# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=443

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**Page:** 444

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## [JuMP conditional constraint](https://discourse.julialang.org/t/jump-conditional-constraint/40575)

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**Author:** [@m.lavaiyan](https://discourse.julialang.org/u/m.lavaiyan)\
**Replies:** 9\
**Last updated:** [June 2, 2020, 2:21pm UTC](https://discourse.julialang.org/t/jump-conditional-constraint/40575 "2020-06-02T14:21:28Z")

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I want to implement a conditional constraint to my model where each non-zero variable, force the next two variables to be zero. In other words, if x\[t\]=0 then x\[t+1\]=0 and x\[t+2\]=0. I tried a quadratic constrain as belo…

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## [The test isequal(+0.0,-0.0) returns FALSE](https://discourse.julialang.org/t/the-test-isequal-0-0-0-0-returns-false/38404)

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**Author:** [@Lian\_Yunlong](https://discourse.julialang.org/u/Lian_Yunlong)\
**Replies:** 16\
**Last updated:** [June 2, 2020, 7:31am UTC](https://discourse.julialang.org/t/the-test-isequal-0-0-0-0-returns-false/38404 "2020-06-02T07:31:09Z")

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so as isequal(+0.0im,-0.0im). I discovered this during a painful debug process. I really want to understand the philosophy behind this designing, and I wish to get some advice on numerical stability. Thank you @everyon…

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## [Sample rate conversion from audio files](https://discourse.julialang.org/t/sample-rate-conversion-from-audio-files/40578)

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**Author:** [@bafonso](https://discourse.julialang.org/u/bafonso)\
**Replies:** 3\
**Last updated:** [June 2, 2020, 7:25am UTC](https://discourse.julialang.org/t/sample-rate-conversion-from-audio-files/40578 "2020-06-02T07:25:04Z")

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What is the easiest way to load and convert audio files? I’d rather do it on the fly instead of loading and saving as a batch. Right now I am loading files with load or loadstreaming but I need to have a uniform sampling…

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## [\[DataFrames Question\]: Transpose of dataframe](https://discourse.julialang.org/t/dataframes-question-transpose-of-dataframe/28524)

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**Author:** [@Patrick\_Mineault](https://discourse.julialang.org/u/Patrick_Mineault)\
**Replies:** 2\
**Last updated:** [June 2, 2020, 2:41am UTC](https://discourse.julialang.org/t/dataframes-question-transpose-of-dataframe/28524 "2020-06-02T02:41:27Z")

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Question: How do I transpose a dataframe (columns become rows, rows become columns)?

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## [How do I use multithreaded BLAS in each MPI process](https://discourse.julialang.org/t/how-do-i-use-multithreaded-blas-in-each-mpi-process/40587)

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**Author:** [@shipengcheng1230](https://discourse.julialang.org/u/shipengcheng1230)\
**Replies:** 0\
**Last updated:** [June 1, 2020, 10:38pm UTC](https://discourse.julialang.org/t/how-do-i-use-multithreaded-blas-in-each-mpi-process/40587 "2020-06-01T22:38:25Z")

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I would like to launch one MPI process on each node and perform multithreaded BLAS, the same as tested here, and discussed at combining-distributed-computing-multithreading. Specifically, I am trying to use Elemental.jl:…

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## [Performance of lp\_rhs\_perturbation\_range](https://discourse.julialang.org/t/performance-of-lp-rhs-perturbation-range/40551)

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**Author:** [@gleyland](https://discourse.julialang.org/u/gleyland)\
**Replies:** 4\
**Last updated:** [June 1, 2020, 10:01pm UTC](https://discourse.julialang.org/t/performance-of-lp-rhs-perturbation-range/40551 "2020-06-01T22:01:13Z")

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Hi, I have a JuMP model (an LP, currently solved with GLPK) for which I query shadow prices and perturbation ranges of a number of (a few thousand in a large-ish problem) constraints. Solving the LP takes a couple of s…

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## [How to parallerize dual coordinet descent mehods on GPU using CUDA.jl?](https://discourse.julialang.org/t/how-to-parallerize-dual-coordinet-descent-mehods-on-gpu-using-cuda-jl/40344)

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**Author:** [@msekino](https://discourse.julialang.org/u/msekino)\
**Replies:** 11\
**Last updated:** [June 1, 2020, 2:11pm UTC](https://discourse.julialang.org/t/how-to-parallerize-dual-coordinet-descent-mehods-on-gpu-using-cuda-jl/40344 "2020-06-01T14:11:43Z")

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Now I want to parallerize something like the following dual coordinate descent method. I’m trying to use CUDA.jl, however I’m stuck for days… # X = (x\[1\], ..., x\[numvec\]) numvec = 500000 lenvec = 50000 xs = \[sprandn(le…

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## [Visualize discontinuous Galerkin](https://discourse.julialang.org/t/visualize-discontinuous-galerkin/40522)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 0\
**Last updated:** [May 31, 2020, 10:09pm UTC](https://discourse.julialang.org/t/visualize-discontinuous-galerkin/40522 "2020-05-31T22:09:00Z")

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Is there any existing convenient method to visualize the results of discontinuous Galerkin finite element data? Would prefer something similar to Makie’s mesh method, but other packages are fine also.

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## [Large-Scale HPC Project on Probabilistic Programming at Scale in Conjunction with Scientific Simulators](https://discourse.julialang.org/t/large-scale-hpc-project-on-probabilistic-programming-at-scale-in-conjunction-with-scientific-simulators/39416)

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**Author:** [@ludgerpaehler](https://discourse.julialang.org/u/ludgerpaehler)\
**Replies:** 8\
**Last updated:** [May 31, 2020, 7:41pm UTC](https://discourse.julialang.org/t/large-scale-hpc-project-on-probabilistic-programming-at-scale-in-conjunction-with-scientific-simulators/39416 "2020-05-31T19:41:23Z")

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Hi everyone, we recently got approval for our 250m CPU-hour GCS supercomputing project named “Bayesian Inference of the Reactive Shock-Bubble Interaction - Probabilistic Programming at Scale”. A rough sketch: The Baye…

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## [Solve a SDE using Neural network](https://discourse.julialang.org/t/solve-a-sde-using-neural-network/40177)

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**Author:** [@shoudao](https://discourse.julialang.org/u/shoudao)\
**Replies:** 11\
**Last updated:** [May 31, 2020, 3:30pm UTC](https://discourse.julialang.org/t/solve-a-sde-using-neural-network/40177 "2020-05-31T15:30:32Z")

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I am trying to solve SDE using Neural networks recently. I have an idea to solve a SDE in this form: d X\_{t}=f\\left(X\_{t}, t,r,\\mu\_t \\right) d t+g\\left(X\_{t}, t,r,\\mu\_t \\right) d W\_{t} But I am not sure how to impleme…

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## [Random graphs, fully-connected graphs](https://discourse.julialang.org/t/random-graphs-fully-connected-graphs/40445)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 17\
**Last updated:** [May 31, 2020, 2:47pm UTC](https://discourse.julialang.org/t/random-graphs-fully-connected-graphs/40445 "2020-05-31T14:47:00Z")

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Hi, How does one create a fully connected graph with LightGraphs.jl? I looked at the documentation and did not see an obvious function. A second equation is how to create a random graph with p percent of the edges? I …

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## [3D array reshape error](https://discourse.julialang.org/t/3d-array-reshape-error/40507)

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**Author:** [@dialektike](https://discourse.julialang.org/u/dialektike)\
**Replies:** 2\
**Last updated:** [May 31, 2020, 2:22pm UTC](https://discourse.julialang.org/t/3d-array-reshape-error/40507 "2020-05-31T14:22:20Z")

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A = np.array(range(1, 9)).reshape(2, 2, 2) # swap 2nd and 3rd axes: A.transpose((0, 2, 1)) I’m also trying to julia like the above python code. trying like this… A = reshape(1:8, 2, 2, 2) # swap 2nd and 3rd axes: re…

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## [Parameter substitutions in ModelingToolkit.jl](https://discourse.julialang.org/t/parameter-substitutions-in-modelingtoolkit-jl/34527)

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**Author:** [@DR59](https://discourse.julialang.org/u/DR59)\
**Replies:** 8\
**Last updated:** [May 30, 2020, 7:18am UTC](https://discourse.julialang.org/t/parameter-substitutions-in-modelingtoolkit-jl/34527 "2020-05-30T07:18:57Z")

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Hi, I’m getting to grips with ModelingToolkit.jl. Let’s take the ODE building example in the tutorial: @parameters t σ ρ β @variables x(t) y(t) z(t) @derivatives D'~t eqs = \[D(x) ~ σ\*(y-x), D(y) ~ x\*(ρ-z)-y, …

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## [Optimization with cost and constraints returned from a single function call](https://discourse.julialang.org/t/optimization-with-cost-and-constraints-returned-from-a-single-function-call/40433)

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**Author:** [@DrPapa](https://discourse.julialang.org/u/DrPapa)\
**Replies:** 4\
**Last updated:** [May 29, 2020, 11:28pm UTC](https://discourse.julialang.org/t/optimization-with-cost-and-constraints-returned-from-a-single-function-call/40433 "2020-05-29T23:28:55Z")

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I need to solve a constrained non-linear optimization problem where the cost and constraints are computed via a vector-value function. E.g., instead of J = cost(x) c1 = constraint1(x) c2 = constraint2(x) I have, for ef…

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## [CUDAnative out of resources, but only when run from Atom/Juno?](https://discourse.julialang.org/t/cudanative-out-of-resources-but-only-when-run-from-atom-juno/40428)

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**Author:** [@Alex\_Ellison](https://discourse.julialang.org/u/Alex_Ellison)\
**Replies:** 2\
**Last updated:** [May 29, 2020, 10:20pm UTC](https://discourse.julialang.org/t/cudanative-out-of-resources-but-only-when-run-from-atom-juno/40428 "2020-05-29T22:20:16Z")

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Hey GPU Gang, I have a kernel I’m trying to execute with CUDAnative. I’ve tested it with Nvidia Visual Profiler and it uses 46 registers/thread, and I can achieve the theoretical max of 1024 threads/block when I run it …

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## [How to round down coefficients in a constraint in Julia/JuMP?](https://discourse.julialang.org/t/how-to-round-down-coefficients-in-a-constraint-in-julia-jump/29381)

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**Author:** [@Shor](https://discourse.julialang.org/u/Shor)\
**Replies:** 15\
**Last updated:** [May 29, 2020, 8:50pm UTC](https://discourse.julialang.org/t/how-to-round-down-coefficients-in-a-constraint-in-julia-jump/29381 "2020-05-29T20:50:31Z")

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Hi, I am new here. I don’t know how to round down coefficients in my constraints. (only coefficients in this constraint. I don’t want to round down elements in the given array) Anyone can help me? Thanks in advance!

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## [Link axes in Plots.jl](https://discourse.julialang.org/t/link-axes-in-plots-jl/40426)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 2\
**Last updated:** [May 29, 2020, 8:46pm UTC](https://discourse.julialang.org/t/link-axes-in-plots-jl/40426 "2020-05-29T20:46:55Z")

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I want to plot the projections of a 2d map on the right and below the 2d plot, but if I show the colorbar the axis are not aligned anymore. How can I align the axes? Is there a way to place the colorbar in the bottom r…

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## [\[DataFrames Question\]: Inner join DataFrame Array?](https://discourse.julialang.org/t/dataframes-question-inner-join-dataframe-array/40412)

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**Author:** [@Xijiang\_Yu](https://discourse.julialang.org/u/Xijiang_Yu)\
**Replies:** 4\
**Last updated:** [May 29, 2020, 2:24pm UTC](https://discourse.julialang.org/t/dataframes-question-inner-join-dataframe-array/40412 "2020-05-29T14:24:46Z")

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Question: Suppose I have an array of DataFrame t\[1:10\]. What is the neatest way to join them? innerjoin(t\[1\], t\[2\], ..., on = :tag, ...) # or df = t\[1\] for i in 2:10 df = innerjoin(df, t\[i\], on =...) end

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## [ChisqTest parameter theta0 not recognized](https://discourse.julialang.org/t/chisqtest-parameter-theta0-not-recognized/40348)

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**Author:** [@leclere](https://discourse.julialang.org/u/leclere)\
**Replies:** 2\
**Last updated:** [May 29, 2020, 9:47am UTC](https://discourse.julialang.org/t/chisqtest-parameter-theta0-not-recognized/40348 "2020-05-29T09:47:42Z")

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I am trying to use the ChisqTest function to check adequation between my empirical repartition and a theoretical probability distribution. Unfortunately it seems that parameter theta0 is not recognized. MWE: ChisqTest(…

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## [Blank plots from Gadfly in Juno](https://discourse.julialang.org/t/blank-plots-from-gadfly-in-juno/39975)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 7\
**Last updated:** [May 28, 2020, 10:03pm UTC](https://discourse.julialang.org/t/blank-plots-from-gadfly-in-juno/39975 "2020-05-28T22:03:46Z")

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I’m trying out Gadfly because I want to be able to zoom and pan on some data, and I’m having trouble getting plots to display in Juno. I’m using this example from the tutorial: using Gadfly, RDatasets iris = dataset("d…

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## [Stationary distribution with sparse transition matrix](https://discourse.julialang.org/t/stationary-distribution-with-sparse-transition-matrix/40301)

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**Author:** [@Honza9723](https://discourse.julialang.org/u/Honza9723)\
**Replies:** 7\
**Last updated:** [May 28, 2020, 9:37pm UTC](https://discourse.julialang.org/t/stationary-distribution-with-sparse-transition-matrix/40301 "2020-05-28T21:37:54Z")

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Dear All, I would like to ask for help/advice with following problem. I am solving the Hugget type of model (stationary distribution/transition) using the transition matrix approach (one AR(1) and one IID shock). In the…

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## [Slowdown with multiple instances per node?](https://discourse.julialang.org/t/slowdown-with-multiple-instances-per-node/40274)

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**Author:** [@sebastian-steiner](https://discourse.julialang.org/u/sebastian-steiner)\
**Replies:** 2\
**Last updated:** [May 27, 2020, 5:20pm UTC](https://discourse.julialang.org/t/slowdown-with-multiple-instances-per-node/40274 "2020-05-27T17:20:17Z")

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I am currently comparing MPI performance between C and Julia and when I only have a single task per node, Julia’s performance is pretty much exactly the same as C’s. But as soon as I utilize all 32 cores on both sockets,…

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## [How to convert ODBC.API.SQLGUID to String?](https://discourse.julialang.org/t/how-to-convert-odbc-api-sqlguid-to-string/39636)

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**Author:** [@ryszard314159](https://discourse.julialang.org/u/ryszard314159)\
**Replies:** 1\
**Last updated:** [May 27, 2020, 4:00pm UTC](https://discourse.julialang.org/t/how-to-convert-odbc-api-sqlguid-to-string/39636 "2020-05-27T16:00:32Z")

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Is there a way to convert SQLGUID to String? Apparently there convert() does not have corresponging method. julia\> x ODBC.API.SQLGUID(0x5715b932, 0x4bc5, 0x453c, (0x9d, 0xdb, 0x04, 0xe9, 0x2f, 0x4b, 0x69, 0x87)) julia\>…

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## [Passing a wrapped array to a kernel](https://discourse.julialang.org/t/passing-a-wrapped-array-to-a-kernel/40254)

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**Author:** [@emiwar](https://discourse.julialang.org/u/emiwar)\
**Replies:** 2\
**Last updated:** [May 27, 2020, 1:41pm UTC](https://discourse.julialang.org/t/passing-a-wrapped-array-to-a-kernel/40254 "2020-05-27T13:41:57Z")

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Hi, I’m trying to pass an object with a wrapped CuArray to a kernel: import CUDA struct MyStruct arrayField::CUDA.CuArray{Float32, 1, Nothing} end function f!(obj::MyStruct) id = CUDA.threadIdx().x if id \<=…

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## [Wher to find toy examples (with data) to check my (toy as well) implementation of ML algorithms?](https://discourse.julialang.org/t/wher-to-find-toy-examples-with-data-to-check-my-toy-as-well-implementation-of-ml-algorithms/40188)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [May 27, 2020, 11:45am UTC](https://discourse.julialang.org/t/wher-to-find-toy-examples-with-data-to-check-my-toy-as-well-implementation-of-ml-algorithms/40188 "2020-05-27T11:45:06Z")

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I am developing a toy ML package, but I would like to test it with some simple datasets and implementation in established packages… is there a repository with simple data/algorithm (not necessarily in Julia) to see how m…

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## [Some more basic plots with Plots.jl for illustrating calculous and linear algebra books, but can we write better plotting codes?](https://discourse.julialang.org/t/some-more-basic-plots-with-plots-jl-for-illustrating-calculous-and-linear-algebra-books-but-can-we-write-better-plotting-codes/40168)

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**Author:** [@HaoLi111](https://discourse.julialang.org/u/HaoLi111)\
**Replies:** 0\
**Last updated:** [May 26, 2020, 6:40am UTC](https://discourse.julialang.org/t/some-more-basic-plots-with-plots-jl-for-illustrating-calculous-and-linear-algebra-books-but-can-we-write-better-plotting-codes/40168 "2020-05-26T06:40:52Z")

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I started re-making the plots to illustrate some mathematical ideas. The repo is for illustrating the basic ideas through easily created plots and animations and the use and tuning of parameters of Plots.jl This is le…

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## [\[ANN\]: Turing 0.13.0 - MLE/MAP and prediction](https://discourse.julialang.org/t/ann-turing-0-13-0-mle-map-and-prediction/40033)

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**Author:** [@cpfiffer](https://discourse.julialang.org/u/cpfiffer)\
**Replies:** 6\
**Last updated:** [May 25, 2020, 10:48pm UTC](https://discourse.julialang.org/t/ann-turing-0-13-0-mle-map-and-prediction/40033 "2020-05-25T22:48:12Z")

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We’re happy to announce Turing 0.13.0, which brings a suite of much-needed features. I am particularly happy about this one because it is a feature-rich release, which is always fun. Maximum likelihood and maximum a pos…

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## [Full border with ticks](https://discourse.julialang.org/t/full-border-with-ticks/25060)

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**Author:** [@Milo\_Guerrero](https://discourse.julialang.org/u/Milo_Guerrero)\
**Replies:** 11\
**Last updated:** [May 25, 2020, 10:03pm UTC](https://discourse.julialang.org/t/full-border-with-ticks/25060 "2020-05-25T22:03:46Z")

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Hello, Im a using the plots library with gr(), I’ve tried to obtain a graphic with full border and ticks but I don’t know how, my last try is: plot(equation, markershape = :hexagon,xticks = ( \[0:5:100;\], \["\\\\theta", "2\\…

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## [lhe/Biofast benchmark | FASTQ parsing \[Julia,Nim,Crystal,Python,...\]](https://discourse.julialang.org/t/lhe-biofast-benchmark-fastq-parsing-julia-nim-crystal-python/39747)

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**Author:** [@ImreSamu](https://discourse.julialang.org/u/ImreSamu)\
**Replies:** 54\
**Last updated:** [May 25, 2020, 8:17pm UTC](https://discourse.julialang.org/t/lhe-biofast-benchmark-fastq-parsing-julia-nim-crystal-python/39747 "2020-05-25T20:17:43Z")

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from the community news: " Biofast is a small benchmark for evaluating the performance of programming languages and implementations on a few common tasks in the field of Bioinformatics. It currently includes two benchma…

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## [Counts of unique values per group in a DataFrame](https://discourse.julialang.org/t/counts-of-unique-values-per-group-in-a-dataframe/40088)

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**Author:** [@kevin.squire](https://discourse.julialang.org/u/kevin.squire)\
**Replies:** 3\
**Last updated:** [May 25, 2020, 3:25pm UTC](https://discourse.julialang.org/t/counts-of-unique-values-per-group-in-a-dataframe/40088 "2020-05-25T15:25:27Z")

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Hi, I’m trying to determine unique counts of values in a column per group in a DataFrame. As an example, given the following: using DataFrames julia\> df = DataFrame(lab = \[repeat(\["Lab1"\], 4)...; repeat(\["Lab2"\], 5).…

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