# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1086

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

**Page:** 1087

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## [Recommended Quickcheck library](https://discourse.julialang.org/t/recommended-quickcheck-library/78475)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 1\
**Last updated:** [March 25, 2022, 6:15pm UTC](https://discourse.julialang.org/t/recommended-quickcheck-library/78475 "2022-03-25T18:15:48Z")

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Hi, is there a recommended library similary to Haskel’s QuickCheck that is still maintained? I have found QuickCheck.jl and RandomizedPropertyTest.jl but both seem abandoned. Any other recommendations? Thanks!

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## [Combining lots of DataFrames, best approach?](https://discourse.julialang.org/t/combining-lots-of-dataframes-best-approach/78466)

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**Author:** [@tbeason](https://discourse.julialang.org/u/tbeason)\
**Replies:** 10\
**Last updated:** [March 25, 2022, 6:05pm UTC](https://discourse.julialang.org/t/combining-lots-of-dataframes-best-approach/78466 "2022-03-25T18:05:38Z")

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I am wondering if there are better ways to append lots of DataFrames together in these two scenarios. # dts is a vector of lots of dataframes (\>1000) # here is a MWE version of it dts = \[DataFrame(pid=fill(string(rand(U…

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## [Simulation running well on K620 but instable on A100?](https://discourse.julialang.org/t/simulation-running-well-on-k620-but-instable-on-a100/77584)

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**Author:** [@Ludovic\_Dumoulin](https://discourse.julialang.org/u/Ludovic_Dumoulin)\
**Replies:** 15\
**Last updated:** [March 25, 2022, 5:36pm UTC](https://discourse.julialang.org/t/simulation-running-well-on-k620-but-instable-on-a100/77584 "2022-03-25T17:36:41Z")

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Hello, I am facing a difficult situation. I am new to GPU computing and I am debugging my code on my computer gpu (an old K620) and then run my simulation on a cluster with A100 cards. The simulation is stable for a l…

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## [Base including notnan, notnothing, ...?](https://discourse.julialang.org/t/base-including-notnan-notnothing/78458)

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**Author:** [@markmbaum](https://discourse.julialang.org/u/markmbaum)\
**Replies:** 9\
**Last updated:** [March 25, 2022, 5:24pm UTC](https://discourse.julialang.org/t/base-including-notnan-notnothing/78458 "2022-03-25T17:24:42Z")

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has there been discussion about including a notnan function and its analogs like notnothing in the Base library? I frequently find myself doing things like filter(x -\> !isnan(x), Y) where it would be nice to simply fi…

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## [Anyone building a kafka streaming platform for Julia similar to Faust for Python?](https://discourse.julialang.org/t/anyone-building-a-kafka-streaming-platform-for-julia-similar-to-faust-for-python/39513)

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**Author:** [@schlichtanders](https://discourse.julialang.org/u/schlichtanders)\
**Replies:** 8\
**Last updated:** [March 25, 2022, 5:00pm UTC](https://discourse.julialang.org/t/anyone-building-a-kafka-streaming-platform-for-julia-similar-to-faust-for-python/39513 "2022-03-25T17:00:05Z")

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Hi all, I am very excited about the future of Julia’s streaming usecases. With Transducers.jl and OnlineStats.jl there is already a rich foundation established. What I am unable to find is a streaming library similar t…

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## [How to preallocate a triangular matrix and overwrite it with cholesky!](https://discourse.julialang.org/t/how-to-preallocate-a-triangular-matrix-and-overwrite-it-with-cholesky/78463)

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**Author:** [@LuZhangstat](https://discourse.julialang.org/u/LuZhangstat)\
**Replies:** 9\
**Last updated:** [March 25, 2022, 3:37pm UTC](https://discourse.julialang.org/t/how-to-preallocate-a-triangular-matrix-and-overwrite-it-with-cholesky/78463 "2022-03-25T15:37:29Z")

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Hi everyone, I am trying to improve my code’s efficiency. I locate a line that might be too expensive, but I failed to figure out how to improve it. In brief, I need to save the inverse of an N by N covariance matrix of…

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## [Use of "export" keyword](https://discourse.julialang.org/t/use-of-export-keyword/78457)

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**Author:** [@iAnkiit](https://discourse.julialang.org/u/iAnkiit)\
**Replies:** 3\
**Last updated:** [March 25, 2022, 3:01pm UTC](https://discourse.julialang.org/t/use-of-export-keyword/78457 "2022-03-25T15:01:38Z")

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What is the actual use of keyword “export” ? I have read julia documentation , but not very clear. What if we dont use export at all?

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## [How to make an executable work on different machines (make a dynamic path)?](https://discourse.julialang.org/t/how-to-make-an-executable-work-on-different-machines-make-a-dynamic-path/78236)

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**Author:** [@Amro](https://discourse.julialang.org/u/Amro)\
**Replies:** 6\
**Last updated:** [March 25, 2022, 12:49pm UTC](https://discourse.julialang.org/t/how-to-make-an-executable-work-on-different-machines-make-a-dynamic-path/78236 "2022-03-25T12:49:00Z")

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I have created a project folder TESTEXE and built an executable as below: module testexe Base.@ccallable function julia\_main()::Cint try testApp() catch Base.invokelatest(Base.display\_error, B…

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## [JuMP with user-defined non linear functions](https://discourse.julialang.org/t/jump-with-user-defined-non-linear-functions/78299)

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**Author:** [@dkc94](https://discourse.julialang.org/u/dkc94)\
**Replies:** 3\
**Last updated:** [March 25, 2022, 12:43pm UTC](https://discourse.julialang.org/t/jump-with-user-defined-non-linear-functions/78299 "2022-03-25T12:43:10Z")

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Hi everyone! I am new to Julia and I am trying to solve a highly non linear optimization problem. I am encountering a problem when registering the objective function and very little idea about what could be going on. He…

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## [Speed up ArchGDAL.contains for thousands of data](https://discourse.julialang.org/t/speed-up-archgdal-contains-for-thousands-of-data/77847)

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**Author:** [@Frankiewaang](https://discourse.julialang.org/u/Frankiewaang)\
**Replies:** 8\
**Last updated:** [March 25, 2022, 12:39pm UTC](https://discourse.julialang.org/t/speed-up-archgdal-contains-for-thousands-of-data/77847 "2022-03-25T12:39:52Z")

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Hi Guys, I have geopoints like this import ArchGDAL as AG lon = LinRange(-180,180,7500) lat = LinRange(-90,90,5500) function meshgrid(x, y) X = \[i for i in x, j in 1:length(y)\] Y = \[j for i in 1:length(x), j i…

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## [How to draw minus infty using latex?](https://discourse.julialang.org/t/how-to-draw-minus-infty-using-latex/78454)

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**Author:** [@jcbritobr](https://discourse.julialang.org/u/jcbritobr)\
**Replies:** 4\
**Last updated:** [March 25, 2022, 12:33pm UTC](https://discourse.julialang.org/t/how-to-draw-minus-infty-using-latex/78454 "2022-03-25T12:33:07Z")

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Hello, good morning. Im trying to draw integration unicode for -oo +oo infinity reprensentation but stucked only on this: My goal is to draw minus symbol and get this: Im using this code now $$\\int\_\\infty^\\infty x…

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## [How to host your deep learning model trained in flux](https://discourse.julialang.org/t/how-to-host-your-deep-learning-model-trained-in-flux/41561)

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**Author:** [@AbhimanyuAryan](https://discourse.julialang.org/u/AbhimanyuAryan)\
**Replies:** 7\
**Last updated:** [March 25, 2022, 8:05am UTC](https://discourse.julialang.org/t/how-to-host-your-deep-learning-model-trained-in-flux/41561 "2022-03-25T08:05:25Z")

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How to host your saved julia flux model on web? Like Pytorch and Flask are used

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## [JuMP : optimize!(model)](https://discourse.julialang.org/t/jump-optimize-model/78445)

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**Author:** [@iAnkiit](https://discourse.julialang.org/u/iAnkiit)\
**Replies:** 1\
**Last updated:** [March 25, 2022, 7:59am UTC](https://discourse.julialang.org/t/jump-optimize-model/78445 "2022-03-25T07:59:22Z")

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Why do we need solvers , if we can solve model with : optimize!(model\_name) ? How optimize! works? What solvers actually does ? What if we don’t define solvers?

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## [Why does BenchmarkTools \`@belapsed\` make so many allocations?](https://discourse.julialang.org/t/why-does-benchmarktools-belapsed-make-so-many-allocations/78433)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 2\
**Last updated:** [March 25, 2022, 5:07am UTC](https://discourse.julialang.org/t/why-does-benchmarktools-belapsed-make-so-many-allocations/78433 "2022-03-25T05:07:24Z")

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For a long time, I have been hard-coding my own benchmarks using expressions like minimum(@elapsed f() for \_ in 1:samples). It was brought to my attention that BenchmarkTools.jl does this kind of repeated sampling automa…

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## [ANN: Package for simulation of shells and beams](https://discourse.julialang.org/t/ann-package-for-simulation-of-shells-and-beams/78429)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 0\
**Last updated:** [March 24, 2022, 10:28pm UTC](https://discourse.julialang.org/t/ann-package-for-simulation-of-shells-and-beams/78429 "2022-03-24T22:28:51Z")

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The following package for finite element analysis of beams and shells has reached maturity: https://github.com/PetrKryslUCSD/FinEtoolsFlexStructures.jl Written entirely in Julia, the performance in linear shell problem…

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## [ANN: JuMP 1.0 is released](https://discourse.julialang.org/t/ann-jump-1-0-is-released/78425)

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**Author:** [@odow](https://discourse.julialang.org/u/odow)\
**Replies:** 5\
**Last updated:** [March 25, 2022, 2:53am UTC](https://discourse.julialang.org/t/ann-jump-1-0-is-released/78425 "2022-03-25T02:53:56Z")

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Dear all, We are very pleased to announce the release of JuMP 1.0! You can read more about it here: JuMP 1.0.0 is released | JuMP A big thank you to all of the contributors over the last (nearly) 10 years! You can fin…

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## [Reversing a range of \`UInt8\`s yields an empty set](https://discourse.julialang.org/t/reversing-a-range-of-uint8-s-yields-an-empty-set/78434)

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**Author:** [@maxkapur](https://discourse.julialang.org/u/maxkapur)\
**Replies:** 4\
**Last updated:** [March 25, 2022, 2:24am UTC](https://discourse.julialang.org/t/reversing-a-range-of-uint8-s-yields-an-empty-set/78434 "2022-03-25T02:24:52Z")

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Is this a bug or not? (v1.7.0) julia\> UInt8(1):UInt8(12) |\> collect 12-element Vector{UInt8}: 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c julia\> reverse(UInt8(1):UInt8(12)) |\> collect UInt8\[…

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## [Advice to make getfield(::NamedTuple, ::Symbol) typestable](https://discourse.julialang.org/t/advice-to-make-getfield-namedtuple-symbol-typestable/78340)

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**Author:** [@ianfiske](https://discourse.julialang.org/u/ianfiske)\
**Replies:** 19\
**Last updated:** [March 25, 2022, 12:29am UTC](https://discourse.julialang.org/t/advice-to-make-getfield-namedtuple-symbol-typestable/78340 "2022-03-25T00:29:54Z")

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I have a complicated nested NamedTuple, where profiling shows that getindex on the NamedTuple is a significant source of slowness. @code\_warntype shows a type instability from getindex on that NamedTuple in the slow cal…

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## [Nesting a for loop in a while loop](https://discourse.julialang.org/t/nesting-a-for-loop-in-a-while-loop/78336)

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**Author:** [@phantom](https://discourse.julialang.org/u/phantom)\
**Replies:** 6\
**Last updated:** [March 25, 2022, 12:24am UTC](https://discourse.julialang.org/t/nesting-a-for-loop-in-a-while-loop/78336 "2022-03-25T00:24:54Z")

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Hi, I apologize if this is a very elementary mistake but I still struggling with programming and Julia. I would like to iterate through a list while a certain conditions hold true. I would also like to be able to stop…

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## ["Crunch" RGB pixels into 0-1 range](https://discourse.julialang.org/t/crunch-rgb-pixels-into-0-1-range/78428)

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**Author:** [@theta](https://discourse.julialang.org/u/theta)\
**Replies:** 3\
**Last updated:** [March 24, 2022, 11:17pm UTC](https://discourse.julialang.org/t/crunch-rgb-pixels-into-0-1-range/78428 "2022-03-24T23:17:36Z")

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Hi, I’m messing around with image generation in Julia. I just realized that some of the pixels I’m generating have red, green, or blue values outside of the range \[0,1\]. For example, one of my pixels looks like RGB{Floa…

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## [DataFrame column names into GLM as variable names](https://discourse.julialang.org/t/dataframe-column-names-into-glm-as-variable-names/78422)

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**Author:** [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Replies:** 2\
**Last updated:** [March 24, 2022, 10:43pm UTC](https://discourse.julialang.org/t/dataframe-column-names-into-glm-as-variable-names/78422 "2022-03-24T22:43:38Z")

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I would like to use GLM to estimate 500 regressions like beta\[1\] = coef(lm(@formula(AAPL ~ SP500), Stocks))\[2\] beta\[2\] = coef(lm(@formula(AMGN ~ SP500), Stocks))\[2\] … beta\[i\] = coef(lm(@formula(col\_i ~ SP500), Stocks…

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## [Reducing allocations (again)](https://discourse.julialang.org/t/reducing-allocations-again/78408)

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**Author:** [@lancejnelson](https://discourse.julialang.org/u/lancejnelson)\
**Replies:** 10\
**Last updated:** [March 24, 2022, 10:34pm UTC](https://discourse.julialang.org/t/reducing-allocations-again/78408 "2022-03-24T22:34:15Z")

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I still don’t have great intuition for quickly spotting my bottlenecks due to unneeded allocations and the associated work around. Here is some code I’m trying to optimize right now: function logpost(w,data,μ,Σ) po…

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## [Tools in Julia for development and production -- Notebooks and Pluto](https://discourse.julialang.org/t/tools-in-julia-for-development-and-production-notebooks-and-pluto/78415)

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**Author:** [@LispyArnuld](https://discourse.julialang.org/u/LispyArnuld)\
**Replies:** 3\
**Last updated:** [March 24, 2022, 8:16pm UTC](https://discourse.julialang.org/t/tools-in-julia-for-development-and-production-notebooks-and-pluto/78415 "2022-03-24T20:16:45Z")

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I have experience in C. When I learned Python, I learned that Python is way easier to learn using IPython and for production work good tools exist like Jupyter Notebook (now Jupyter Lab) and virtual environments (venv e.…

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## [Another slowdown when using \`Threads.@threads\`?](https://discourse.julialang.org/t/another-slowdown-when-using-threads-threads/78009)

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**Author:** [@goerch](https://discourse.julialang.org/u/goerch)\
**Replies:** 11\
**Last updated:** [March 24, 2022, 8:12pm UTC](https://discourse.julialang.org/t/another-slowdown-when-using-threads-threads/78009 "2022-03-24T20:12:06Z")

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The MWE using LinearAlgebra using Random using BenchmarkTools function distance(x, y, p::Real = 2) norm((x\[1\] - y\[1\], x\[2\] - y\[2\]), p) end function jfa\_serial!(grid, sites, p::Real=2) for (color, (x, y)) in en…

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## [Help to correct this code please](https://discourse.julialang.org/t/help-to-correct-this-code-please/78421)

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**Author:** [@Eric.O](https://discourse.julialang.org/u/Eric.O)\
**Replies:** 2\
**Last updated:** [March 24, 2022, 7:29pm UTC](https://discourse.julialang.org/t/help-to-correct-this-code-please/78421 "2022-03-24T19:29:33Z")

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I want to write the code below in Julia but I keep getting the error MethodError: no method matching getindex(::VariableRef, ::Int64) Any help will be appreciated please. Thank you for your help. using JuMP using Mo…

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## [Equivalent of old syntax @constraintref](https://discourse.julialang.org/t/equivalent-of-old-syntax-constraintref/78315)

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**Author:** [@Popeye](https://discourse.julialang.org/u/Popeye)\
**Replies:** 2\
**Last updated:** [March 24, 2022, 5:39pm UTC](https://discourse.julialang.org/t/equivalent-of-old-syntax-constraintref/78315 "2022-03-24T17:39:43Z")

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I came across @constraintref macro which was available in older versions of JuMP to generate constraints in a loop. This was removed in latest releases. How could I perform the same functionality in the latest version of…

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## [How to avoid function name conflict without using the package identifier every time](https://discourse.julialang.org/t/how-to-avoid-function-name-conflict-without-using-the-package-identifier-every-time/78186)

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**Author:** [@rubaiyat](https://discourse.julialang.org/u/rubaiyat)\
**Replies:** 10\
**Last updated:** [March 24, 2022, 5:32pm UTC](https://discourse.julialang.org/t/how-to-avoid-function-name-conflict-without-using-the-package-identifier-every-time/78186 "2022-03-24T17:32:14Z")

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Hello everyone, I was wondering if there was a way to avoid conflicts with a function name between packages without using the package identifier every time. To explain what I mean, when I write the following: using Dat…

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## [Evaluating a local function within the global namespace](https://discourse.julialang.org/t/evaluating-a-local-function-within-the-global-namespace/78403)

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**Author:** [@Niall](https://discourse.julialang.org/u/Niall)\
**Replies:** 5\
**Last updated:** [March 24, 2022, 4:59pm UTC](https://discourse.julialang.org/t/evaluating-a-local-function-within-the-global-namespace/78403 "2022-03-24T16:59:39Z")

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Hi. I’ve written a tutoral program in which students submit an answer ans to an exercise using the format reply(ans). reply then passes ans deeper into a module within which ans is tested for correctness. The thing is, t…

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## [\[ANN\] SimSearchManifoldLearning.jl: Non-linear dimensional reduction using SimilaritySearch (ManifoldLearning and UMAP)](https://discourse.julialang.org/t/ann-simsearchmanifoldlearning-jl-non-linear-dimensional-reduction-using-similaritysearch-manifoldlearning-and-umap/78416)

<div class="topic-metadata">

**Author:** [@Eric\_Sadit\_Tellez](https://discourse.julialang.org/u/Eric_Sadit_Tellez)\
**Replies:** 0\
**Last updated:** [March 24, 2022, 4:38pm UTC](https://discourse.julialang.org/t/ann-simsearchmanifoldlearning-jl-non-linear-dimensional-reduction-using-similaritysearch-manifoldlearning-and-umap/78416 "2022-03-24T16:38:33Z")

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I am glad to announce SimSearchManifoldLearning, which implements some methods and API to use SimilaritySearch with manifold learning methods. In particular, it implements the knn function for ManifoldLearning and relate…

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## [A function for iterables like Clojure's reductions](https://discourse.julialang.org/t/a-function-for-iterables-like-clojures-reductions/78407)

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**Author:** [@bwanab](https://discourse.julialang.org/u/bwanab)\
**Replies:** 2\
**Last updated:** [March 24, 2022, 4:23pm UTC](https://discourse.julialang.org/t/a-function-for-iterables-like-clojures-reductions/78407 "2022-03-24T16:23:12Z")

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I’ve searched, believe me, but every language calls it something different. In Clojure, it’s reductions, in APL it’s . It works like reduce, but where reduce reduces to one value, it returns all the intermediate values l…

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