# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1094

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

**Page:** 1095

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## [Get the number of rows updated in SQLite?](https://discourse.julialang.org/t/get-the-number-of-rows-updated-in-sqlite/78023)

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**Author:** [@taotree](https://discourse.julialang.org/u/taotree)\
**Replies:** 0\
**Last updated:** [March 17, 2022, 12:58pm UTC](https://discourse.julialang.org/t/get-the-number-of-rows-updated-in-sqlite/78023 "2022-03-17T12:58:20Z")

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In other languages I’ve used, after running update SQL, it returns the number of rows updated. However, when I run DBInterface.execute("update Test set val='green' where id=1"), it seems to return nothing. Is there a way…

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## [1 + 'a' = 'b'](https://discourse.julialang.org/t/1-a-b/77947)

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**Author:** [@Jerry](https://discourse.julialang.org/u/Jerry)\
**Replies:** 81\
**Last updated:** [March 17, 2022, 11:48am UTC](https://discourse.julialang.org/t/1-a-b/77947 "2022-03-17T11:48:39Z")

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julia\> 1 + 'a' 'b': ASCII/Unicode U+0062 (category Ll: Letter, lowercase) This is ridiculous. How is this not an error? There should be—and maybe there is—an increment function for characters. I know this aggressive beh…

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## [How to get the state of a dynamic system during integration?](https://discourse.julialang.org/t/how-to-get-the-state-of-a-dynamic-system-during-integration/78016)

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**Author:** [@egor](https://discourse.julialang.org/u/egor)\
**Replies:** 15\
**Last updated:** [March 17, 2022, 11:04am UTC](https://discourse.julialang.org/t/how-to-get-the-state-of-a-dynamic-system-during-integration/78016 "2022-03-17T11:04:44Z")

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Hello everyone, I am calculating Lyapunov exponents for my system using lyapunovspectrum from DynamicalSystems. Can I somehow get the state of the system during integration? For another system, I wrote this code: check …

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## [How to get a quick description of a vector/matrix like \`pd.DataFrame.describe\`](https://discourse.julialang.org/t/how-to-get-a-quick-description-of-a-vector-matrix-like-pd-dataframe-describe/78013)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 6\
**Last updated:** [March 17, 2022, 10:57am UTC](https://discourse.julialang.org/t/how-to-get-a-quick-description-of-a-vector-matrix-like-pd-dataframe-describe/78013 "2022-03-17T10:57:08Z")

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When in python pandas I find pd.DataFrame.describe a helpful tool to get some quick insight about my DataFrame, particularly when using large DataFrames in the REPL. It works as follows, from the linked docs: \>\>\> s = pd…

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## [Installing Julia from source on WSL halts for an infinite time](https://discourse.julialang.org/t/installing-julia-from-source-on-wsl-halts-for-an-infinite-time/77923)

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**Author:** [@Saransh-cpp](https://discourse.julialang.org/u/Saransh-cpp)\
**Replies:** 16\
**Last updated:** [March 17, 2022, 10:27am UTC](https://discourse.julialang.org/t/installing-julia-from-source-on-wsl-halts-for-an-infinite-time/77923 "2022-03-17T10:27:56Z")

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I have been trying to install Julia from the source on WSL by following the steps mentioned here - https://github.com/JuliaLang/julia/blob/master/doc/src/devdocs/build/windows.md - but the installation stops in between a…

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## [How to make empty dataframe with column names?](https://discourse.julialang.org/t/how-to-make-empty-dataframe-with-column-names/77936)

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**Author:** [@rmsmsgood](https://discourse.julialang.org/u/rmsmsgood)\
**Replies:** 5\
**Last updated:** [March 17, 2022, 10:21am UTC](https://discourse.julialang.org/t/how-to-make-empty-dataframe-with-column-names/77936 "2022-03-17T10:21:19Z")

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df = DataFrame(x = \[\], y = String\[\]) 0×2 DataFrame I know that empty dataframe with column names, but if i have long column names below, how can i make the empty dataframe? julia\> nodenames 224-element Vecto…

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## [Numerical computation of continuous Fourier transforms](https://discourse.julialang.org/t/numerical-computation-of-continuous-fourier-transforms/77999)

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**Author:** [@DanielVandH](https://discourse.julialang.org/u/DanielVandH)\
**Replies:** 3\
**Last updated:** [March 17, 2022, 10:05am UTC](https://discourse.julialang.org/t/numerical-computation-of-continuous-fourier-transforms/77999 "2022-03-17T10:05:45Z")

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Are there any packages available for computation of Fourier transforms of the form F(x\_k) = \\int\_{-\\infty}^\\infty f(t)\\mathrm{e}^{-\\mathrm{i}tx\_k}\\,\\mathrm{d}t? e.g. the method developed by DBailey and Swarztrauber (The …

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## [Why is Julia's graphics system so slow?](https://discourse.julialang.org/t/why-is-julias-graphics-system-so-slow/68750)

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**Author:** [@aachener](https://discourse.julialang.org/u/aachener)\
**Replies:** 32\
**Last updated:** [March 17, 2022, 8:59am UTC](https://discourse.julialang.org/t/why-is-julias-graphics-system-so-slow/68750 "2022-03-17T08:59:14Z")

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Hi, all, I am relatively new to Julia, and am using Julia 1.6.2 as well as newest Plots.jl, pyplot.jl and Gadfly.jl. I am programming Julia using vs code extension. I find that drawing charts and plots in Julia is par…

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## [How to deal with inconsistent objects due to mutation](https://discourse.julialang.org/t/how-to-deal-with-inconsistent-objects-due-to-mutation/77960)

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**Author:** [@pablosanjose](https://discourse.julialang.org/u/pablosanjose)\
**Replies:** 19\
**Last updated:** [March 17, 2022, 7:58am UTC](https://discourse.julialang.org/t/how-to-deal-with-inconsistent-objects-due-to-mutation/77960 "2022-03-17T07:58:42Z")

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This is a bit of a basic philosophical question about type and API design. I would love the input of more experienced coders, since I suspect I might be approaching my problem wrong. I have a type in essence similar to: …

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## [How to debug julia callback function which passed to a C lib](https://discourse.julialang.org/t/how-to-debug-julia-callback-function-which-passed-to-a-c-lib/78007)

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**Author:** [@linanisyugioh](https://discourse.julialang.org/u/linanisyugioh)\
**Replies:** 1\
**Last updated:** [March 17, 2022, 6:48am UTC](https://discourse.julialang.org/t/how-to-debug-julia-callback-function-which-passed-to-a-c-lib/78007 "2022-03-17T06:48:22Z")

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I recorded a video to show the process of debug. In this video, you can obviously see that the debugger cannot hit the breakpoint in a Julia callback function. The definition of this function is showed bel…

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## [Indexing DataFrame with : does not generate a copy](https://discourse.julialang.org/t/indexing-dataframe-with-does-not-generate-a-copy/78002)

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**Author:** [@wsshin](https://discourse.julialang.org/u/wsshin)\
**Replies:** 2\
**Last updated:** [March 17, 2022, 6:16am UTC](https://discourse.julialang.org/t/indexing-dataframe-with-does-not-generate-a-copy/78002 "2022-03-17T06:16:04Z")

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The DataFrames.jl documentation says Since df\[!, :col\] does not make a copy, changing the elements of the column vector returned by this syntax will affect the values stored in the original df . To get a copy of the co…

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## [Why is this numerical scheme so much faster when using \`collect()\` than a for loop?](https://discourse.julialang.org/t/why-is-this-numerical-scheme-so-much-faster-when-using-collect-than-a-for-loop/77949)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 4\
**Last updated:** [March 17, 2022, 2:34am UTC](https://discourse.julialang.org/t/why-is-this-numerical-scheme-so-much-faster-when-using-collect-than-a-for-loop/77949 "2022-03-17T02:34:38Z")

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Consider a toy algorithm that finds the maximum of a vector, then removes it and alters the other entries of the vector in a way that depends on whether they are located at a lower or higher index. In the code below, wh…

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## [JET.jl reports error for every \`println\`](https://discourse.julialang.org/t/jet-jl-reports-error-for-every-println/77991)

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**Author:** [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Replies:** 2\
**Last updated:** [March 17, 2022, 12:30am UTC](https://discourse.julialang.org/t/jet-jl-reports-error-for-every-println/77991 "2022-03-17T00:30:21Z")

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JET.jl reports run-time dispatch errors for every println, even if the println line in question is not reached. Is that desired? (it makes harder to check for errors in any package that prints information optionally for …

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## [How to get system state during event handling?](https://discourse.julialang.org/t/how-to-get-system-state-during-event-handling/77994)

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**Author:** [@egor](https://discourse.julialang.org/u/egor)\
**Replies:** 1\
**Last updated:** [March 16, 2022, 10:17pm UTC](https://discourse.julialang.org/t/how-to-get-system-state-during-event-handling/77994 "2022-03-16T22:17:17Z")

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Hello everyone, I’m going through an example from the documentation about event handling during dynamic system integration. using DifferentialEquations function f(du,u,p,t) du\[1\] = -u\[1\] end u0 = \[10.0\] const V = 1 …

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## [Condition to use or not to use threaded for loop](https://discourse.julialang.org/t/condition-to-use-or-not-to-use-threaded-for-loop/77935)

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**Author:** [@JesperMartinsson](https://discourse.julialang.org/u/JesperMartinsson)\
**Replies:** 4\
**Last updated:** [March 16, 2022, 10:04pm UTC](https://discourse.julialang.org/t/condition-to-use-or-not-to-use-threaded-for-loop/77935 "2022-03-16T22:04:57Z")

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I have a function with a for-loop that I like to turn multi- or single-threaded by a separate argument. For example: function foo(cond) if cond @inbounds Threads.@threads for n = 1:N # computatio…

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## [Using alternative array container types in JuMP](https://discourse.julialang.org/t/using-alternative-array-container-types-in-jump/77707)

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**Author:** [@BSnelling](https://discourse.julialang.org/u/BSnelling)\
**Replies:** 5\
**Last updated:** [March 16, 2022, 8:03pm UTC](https://discourse.julialang.org/t/using-alternative-array-container-types-in-jump/77707 "2022-03-16T20:03:04Z")

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I am trying to force the container type used by a JuMP model. My example uses KeyedArray but I’ve seen a similar error when specifying other types from outside JuMP (e.g. AxisArray). using JuMP, AxisKeys, GLPK vals = \[…

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## [Very large arrays](https://discourse.julialang.org/t/very-large-arrays/77942)

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**Author:** [@Lilith](https://discourse.julialang.org/u/Lilith)\
**Replies:** 5\
**Last updated:** [March 16, 2022, 5:18pm UTC](https://discourse.julialang.org/t/very-large-arrays/77942 "2022-03-16T17:18:51Z")

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Does Julia support AbstractArrays larger than typemax(Int)? (e.g. sparse arrays or arrays larger than 2^31 on a 32-bit Julia install) Is code in Base allowed to assume that an AbstractArray has length no more than typem…

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## [\`unique(Vector{CustomStruct})\` requires method for hash | Bug or misleading documentation?](https://discourse.julialang.org/t/unique-vector-customstruct-requires-method-for-hash-bug-or-misleading-documentation/77974)

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**Author:** [@aaronpeikert](https://discourse.julialang.org/u/aaronpeikert)\
**Replies:** 6\
**Last updated:** [March 16, 2022, 5:02pm UTC](https://discourse.julialang.org/t/unique-vector-customstruct-requires-method-for-hash-bug-or-misleading-documentation/77974 "2022-03-16T17:02:02Z")

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I was surprised to see that it is not enough to implement isequal to get unique for free, though the documentation seems to suggest it: https://docs.julialang.org/en/v1/base/collections/#Base.unique Return an array co…

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## [How to convert CartesianIndex{N} values to Int64](https://discourse.julialang.org/t/how-to-convert-cartesianindex-n-values-to-int64/15074)

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**Author:** [@Tomoyuki\_Kosaka](https://discourse.julialang.org/u/Tomoyuki_Kosaka)\
**Replies:** 18\
**Last updated:** [March 16, 2022, 4:13pm UTC](https://discourse.julialang.org/t/how-to-convert-cartesianindex-n-values-to-int64/15074 "2022-03-16T16:13:36Z")

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I’m using Clustering Pkg and function fuzzy\_cmean, and try to assign the cluster number to each data. If I use findmax(FuzzyCMeansResult.weights, dims=2) will give us (value, CartesianIndex(2)). Then, I cannot find out…

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## [CxxWrap.jl, why these code report error?](https://discourse.julialang.org/t/cxxwrap-jl-why-these-code-report-error/77984)

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**Author:** [@Brian1](https://discourse.julialang.org/u/Brian1)\
**Replies:** 0\
**Last updated:** [March 16, 2022, 4:11pm UTC](https://discourse.julialang.org/t/cxxwrap-jl-why-these-code-report-error/77984 "2022-03-16T16:11:01Z")

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I’m using CxxWrap. My setup: Julia: 1.7.2 CxxWrap: 0.12.0 when I do this, there come error: the error: the dependency is Can anyone can tell me why this error happened?

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## [Destructuring object into DataFrame](https://discourse.julialang.org/t/destructuring-object-into-dataframe/77964)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 6\
**Last updated:** [March 16, 2022, 3:44pm UTC](https://discourse.julialang.org/t/destructuring-object-into-dataframe/77964 "2022-03-16T15:44:20Z")

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Hi all, I have an array of objects that I would like to convert to a DataFrame. Each object has some arrays and some individual values. I would like to destructure the arrays into individual rows and columns and repeat …

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## [Juniper integer-objective fails on specific parameters](https://discourse.julialang.org/t/juniper-integer-objective-fails-on-specific-parameters/77940)

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**Author:** [@ecyrb](https://discourse.julialang.org/u/ecyrb)\
**Replies:** 6\
**Last updated:** [March 16, 2022, 3:09pm UTC](https://discourse.julialang.org/t/juniper-integer-objective-fails-on-specific-parameters/77940 "2022-03-16T15:09:50Z")

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Simple sum-of-squares toy example, succeeds with 5 variables, stack-trace with 6 variables. I know it’s sort of a silly example, but it feels to me like the behaviour should be consistent between problem\_size = 5 and 6.…

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## [Why does my hash function return a different value to the built in hash function?](https://discourse.julialang.org/t/why-does-my-hash-function-return-a-different-value-to-the-built-in-hash-function/77973)

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**Author:** [@Jon\_Barker](https://discourse.julialang.org/u/Jon_Barker)\
**Replies:** 7\
**Last updated:** [March 16, 2022, 2:33pm UTC](https://discourse.julialang.org/t/why-does-my-hash-function-return-a-different-value-to-the-built-in-hash-function/77973 "2022-03-16T14:33:41Z")

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I copied the hash function code from here: And ran it under J1.7 but I get different results. Why?

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## [Some registries failed to update!?](https://discourse.julialang.org/t/some-registries-failed-to-update/77969)

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**Author:** [@HerAdri](https://discourse.julialang.org/u/HerAdri)\
**Replies:** 0\
**Last updated:** [March 16, 2022, 1:08pm UTC](https://discourse.julialang.org/t/some-registries-failed-to-update/77969 "2022-03-16T13:08:17Z")

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When performing the command (@v1.7) pkg\>up, I receive the following alert: Error: Some registries failed to update: from the following list: (@v1.7) pkg\> st Status C:\\Users\\Hermesr\\.julia\\environments\\v1.7\\Project.to…

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## [Assigning a color to each variable](https://discourse.julialang.org/t/assigning-a-color-to-each-variable/77967)

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**Author:** [@Juan\_Mac\_Donagh](https://discourse.julialang.org/u/Juan_Mac_Donagh)\
**Replies:** 0\
**Last updated:** [March 16, 2022, 12:56pm UTC](https://discourse.julialang.org/t/assigning-a-color-to-each-variable/77967 "2022-03-16T12:56:06Z")

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Hi, I was wondering if there was a way of automatically assigning a color to each bar when doing a bar plot (Plots.bar), something similar to color=:variable in Gadfly. My data looks like this: Var1 Var2 Var3 1 …

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## [Method Error : Not identifying Integer as Any](https://discourse.julialang.org/t/method-error-not-identifying-integer-as-any/77957)

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**Author:** [@imantha](https://discourse.julialang.org/u/imantha)\
**Replies:** 3\
**Last updated:** [March 16, 2022, 12:39pm UTC](https://discourse.julialang.org/t/method-error-not-identifying-integer-as-any/77957 "2022-03-16T12:39:01Z")

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Hi, I have function update\_agent\_attributes that accepts a Dict{Symbol, Any} as one of the arguments. However when I pass a Dict{Symbol, Interger} I get an Method Error. Any idea why ? mutable struct Casualty id :: …

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## [Unzip function](https://discourse.julialang.org/t/unzip-function/77959)

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**Author:** [@Cevheriferd](https://discourse.julialang.org/u/Cevheriferd)\
**Replies:** 2\
**Last updated:** [March 16, 2022, 12:14pm UTC](https://discourse.julialang.org/t/unzip-function/77959 "2022-03-16T12:14:51Z")

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Basically addressing the issue here. Is there a reason this function has not been implemented yet?

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## [Define mul! for DiffEqArrayOperator](https://discourse.julialang.org/t/define-mul-for-diffeqarrayoperator/77911)

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**Author:** [@Elyco](https://discourse.julialang.org/u/Elyco)\
**Replies:** 4\
**Last updated:** [March 16, 2022, 11:27am UTC](https://discourse.julialang.org/t/define-mul-for-diffeqarrayoperator/77911 "2022-03-16T11:27:17Z")

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Hi, I’m trying to use the SplitODEProblem interface in order to improve the performance of my differential equation solver. The problem has a linear part which can sum into matrix multiplication, and a non linear part. …

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## [Is any way to print DataFrames using heat maps as background?](https://discourse.julialang.org/t/is-any-way-to-print-dataframes-using-heat-maps-as-background/77744)

<div class="topic-metadata">

**Author:** [@Dan\_Micsa](https://discourse.julialang.org/u/Dan_Micsa)\
**Replies:** 45\
**Last updated:** [March 16, 2022, 9:16am UTC](https://discourse.julialang.org/t/is-any-way-to-print-dataframes-using-heat-maps-as-background/77744 "2022-03-16T09:16:44Z")

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I want to print in various notebooks dataframes setting the background of each cell. This is possible in Python. Here is an example using a heatmap. Something that looks like: Is some library or code out there to do …

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## [Calculate specificity (true negative rate) in crossvalidation in AutoMLPipeline](https://discourse.julialang.org/t/calculate-specificity-true-negative-rate-in-crossvalidation-in-automlpipeline/77958)

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**Author:** [@Michele\_Avanzo](https://discourse.julialang.org/u/Michele_Avanzo)\
**Replies:** 0\
**Last updated:** [March 16, 2022, 10:21am UTC](https://discourse.julialang.org/t/calculate-specificity-true-negative-rate-in-crossvalidation-in-automlpipeline/77958 "2022-03-16T10:21:08Z")

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Hi all, I am used to calculate sensitivity and specificity in classification problems. Sensitivity is recall, so not a problem, but specificity (true negative) is usually not included in evaluation metrics. Is it possi…

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