# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=562

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**Page:** 563

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## [Julia: DataFramesMeta Transformation](https://discourse.julialang.org/t/julia-dataframesmeta-transformation/3435)

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**Author:** [@alasaadstat](https://discourse.julialang.org/u/alasaadstat)\
**Replies:** 4\
**Last updated:** [April 30, 2017, 6:54pm UTC](https://discourse.julialang.org/t/julia-dataframesmeta-transformation/3435 "2017-04-30T18:54:46Z")

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This question is already posted at StackOverflow on this link: DataFramesMeta Transformation. @ChrisRackauckas introduced me to this forum and so I’m hoping someone might be able to help me about my problem. I’m trying t…

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## [Calculate slacks for quadratic constraints](https://discourse.julialang.org/t/calculate-slacks-for-quadratic-constraints/3425)

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**Author:** [@adowling2](https://discourse.julialang.org/u/adowling2)\
**Replies:** 2\
**Last updated:** [April 29, 2017, 5:45pm UTC](https://discourse.julialang.org/t/calculate-slacks-for-quadratic-constraints/3425 "2017-04-29T17:45:37Z")

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I’d like to calculate the slacks for a quadratic constraint. Using MathProgBase.getconstrmatrix (see old Google Groups post) does not work for quadratic constraints. Any suggestions?

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## [Recommended packages to contribute to for newcomers?](https://discourse.julialang.org/t/recommended-packages-to-contribute-to-for-newcomers/3416)

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**Author:** [@ajkeith](https://discourse.julialang.org/u/ajkeith)\
**Replies:** 2\
**Last updated:** [April 28, 2017, 1:03pm UTC](https://discourse.julialang.org/t/recommended-packages-to-contribute-to-for-newcomers/3416 "2017-04-28T13:03:34Z")

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Hello! I’ve been using Julia for homework and I’m interested in getting more involved in package development. In the near term I’d like to contribute to some stats packages to get a feel for how packages work, with a lon…

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## [Matrix Vector Operations to For Loop](https://discourse.julialang.org/t/matrix-vector-operations-to-for-loop/3394)

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**Author:** [@mcovalt](https://discourse.julialang.org/u/mcovalt)\
**Replies:** 5\
**Last updated:** [April 27, 2017, 10:29pm UTC](https://discourse.julialang.org/t/matrix-vector-operations-to-for-loop/3394 "2017-04-27T22:29:40Z")

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This could be wishful thinking, but it would be neat if this has been or could be implemented nicely. For my program I have lots of linear operators and maps in the form of sparse matrices. The non-zero structure and va…

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## [Segmented\_sum in Knet](https://discourse.julialang.org/t/segmented-sum-in-knet/3396)

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**Author:** [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)\
**Replies:** 0\
**Last updated:** [April 27, 2017, 5:55am UTC](https://discourse.julialang.org/t/segmented-sum-in-knet/3396 "2017-04-27T05:55:03Z")

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Hello, I have started to play with Knet, but I am unable to reproduce my work related to multi-instance learning in it, since I need segmented\_sum operation from tensorflow. I have created a small example using Knet u…

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## [LoadError: MethodError: no method matching quantile(::Distributions.JohnsonSU{Float64}, ::Float64)](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-quantile-distributions-johnsonsu-float64-float64/3371)

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**Author:** [@Wael\_Sboui](https://discourse.julialang.org/u/Wael_Sboui)\
**Replies:** 2\
**Last updated:** [April 26, 2017, 8:03pm UTC](https://discourse.julialang.org/t/loaderror-methoderror-no-method-matching-quantile-distributions-johnsonsu-float64-float64/3371 "2017-04-26T20:03:06Z")

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Hi smart community, I faced this problem after having added a univariate continuous to Distributions.jl and univariates.jl Always working on Julia 0.5.1. However, I didn’t face any similar problem when I was on Julia 0.…

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## [ODE Solver with ApproxFun's that change over time](https://discourse.julialang.org/t/ode-solver-with-approxfuns-that-change-over-time/3379)

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**Author:** [@anodos](https://discourse.julialang.org/u/anodos)\
**Replies:** 2\
**Last updated:** [April 26, 2017, 3:23pm UTC](https://discourse.julialang.org/t/ode-solver-with-approxfuns-that-change-over-time/3379 "2017-04-26T15:23:17Z")

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Hi, I’m looking for an ODE solver that can solve DE’s of the form: dydt = f(t,y) where the ‘y’ are themselves ApproxFun functions (i.e. Chebychev interpolations of a function.) A very simple example might be the funct…

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## [LoadError: error in method definition: function Base.min must be explicitly imported to be extended](https://discourse.julialang.org/t/loaderror-error-in-method-definition-function-base-min-must-be-explicitly-imported-to-be-extended/3362)

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**Author:** [@Wael\_Sboui](https://discourse.julialang.org/u/Wael_Sboui)\
**Replies:** 3\
**Last updated:** [April 25, 2017, 2:03pm UTC](https://discourse.julialang.org/t/loaderror-error-in-method-definition-function-base-min-must-be-explicitly-imported-to-be-extended/3362 "2017-04-25T14:03:55Z")

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Hi everybody, I’m working under Julia 0.5.1 and I face this problem below: Error evaluating AirplaneRealStats5.9.jl LoadError: LoadError: error in method definition: function Base.min must be explicitly imported to be …

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## [Pushing irregular updates w/ HttpServer & Server Sent Events / Websockets](https://discourse.julialang.org/t/pushing-irregular-updates-w-httpserver-server-sent-events-websockets/3344)

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**Author:** [@m-j-w](https://discourse.julialang.org/u/m-j-w)\
**Replies:** 4\
**Last updated:** [April 23, 2017, 8:23pm UTC](https://discourse.julialang.org/t/pushing-irregular-updates-w-httpserver-server-sent-events-websockets/3344 "2017-04-23T20:23:22Z")

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Recently I had the idea to add a web server to a long running computation, which should give essentially updates on the status of the computation to all connected browsers by simply pushing the new data at rather large i…

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## [Partially blackbox optimization with JuMP?](https://discourse.julialang.org/t/partially-blackbox-optimization-with-jump/3335)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 1\
**Last updated:** [April 22, 2017, 12:23pm UTC](https://discourse.julialang.org/t/partially-blackbox-optimization-with-jump/3335 "2017-04-22T12:23:36Z")

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I have a problem which I have been using NLopt to solve, but am interested in converting it into a JuMP model to try other solvers and also get some autodifferentiation. The problem is that the objective function is a bl…

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## [Finite Element Computations On A Cluster Using Petsc.jl](https://discourse.julialang.org/t/finite-element-computations-on-a-cluster-using-petsc-jl/3287)

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**Author:** [@hiemstar](https://discourse.julialang.org/u/hiemstar)\
**Replies:** 2\
**Last updated:** [April 21, 2017, 2:41pm UTC](https://discourse.julialang.org/t/finite-element-computations-on-a-cluster-using-petsc-jl/3287 "2017-04-21T14:41:53Z")

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I want to write a parallel distributed isogeometric analysis solver for linear and non-linear elastostatics problems using Julia. For this purpose I need access to distributed linear and non-linear solvers. My first th…

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## [ANN: MLDataPattern.jl](https://discourse.julialang.org/t/ann-mldatapattern-jl/3299)

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**Author:** [@Evizero](https://discourse.julialang.org/u/Evizero)\
**Replies:** 6\
**Last updated:** [April 21, 2017, 1:32pm UTC](https://discourse.julialang.org/t/ann-mldatapattern-jl/3299 "2017-04-21T13:32:24Z")

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Hello everyone! I am really happy to finally announce the next JuliaML package reaching a stable state: MLDataPattern.jl Github: GitHub - JuliaML/MLDataPattern.jl: Utility package for subsetting, resampling, iteration,…

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## [Plotting a StatsBase.Histogram](https://discourse.julialang.org/t/plotting-a-statsbase-histogram/3293)

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**Author:** [@jstrube](https://discourse.julialang.org/u/jstrube)\
**Replies:** 2\
**Last updated:** [April 21, 2017, 5:31am UTC](https://discourse.julialang.org/t/plotting-a-statsbase-histogram/3293 "2017-04-21T05:31:05Z")

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Another particle physicist who likes step histograms here. I’ve googled and came across this: https://github.com/JuliaStats/StatsBase.jl/pull/243 I very much like the plots shown here, but this doesn’t seem to work (a…

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## [Memory using in a for loop](https://discourse.julialang.org/t/memory-using-in-a-for-loop/3305)

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**Author:** [@Yankai\_Cao](https://discourse.julialang.org/u/Yankai_Cao)\
**Replies:** 3\
**Last updated:** [April 21, 2017, 1:58am UTC](https://discourse.julialang.org/t/memory-using-in-a-for-loop/3305 "2017-04-21T01:58:16Z")

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I find that if I create and solve models in a for loop, then the memory usage will increase dramatically. I would expect the memory allocated keeps constant. Here is the test code: using JuMP, SCIP #,Gurobi function …

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## [Regular Expression](https://discourse.julialang.org/t/regular-expression/753)

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**Author:** [@alphasig329](https://discourse.julialang.org/u/alphasig329)\
**Replies:** 4\
**Last updated:** [April 20, 2017, 7:41pm UTC](https://discourse.julialang.org/t/regular-expression/753 "2017-04-20T19:41:42Z")

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Hello, I am trying to convert my data management code from R to Julia with some minor challenges. In particular, I am trying to use regular expression to extract patterns between two words. For example, test = “Top Ski…

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## [How to get ODBC to work with postgresql](https://discourse.julialang.org/t/how-to-get-odbc-to-work-with-postgresql/3169)

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**Author:** [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Replies:** 1\
**Last updated:** [April 20, 2017, 9:40am UTC](https://discourse.julialang.org/t/how-to-get-odbc-to-work-with-postgresql/3169 "2017-04-20T09:40:16Z")

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Operating system: Debian Testing/Sid Julia version: 4.7.2 and 0.6.0-pre.beta.91. The same happens on both versions. I have installed unixodbc and odbc-postgresql and can connect to my database with isql. Following th…

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## [Problem with Julia Ipopt](https://discourse.julialang.org/t/problem-with-julia-ipopt/3223)

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**Author:** [@Angshuman\_Goswami](https://discourse.julialang.org/u/Angshuman_Goswami)\
**Replies:** 4\
**Last updated:** [April 18, 2017, 9:29pm UTC](https://discourse.julialang.org/t/problem-with-julia-ipopt/3223 "2017-04-18T21:29:02Z")

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I am trying to do vehicle control. I am trying to use the magic formula which is given by @defNLExpr(mdl, FyR\[i = 1:N\] , Dsin(Catan(B \* (atan((v\_y\[i\] - b\*r\[i\])/v\_x\[i\])))) ) Now when i run the code i am …

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## [ODBC initialization issues](https://discourse.julialang.org/t/odbc-initialization-issues/3241)

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**Author:** [@jkbest2](https://discourse.julialang.org/u/jkbest2)\
**Replies:** 7\
**Last updated:** [April 18, 2017, 6:10am UTC](https://discourse.julialang.org/t/odbc-initialization-issues/3241 "2017-04-18T06:10:38Z")

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I have successfully used ODBC.jl to retrieve data from a PostgreSQL server in the past (on Ubuntu). I’m trying to recreate my setup on Arch Linux, and running into problems when I load the ODBC package. I am using the sa…

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## [Suggested formats for saving and serialization](https://discourse.julialang.org/t/suggested-formats-for-saving-and-serialization/3230)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 8\
**Last updated:** [April 17, 2017, 7:23pm UTC](https://discourse.julialang.org/t/suggested-formats-for-saving-and-serialization/3230 "2017-04-17T19:23:29Z")

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I was wondering what the suggested formats for saving and serializing are these days. I am really confused about the landscape of DataTables, DataFrames, databases, etc. I was hoping to write a few functions for the Diff…

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## [RFC: Requiring Documenter.jl minor version to be fixed](https://discourse.julialang.org/t/rfc-requiring-documenter-jl-minor-version-to-be-fixed/3243)

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**Author:** [@mortenpi](https://discourse.julialang.org/u/mortenpi)\
**Replies:** 4\
**Last updated:** [April 17, 2017, 7:10am UTC](https://discourse.julialang.org/t/rfc-requiring-documenter-jl-minor-version-to-be-fixed/3243 "2017-04-17T07:10:34Z")

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This is addressed to package developers using Documenter.jl to build their docs. I would like to gather some feedback on whether fixing the minor version of Documenter should be the recommended practice for Documenter de…

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## [MySQL error while precompling](https://discourse.julialang.org/t/mysql-error-while-precompling/885)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 10\
**Last updated:** [April 15, 2017, 2:56pm UTC](https://discourse.julialang.org/t/mysql-error-while-precompling/885 "2017-04-15T14:56:57Z")

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Hi all- I am using Julia .5 on Ubuntu 16.04. When I try to use MySQL I get the following message. Is there something else I need to configure? Thanks, Chris ERROR: LoadError: LoadError: MYSQL library not found in ma…

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## [How to handle and store large amounts of (distributed) generated data?](https://discourse.julialang.org/t/how-to-handle-and-store-large-amounts-of-distributed-generated-data/3231)

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**Author:** [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Replies:** 4\
**Last updated:** [April 15, 2017, 12:15pm UTC](https://discourse.julialang.org/t/how-to-handle-and-store-large-amounts-of-distributed-generated-data/3231 "2017-04-15T12:15:39Z")

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A lot of (Monte Carlo) simulations can be done simultaneously and independently on many nodes of an HPC, each generating large solutions for later analysis. However, a straight pmap will try to build a giant output that …

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## [Scipy using PyCall in Julia](https://discourse.julialang.org/t/scipy-using-pycall-in-julia/3207)

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**Author:** [@pmarg](https://discourse.julialang.org/u/pmarg)\
**Replies:** 6\
**Last updated:** [April 14, 2017, 10:02am UTC](https://discourse.julialang.org/t/scipy-using-pycall-in-julia/3207 "2017-04-14T10:02:51Z")

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I have a moderately large system of non-linear equations that I want to solve using scipy.optimize in Julia. The problem is that I store the equations in a vector before I pass them to the solver and PyCall doesn’t accep…

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## [Changing default printing options in JuMP](https://discourse.julialang.org/t/changing-default-printing-options-in-jump/1602)

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**Author:** [@huckl3b3rry87](https://discourse.julialang.org/u/huckl3b3rry87)\
**Replies:** 1\
**Last updated:** [April 14, 2017, 4:47am UTC](https://discourse.julialang.org/t/changing-default-printing-options-in-jump/1602 "2017-04-14T04:47:40Z")

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Is there a way to change the default printing options? Specifically, I am using getdual() and it is returning values like 0.0 and I want to see more of this number

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## [Mocha Type assert failure](https://discourse.julialang.org/t/mocha-type-assert-failure/3189)

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**Author:** [@dryden4482](https://discourse.julialang.org/u/dryden4482)\
**Replies:** 0\
**Last updated:** [April 12, 2017, 10:43pm UTC](https://discourse.julialang.org/t/mocha-type-assert-failure/3189 "2017-04-12T22:43:00Z")

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Load error in loading a snapshot. The error is somewhat random. Sometimes it works, other times it does not. I believe the compose package is interfering with mocha. TypeError: read\_refs: in typeassert, expected Array{A…

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## [Modeling concurrency](https://discourse.julialang.org/t/modeling-concurrency/3172)

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**Author:** [@bo-lo](https://discourse.julialang.org/u/bo-lo)\
**Replies:** 2\
**Last updated:** [April 12, 2017, 1:07pm UTC](https://discourse.julialang.org/t/modeling-concurrency/3172 "2017-04-12T13:07:54Z")

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Hi I am just starting with Julia and would like to model concurrency as in digital circuits. A trivial example would be to model a 3 bit counter and see its output in a waveform viewer. A more evolved example would be …

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## [Binomial distribution without Distributions.jl?](https://discourse.julialang.org/t/binomial-distribution-without-distributions-jl/3176)

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**Author:** [@anon94023334](https://discourse.julialang.org/u/anon94023334)\
**Replies:** 11\
**Last updated:** [April 11, 2017, 11:57pm UTC](https://discourse.julialang.org/t/binomial-distribution-without-distributions-jl/3176 "2017-04-11T23:57:19Z")

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Hi all, This is not intended to be a knock on the excellent Distributions.jl package - we’ve used it happily for several years in LightGraphs and it’s working wonderfully. We currently have an initiative to make LightG…

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## [t-SNE visualization](https://discourse.julialang.org/t/t-sne-visualization/3150)

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**Author:** [@hpoit](https://discourse.julialang.org/u/hpoit)\
**Replies:** 0\
**Last updated:** [April 10, 2017, 9:25pm UTC](https://discourse.julialang.org/t/t-sne-visualization/3150 "2017-04-10T21:25:46Z")

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Hi @malmaud, I’ve read all your files in TensorFlow.jl/docs/src/, thanks for that. Is there an advantage to integrating t-SNE to TensorFlow.jl? I’m not sure how I would use it separately either (haven’t studied it yet).…

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## [Feather.jl, and understanding when data is loaded into RAM](https://discourse.julialang.org/t/feather-jl-and-understanding-when-data-is-loaded-into-ram/3173)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 0\
**Last updated:** [April 11, 2017, 4:50pm UTC](https://discourse.julialang.org/t/feather-jl-and-understanding-when-data-is-loaded-into-ram/3173 "2017-04-11T16:50:51Z")

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Like a lot of people, I have a great deal of use for binary serialization formats for storing tabular data. I really love Feather which is based on the new Apache Arrow format. However, its usefulness is extremely limi…

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## [Slow complex exponential evaluation](https://discourse.julialang.org/t/slow-complex-exponential-evaluation/3170)

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**Author:** [@pkairys](https://discourse.julialang.org/u/pkairys)\
**Replies:** 8\
**Last updated:** [April 11, 2017, 3:45pm UTC](https://discourse.julialang.org/t/slow-complex-exponential-evaluation/3170 "2017-04-11T15:45:20Z")

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I am having some issues with code and I can’t seem to reach a solution. Specifically I am re-writing some Matlab code and for one or two things I can’t seem to match the speed of Matlab. Matlab Code: a=\[0:2^24-1\] b=exp…

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