp-files/66012 "2021-08-13T04:03:08Z")

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At the moment, what is the most convenient way to load touchstone (.snp) files in Julia ? I typically want to load scattering parameter of a multi-channel array extracted from software like Advanced Software Design (ADS…

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