# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1839

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

**Page:** 1840

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## [Surprising result if type annotations are used](https://discourse.julialang.org/t/surprising-result-if-type-annotations-are-used/33685)

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**Author:** [@ranocha](https://discourse.julialang.org/u/ranocha)\
**Replies:** 2\
**Last updated:** [January 24, 2020, 9:17am UTC](https://discourse.julialang.org/t/surprising-result-if-type-annotations-are-used/33685 "2020-01-24T09:17:45Z")

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Consider the following code: julia\> function foo(T) if T == Float64 v::Vector{Float64} = zeros(5) else v = T\[1, 2, 3, 4, 5\] end v end jul…

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## [Confusion with local packages](https://discourse.julialang.org/t/confusion-with-local-packages/33714)

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**Author:** [@jebej](https://discourse.julialang.org/u/jebej)\
**Replies:** 3\
**Last updated:** [January 24, 2020, 9:16am UTC](https://discourse.julialang.org/t/confusion-with-local-packages/33714 "2020-01-24T09:16:44Z")

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Back in the 0.6 days, I used to push! to LOAD\_PATH a directory containing all the packages I worked on. After updating to 1.0, I kept using the same strategy, which meant adding all the packages that my packages depended…

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## [Question on behavior with comparisons in MonteCarloMeasurements](https://discourse.julialang.org/t/question-on-behavior-with-comparisons-in-montecarlomeasurements/33679)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 7\
**Last updated:** [January 24, 2020, 8:54am UTC](https://discourse.julialang.org/t/question-on-behavior-with-comparisons-in-montecarlomeasurements/33679 "2020-01-24T08:54:35Z")

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I’m playing with MonteCarloMeasurements but running up against limitations around comparisons. julia\> a = Particles(1000, Uniform(0.0,10.0)) Part1000(5.0 ± 2.89) julia\> b = Particles(1000, Uniform(0.0, 10.0)) Part1000(…

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## [Proposal: syntax for accessing arrays using relative indices](https://discourse.julialang.org/t/proposal-syntax-for-accessing-arrays-using-relative-indices/33699)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 11\
**Last updated:** [January 24, 2020, 1:00am UTC](https://discourse.julialang.org/t/proposal-syntax-for-accessing-arrays-using-relative-indices/33699 "2020-01-24T01:00:35Z")

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Hi! Let’s say I want to access 4 elements of an array. Today, I do something like: data\[1200:1203\] data\[1200:1200+3\] or data\[i:i+3\] Wouldn’t be nice if we have a syntax to access elements using relative indices? Som…

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## [Computation of elliptic integrals with arbitrary precision](https://discourse.julialang.org/t/computation-of-elliptic-integrals-with-arbitrary-precision/33717)

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**Author:** [@Gregstrq](https://discourse.julialang.org/u/Gregstrq)\
**Replies:** 1\
**Last updated:** [January 24, 2020, 12:38am UTC](https://discourse.julialang.org/t/computation-of-elliptic-integrals-with-arbitrary-precision/33717 "2020-01-24T00:38:39Z")

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I have seen the issue Support for extended precision in Elliptic.jl. It references the pull request Jacobi elliptic functions and complete elliptic integral of the first kind in SpecialFunctions.jl which is year old and …

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## [Why "Threads.@threads for " doesn't use all possible threads?](https://discourse.julialang.org/t/why-threads-threads-for-doesnt-use-all-possible-threads/33711)

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**Author:** [@BMval](https://discourse.julialang.org/u/BMval)\
**Replies:** 6\
**Last updated:** [January 23, 2020, 9:38pm UTC](https://discourse.julialang.org/t/why-threads-threads-for-doesnt-use-all-possible-threads/33711 "2020-01-23T21:38:26Z")

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Good day. I have 12 cores. So nthread() gives 12. when I used "Threads.@threads for ", only 8 thread was created. RAM memory was utilized for up to 85%. Can memory limitations and the number of thread created be conn…

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## [Type instability in closure after reassigning a variable](https://discourse.julialang.org/t/type-instability-in-closure-after-reassigning-a-variable/33656)

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**Author:** [@Skoffer](https://discourse.julialang.org/u/Skoffer)\
**Replies:** 7\
**Last updated:** [January 23, 2020, 8:35pm UTC](https://discourse.julialang.org/t/type-instability-in-closure-after-reassigning-a-variable/33656 "2020-01-23T20:35:09Z")

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I’ve stumbled recently on this behavior (julia 1.3.1): function test() s = "hello" s = lowercase(s) x() = s x() end and @code\_warntype test() yields Variables #self#::Core.Compiler.Const(test, false)…

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## [BSON confusing behaviour](https://discourse.julialang.org/t/bson-confusing-behaviour/33700)

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**Author:** [@compleat](https://discourse.julialang.org/u/compleat)\
**Replies:** 2\
**Last updated:** [January 23, 2020, 1:29pm UTC](https://discourse.julialang.org/t/bson-confusing-behaviour/33700 "2020-01-23T13:29:58Z")

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Apologies for so many questions in so short a time, but I have decided to do a “push”, so I am tackling the issues in sequence (and there are alot of them). Regarding using BSON to load: Here is an example of trying to…

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## [Gentler transformation from real to positive](https://discourse.julialang.org/t/gentler-transformation-from-real-to-positive/33695)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 15\
**Last updated:** [January 23, 2020, 7:54pm UTC](https://discourse.julialang.org/t/gentler-transformation-from-real-to-positive/33695 "2020-01-23T19:54:59Z")

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I am solving an equilibrium of an economic model for prices p \> 0. I need to do this robustly for “wacky” parameter values when I am fitting the model to the data in an outer loop. I have coded up a market clearing resi…

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## [Too much time taken to build GR](https://discourse.julialang.org/t/too-much-time-taken-to-build-gr/22798)

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**Author:** [@Ajaychat3](https://discourse.julialang.org/u/Ajaychat3)\
**Replies:** 5\
**Last updated:** [January 23, 2020, 6:55pm UTC](https://discourse.julialang.org/t/too-much-time-taken-to-build-gr/22798 "2020-01-23T18:55:53Z")

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I am using julia 1.1.0 on win 10 and it takes long time to build GR. It was taking long time and so I disconnected from internet and it resulted in error. It seems to download couple of file during build process which I …

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## [Has anyone used OpenTeams?](https://discourse.julialang.org/t/has-anyone-used-openteams/33697)

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**Author:** [@ven-k](https://discourse.julialang.org/u/ven-k)\
**Replies:** 0\
**Last updated:** [January 23, 2020, 11:32am UTC](https://discourse.julialang.org/t/has-anyone-used-openteams/33697 "2020-01-23T11:32:33Z")

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I came across OpenTeams, which describes itself as LinkedIn for OSS. I saw NumFOCUS, Quantecon, even Julia( but without the whole community). Could I get some advice if it’s a good platform to log on? and if any of you …

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## [Atan(y,x) for complex numbers](https://discourse.julialang.org/t/atan-y-x-for-complex-numbers/33692)

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**Author:** [@arturgower](https://discourse.julialang.org/u/arturgower)\
**Replies:** 4\
**Last updated:** [January 23, 2020, 5:15pm UTC](https://discourse.julialang.org/t/atan-y-x-for-complex-numbers/33692 "2020-01-23T17:15:49Z")

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There doesn’t seem to be an implementation for atan when x and y are complex numbers. The currently implement atan(y/x) is not a replacement, as it loses the information on which quadrants x and y are in. This is import…

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## [Find in in Julai 1.0 .. LinearIndices to long](https://discourse.julialang.org/t/find-in-in-julai-1-0-linearindices-to-long/33674)

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**Author:** [@programista](https://discourse.julialang.org/u/programista)\
**Replies:** 3\
**Last updated:** [January 23, 2020, 3:57pm UTC](https://discourse.julialang.org/t/find-in-in-julai-1-0-linearindices-to-long/33674 "2020-01-23T15:57:49Z")

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in vector los i need to find some ones new code of julai is some comlicated : (LinearIndices(los.==1))\[findall(los.==1)\] Is some more easy to do ? Paul

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## [Color scale for an ordered variable](https://discourse.julialang.org/t/color-scale-for-an-ordered-variable/33702)

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**Author:** [@yanivab](https://discourse.julialang.org/u/yanivab)\
**Replies:** 0\
**Last updated:** [January 23, 2020, 3:22pm UTC](https://discourse.julialang.org/t/color-scale-for-an-ordered-variable/33702 "2020-01-23T15:22:50Z")

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I’m trying to make a scatter plot with marker color denoting the data session collection number. How does one do this? If I set group = :session, I get non sequential colours (even with, say, color\_palette = :blues): @…

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## [\[ANN\] Onda.jl: A format for multi-sensor, multi-channel, LPCM-encodable recordings](https://discourse.julialang.org/t/ann-onda-jl-a-format-for-multi-sensor-multi-channel-lpcm-encodable-recordings/32650)

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**Author:** [@jrevels](https://discourse.julialang.org/u/jrevels)\
**Replies:** 12\
**Last updated:** [January 23, 2020, 1:00pm UTC](https://discourse.julialang.org/t/ann-onda-jl-a-format-for-multi-sensor-multi-channel-lpcm-encodable-recordings/32650 "2020-01-23T13:00:17Z")

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Hello! I’m pleased to announce Beacon Biosignal’s impending open-source release of both Onda.jl and the Onda format. Onda is a lightweight format for storing and manipulating datasets of multi-sensor, multi-channel, LPC…

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## [Parsing of functions really slow](https://discourse.julialang.org/t/parsing-of-functions-really-slow/33626)

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**Author:** [@IljaK91](https://discourse.julialang.org/u/IljaK91)\
**Replies:** 7\
**Last updated:** [January 23, 2020, 10:24am UTC](https://discourse.julialang.org/t/parsing-of-functions-really-slow/33626 "2020-01-23T10:24:10Z")

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Hey everyone, In VSCode, when I select a function definition and press STRG + Enter, it takes really long until it fully hits the REPL. It starts flickering in the console and just strange in total. Does anyone else ha…

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## [Đ (Edh) - maybe a competitor, or can it make friends with Julia?](https://discourse.julialang.org/t/d-edh-maybe-a-competitor-or-can-it-make-friends-with-julia/33539)

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**Author:** [@complyue](https://discourse.julialang.org/u/complyue)\
**Replies:** 9\
**Last updated:** [January 23, 2020, 8:31am UTC](https://discourse.julialang.org/t/d-edh-maybe-a-competitor-or-can-it-make-friends-with-julia/33539 "2020-01-23T08:31:39Z")

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I’m author of Đ (Edh), just released it to public. I have long been watching on Julia (since 0.4.x I roughly remember), I’m sincerely happy to see it reaches 1.3 nowadays! But I regret to have had no enough materials ga…

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## [A data scientist's thoughts on R & Python](https://discourse.julialang.org/t/a-data-scientists-thoughts-on-r-python/33402)

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**Author:** [@Gunter\_Faes](https://discourse.julialang.org/u/Gunter_Faes)\
**Replies:** 17\
**Last updated:** [January 23, 2020, 8:26am UTC](https://discourse.julialang.org/t/a-data-scientists-thoughts-on-r-python/33402 "2020-01-23T08:26:54Z")

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This block by Gordon Shotwell describes his comparative thoughts on R and Python. Maybe this article is helpful to understand how the “ordinary” data scientist thinks and what he needs in his daily work? And helps to des…

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## [Example C vs Julia vs Python](https://discourse.julialang.org/t/example-c-vs-julia-vs-python/33120)

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**Author:** [@jleman](https://discourse.julialang.org/u/jleman)\
**Replies:** 41\
**Last updated:** [January 23, 2020, 6:44am UTC](https://discourse.julialang.org/t/example-c-vs-julia-vs-python/33120 "2020-01-23T06:44:52Z")

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I have been using Julia for about a year. I am an EE, not a programmer. In one of my graduate EE courses I requested to use Julia instead of C for an assignment and got the task of comparing performance of C, Julia, an…

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## [Timings for different groupby approaches](https://discourse.julialang.org/t/timings-for-different-groupby-approaches/33680)

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**Author:** [@venuur](https://discourse.julialang.org/u/venuur)\
**Replies:** 2\
**Last updated:** [January 23, 2020, 2:05am UTC](https://discourse.julialang.org/t/timings-for-different-groupby-approaches/33680 "2020-01-23T02:05:18Z")

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I am running some simulations at work, and I wanted to experiment with different approaches for performing a groupby and then running the simulation. The idea is to run a simulation of each group (identified by an id col…

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## [\[ANN\] More flexible & user-friendly profile visualization (ProfileView 0.6)](https://discourse.julialang.org/t/ann-more-flexible-user-friendly-profile-visualization-profileview-0-6/33648)

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**Author:** [@tim.holy](https://discourse.julialang.org/u/tim.holy)\
**Replies:** 8\
**Last updated:** [January 22, 2020, 11:32pm UTC](https://discourse.julialang.org/t/ann-more-flexible-user-friendly-profile-visualization-profileview-0-6/33648 "2020-01-22T23:32:31Z")

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I’ve recently completed a major rewrite of ProfileView.jl, a package for visualizing profiling data as a tool for understanding performance bottlenecks. ProfileView was written back in the Julia 0.1 days (yes, back in 20…

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## [Custom images on Juliabox](https://discourse.julialang.org/t/custom-images-on-juliabox/33678)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 0\
**Last updated:** [January 22, 2020, 10:40pm UTC](https://discourse.julialang.org/t/custom-images-on-juliabox/33678 "2020-01-22T22:40:32Z")

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I see in the list of features that Juliabox supports custom images, but I can’t find any documentation on it. I wanted to understand if it can build some packages into the base image before I commit $14/mth to test it o…

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## [TensorFlow \`matmul\` equivalent in Julia: matrix multiplication with two given tensor dimensions](https://discourse.julialang.org/t/tensorflow-matmul-equivalent-in-julia-matrix-multiplication-with-two-given-tensor-dimensions/33676)

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**Author:** [@tanhevg](https://discourse.julialang.org/u/tanhevg)\
**Replies:** 5\
**Last updated:** [January 22, 2020, 10:14pm UTC](https://discourse.julialang.org/t/tensorflow-matmul-equivalent-in-julia-matrix-multiplication-with-two-given-tensor-dimensions/33676 "2020-01-22T22:14:09Z")

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Does Julia have an equivalent of TensorFlow matmul ? I need matrix multiplication using two given (or pre-defined) dimensions of the tensors, preserving other dimensions. Tensorflow matmul uses the two innermost tensor …

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## [Threads memory allocations](https://discourse.julialang.org/t/threads-memory-allocations/33675)

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**Author:** [@squirrel](https://discourse.julialang.org/u/squirrel)\
**Replies:** 2\
**Last updated:** [January 22, 2020, 9:03pm UTC](https://discourse.julialang.org/t/threads-memory-allocations/33675 "2020-01-22T21:03:43Z")

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Hi. I’m really trying to understand parallel programming in Julia. Can someone please explain to me why using threads requires so many memory allocations? using BenchmarkTools using .Threads function test\_serial(u) …

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## [Interpolation-weighted quadrature rules](https://discourse.julialang.org/t/interpolation-weighted-quadrature-rules/32170)

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**Author:** [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Replies:** 1\
**Last updated:** [January 22, 2020, 8:56pm UTC](https://discourse.julialang.org/t/interpolation-weighted-quadrature-rules/32170 "2020-01-22T20:56:07Z")

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Some of you might be interested in the following notebook, which shows how to construct optimal Gaussian quadrature schemes for arbitrary weight functions constructed from interpolated data: Notes on Solar-Weighted Gau…

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## [Performance bug when creating a sparse matrix via Python](https://discourse.julialang.org/t/performance-bug-when-creating-a-sparse-matrix-via-python/33661)

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**Author:** [@TomDeWeer](https://discourse.julialang.org/u/TomDeWeer)\
**Replies:** 3\
**Last updated:** [January 22, 2020, 7:05pm UTC](https://discourse.julialang.org/t/performance-bug-when-creating-a-sparse-matrix-via-python/33661 "2020-01-22T19:05:22Z")

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Hi all, I am trying to solve Ax=B for a sparse A in Julia. I create the A and B matrix in Python and import it into Julia via the PyCall package.The problem is that this import takes ages and consumes all my RAM. I beli…

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## [COM server for editing Excel files?](https://discourse.julialang.org/t/com-server-for-editing-excel-files/33672)

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**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 0\
**Last updated:** [January 22, 2020, 7:10pm UTC](https://discourse.julialang.org/t/com-server-for-editing-excel-files/33672 "2020-01-22T19:10:54Z")

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I’m using GitHub - felipenoris/XLSX.jl: Excel file reader and writer for the Julia language. to write data into Excel files and it works great!Thanks,@felipenoris! I would also like to add some formatting(colors, borders…

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## [Can I avoid field struct declaration?](https://discourse.julialang.org/t/can-i-avoid-field-struct-declaration/33671)

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**Author:** [@Noel\_Araujo](https://discourse.julialang.org/u/Noel_Araujo)\
**Replies:** 5\
**Last updated:** [January 22, 2020, 6:45pm UTC](https://discourse.julialang.org/t/can-i-avoid-field-struct-declaration/33671 "2020-01-22T18:45:31Z")

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I don’t know how to search this topic, then I prefer to ask. If I did not misunderstood, the Constructor only works when all the field are supplied. I was wandering if I could define a struct and some of the fields will…

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## [Interpolated heatmap with contour line in VegaLite.jl](https://discourse.julialang.org/t/interpolated-heatmap-with-contour-line-in-vegalite-jl/33559)

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**Author:** [@affans](https://discourse.julialang.org/u/affans)\
**Replies:** 1\
**Last updated:** [January 22, 2020, 5:48pm UTC](https://discourse.julialang.org/t/interpolated-heatmap-with-contour-line-in-vegalite-jl/33559 "2020-01-22T17:48:38Z")

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Looking to generate a continous heatmap of data, with a contour line, something line the following plot: Example data if someone wants to play with it: delay,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,7…

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## [Help to create a structure to use ForwardDiff package](https://discourse.julialang.org/t/help-to-create-a-structure-to-use-forwarddiff-package/33657)

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**Author:** [@Ronis\_BR](https://discourse.julialang.org/u/Ronis_BR)\
**Replies:** 5\
**Last updated:** [January 22, 2020, 5:50pm UTC](https://discourse.julialang.org/t/help-to-create-a-structure-to-use-forwarddiff-package/33657 "2020-01-22T17:50:33Z")

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Hi! I want to use the ForwardDiff package to perform automatic differentiation of a function. However, this function requires an structure in which I am declaring like this: @with\_kw mutable struct MyStruct{T\<:Real} …

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