# Latest

**URL:** https://discourse.julialang.org/latest.md?page=864

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

**Page:** 865

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## [Performance: Fast way to access numbers in Dataframes or alternatives](https://discourse.julialang.org/t/performance-fast-way-to-access-numbers-in-dataframes-or-alternatives/89884)

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**Author:** [@pjuergens](https://discourse.julialang.org/u/pjuergens)\
**Replies:** 12\
**Last updated:** [November 15, 2022, 9:35am UTC](https://discourse.julialang.org/t/performance-fast-way-to-access-numbers-in-dataframes-or-alternatives/89884 "2022-11-15T09:35:43Z")

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Hello together, I’m searching for a fast (or the fastest) way to access datapoints/numbers in a dataframes-like structure. I have 57 timeseries (columns) with 43800 datapoints (rows) each that are read in from a csv-fil…

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## [Lagragian multipliers in JuMP](https://discourse.julialang.org/t/lagragian-multipliers-in-jump/90234)

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**Author:** [@this\_josh](https://discourse.julialang.org/u/this_josh)\
**Replies:** 6\
**Last updated:** [November 15, 2022, 8:58am UTC](https://discourse.julialang.org/t/lagragian-multipliers-in-jump/90234 "2022-11-15T08:58:47Z")

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I appreciate questions about Lagrange multipliers in Jump have been discussed before, here the sign change is described. However, I’m having trouble reproducing example 6.32 (page 163) in Nonlinear and mixed-integer opti…

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## [MPI.API.MPI\_Reduce\_scatter ERRORS](https://discourse.julialang.org/t/mpi-api-mpi-reduce-scatter-errors/90093)

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**Author:** [@Neo](https://discourse.julialang.org/u/Neo)\
**Replies:** 7\
**Last updated:** [November 15, 2022, 6:09am UTC](https://discourse.julialang.org/t/mpi-api-mpi-reduce-scatter-errors/90093 "2022-11-15T06:09:09Z")

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From low-level API in MPI.jl, we know MPI.API.MPI\_Reduce\_scatter(sendbuf, recvbuf, recvcounts, datatype, op, comm) When I ran the code below with mpiexecjl -n 3 julia testReduce\_scatter.jl: # testReduce\_scatter.jl usi…

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## [DataFrame how to \`groupby\` then index with unspecified keys (merge them)](https://discourse.julialang.org/t/dataframe-how-to-groupby-then-index-with-unspecified-keys-merge-them/90248)

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**Author:** [@jling](https://discourse.julialang.org/u/jling)\
**Replies:** 12\
**Last updated:** [November 15, 2022, 3:59am UTC](https://discourse.julialang.org/t/dataframe-how-to-groupby-then-index-with-unspecified-keys-merge-them/90248 "2022-11-15T03:59:22Z")

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gdf = groupby(df, \[:gender, :nationality, :hair\_color\]); we know we can gdf\[(; gender = :X, natiaonlity = :US, hair\_color=:blue)\] to get a specific subdataframe, but this doesn’t work: gdf\[(; gender = :X, natiaonlity =…

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## [Type aggregation](https://discourse.julialang.org/t/type-aggregation/90270)

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**Author:** [@Brian1](https://discourse.julialang.org/u/Brian1)\
**Replies:** 2\
**Last updated:** [November 15, 2022, 3:12am UTC](https://discourse.julialang.org/t/type-aggregation/90270 "2022-11-15T03:12:26Z")

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I have these structs: struct A{T} n::T end struct B{T,N} n::T m::N end C{K} = B{T,N} where {T,N\<:A{K}} where {K} a1 = A(1) a2 = A(1.0); Then I construct a Vector: vec1 = \[B(1, a1), B(1, a1)\] 2-element …

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## [Suppressing location information for @info in Jupyter notebook](https://discourse.julialang.org/t/suppressing-location-information-for-info-in-jupyter-notebook/90260)

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**Author:** [@Shuvomoy\_Das\_Gupta](https://discourse.julialang.org/u/Shuvomoy_Das_Gupta)\
**Replies:** 2\
**Last updated:** [November 15, 2022, 2:46am UTC](https://discourse.julialang.org/t/suppressing-location-information-for-info-in-jupyter-notebook/90260 "2022-11-15T02:46:27Z")

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Dear All, Is there a way to suppress the location information for @info in Jupyter notebook? For example, if I type the following in a Jupyter notebook cell @info "hello world" and execute the cell, then the output in…

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## [Create non-linear structure in higher dimensional space](https://discourse.julialang.org/t/create-non-linear-structure-in-higher-dimensional-space/90204)

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**Author:** [@JosieG](https://discourse.julialang.org/u/JosieG)\
**Replies:** 17\
**Last updated:** [November 14, 2022, 11:52pm UTC](https://discourse.julialang.org/t/create-non-linear-structure-in-higher-dimensional-space/90204 "2022-11-14T23:52:03Z")

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Suppose I’m creating a non-linear structure in a 20-dim space. Right now I have a vector m = rand(1) vector = \[cos(m),sin(m),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1),rand(1…

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## [What is the difference (interpretation) between the partial R^2 and the SHAP value for a linear regression model?](https://discourse.julialang.org/t/what-is-the-difference-interpretation-between-the-partial-r-2-and-the-shap-value-for-a-linear-regression-model/90265)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 0\
**Last updated:** [November 14, 2022, 11:27pm UTC](https://discourse.julialang.org/t/what-is-the-difference-interpretation-between-the-partial-r-2-and-the-shap-value-for-a-linear-regression-model/90265 "2022-11-14T23:27:31Z")

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Both calculate the contribution of a given variable to the output’s variability but… To calculate the coefficient of partial determination R2 for a given variable: We calculate the R2 with and without that variable and…

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## [Regression with categorical variables. Reference porevious levels. Dummy](https://discourse.julialang.org/t/regression-with-categorical-variables-reference-porevious-levels-dummy/90194)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 5\
**Last updated:** [November 14, 2022, 11:08pm UTC](https://discourse.julialang.org/t/regression-with-categorical-variables-reference-porevious-levels-dummy/90194 "2022-11-14T23:08:49Z")

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Hello. If a do a linear regression model I can include the year as a categorical variable (instead of numerical) in order to estimate a different coefficient for each year. This is commonly done when the variable is not…

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## [Should I believe this Core.Box()?](https://discourse.julialang.org/t/should-i-believe-this-core-box/90263)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 10:55pm UTC](https://discourse.julialang.org/t/should-i-believe-this-core-box/90263 "2022-11-14T22:55:05Z")

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In a debug session. Note that D3\_ becomes instantly a Core.Box() but the precedent line, which is virtually equal, gets assigned as expected.

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## [How to convert a string to ISO-standard datetime?](https://discourse.julialang.org/t/how-to-convert-a-string-to-iso-standard-datetime/90261)

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**Author:** [@Hugo](https://discourse.julialang.org/u/Hugo)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 10:33pm UTC](https://discourse.julialang.org/t/how-to-convert-a-string-to-iso-standard-datetime/90261 "2022-11-14T22:33:23Z")

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I have a DataFrame with a column filled with type string for date and time. The strings are formatted as "2017-01-01 00:00:00+00:00", for instance. Searching online I found that this format is the ISO-standard for date a…

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## [DEV version slower again](https://discourse.julialang.org/t/dev-version-slower-again/90256)

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**Author:** [@joa-quim](https://discourse.julialang.org/u/joa-quim)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 10:14pm UTC](https://discourse.julialang.org/t/dev-version-slower-again/90256 "2022-11-14T22:14:26Z")

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This had happen with v1.8 but v1.9DEV had recovered … until a few day ago (my latest faster 1.9DEV was about 20 days old). Now :cry: | | |\_| | | | (\_| | | Version 1.7.0 (2021-11-30) \_/ |\\\_\_'\_|\_|\_|\\\_\_'\_| | Offici…

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## [Dependency Error :'(](https://discourse.julialang.org/t/dependency-error/90262)

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**Author:** [@chelseas](https://discourse.julialang.org/u/chelseas)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 10:05pm UTC](https://discourse.julialang.org/t/dependency-error/90262 "2022-11-14T22:05:14Z")

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I am getting this error from my use of BlockDiagonals: ERROR: Unsatisfiable requirements detected for package BlockDiagonals \[0a1fb500\]: BlockDiagonals \[0a1fb500\] log: ├─BlockDiagonals \[0a1fb500\] has no known versions…

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## [Julia nightly is 27 days old](https://discourse.julialang.org/t/julia-nightly-is-27-days-old/90054)

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**Author:** [@gitboy16](https://discourse.julialang.org/u/gitboy16)\
**Replies:** 7\
**Last updated:** [November 14, 2022, 10:01pm UTC](https://discourse.julialang.org/t/julia-nightly-is-27-days-old/90054 "2022-11-14T22:01:23Z")

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Hi, Are there currently issues with the nightly Julia build (windows)? If yes, where can I see the issue affecting the build process? Thank you Kind regards

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## [Proper use of MDS and PCA](https://discourse.julialang.org/t/proper-use-of-mds-and-pca/90257)

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**Author:** [@JosieG](https://discourse.julialang.org/u/JosieG)\
**Replies:** 4\
**Last updated:** [November 14, 2022, 9:40pm UTC](https://discourse.julialang.org/t/proper-use-of-mds-and-pca/90257 "2022-11-14T21:40:49Z")

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Assume I have a 20\*85 matrix. Here is my code M = fit(PCA, matrix; maxoutdim=2) Yte = predict(M, matrix) M1 = fit(MDS, matrix; maxoutdim=2, distances=false) Yte1 = predict(M1) My Yte and Yte1 are identicall…

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## [Recording an MCMC Chain](https://discourse.julialang.org/t/recording-an-mcmc-chain/90243)

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**Author:** [@clinton](https://discourse.julialang.org/u/clinton)\
**Replies:** 9\
**Last updated:** [November 14, 2022, 9:35pm UTC](https://discourse.julialang.org/t/recording-an-mcmc-chain/90243 "2022-11-14T21:35:15Z")

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I’ve written my own MCMC code. MCMCChains provides some helper functions wrt working with already completed chains. As I iterate through the chain, what is the best way to store the each pass? E.g., if I complete non-bu…

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## [UndefVarError: transform not defined](https://discourse.julialang.org/t/undefvarerror-transform-not-defined/90259)

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**Author:** [@JosieG](https://discourse.julialang.org/u/JosieG)\
**Replies:** 1\
**Last updated:** [November 14, 2022, 9:27pm UTC](https://discourse.julialang.org/t/undefvarerror-transform-not-defined/90259 "2022-11-14T21:27:50Z")

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I got this error and my code is using MultivariateStats, RDatasets, Plots # load iris dataset iris = dataset("datasets", "iris") # take half of the dataset X = Matrix(iris\[1:2:end,1:4\])' X\_labels = Vector(iris\[1:2:end…

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## [Splitting kwargs into specific keyword arguments?](https://discourse.julialang.org/t/splitting-kwargs-into-specific-keyword-arguments/90131)

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**Author:** [@TTolppanen](https://discourse.julialang.org/u/TTolppanen)\
**Replies:** 10\
**Last updated:** [November 14, 2022, 9:24pm UTC](https://discourse.julialang.org/t/splitting-kwargs-into-specific-keyword-arguments/90131 "2022-11-14T21:24:54Z")

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Let’s say I have these two functions: function funA(; a=2.0) #something end function funB(; b=4.0) #something end They both take keywords arguments with default values. Now if I want to use these in a third fu…

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## [Replacing strings in specific position indices as in \`str\_sub()\` in \`stringr\`](https://discourse.julialang.org/t/replacing-strings-in-specific-position-indices-as-in-str-sub-in-stringr/90187)

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**Author:** [@Alex\_Tantos](https://discourse.julialang.org/u/Alex_Tantos)\
**Replies:** 9\
**Last updated:** [November 14, 2022, 7:39pm UTC](https://discourse.julialang.org/t/replacing-strings-in-specific-position-indices-as-in-str-sub-in-stringr/90187 "2022-11-14T19:39:24Z")

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Hi. I am tring to duplicate the functionality of the R package stringr in Julia so that I prepare a cheatsheet for string manipulation in Julia. Particularly, I am thinking of how to achieve str\_sub()'s output in Julia.…

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## [Should there be a Chemistry Domain/Organization?](https://discourse.julialang.org/t/should-there-be-a-chemistry-domain-organization/36475)

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**Author:** [@anon92994695](https://discourse.julialang.org/u/anon92994695)\
**Replies:** 30\
**Last updated:** [November 14, 2022, 7:44pm UTC](https://discourse.julialang.org/t/should-there-be-a-chemistry-domain-organization/36475 "2022-11-14T19:44:56Z")

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Should there be a chemistry domain/organization? I think this would have very few users… But, there are a few packages of this nature (maybe 5-6 now?). I am a chemist by training so this interests me, but I don’t know i…

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## [What is the future of StatsModels.jl](https://discourse.julialang.org/t/what-is-the-future-of-statsmodels-jl/90255)

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**Author:** [@PharmCat](https://discourse.julialang.org/u/PharmCat)\
**Replies:** 0\
**Last updated:** [November 14, 2022, 6:47pm UTC](https://discourse.julialang.org/t/what-is-the-future-of-statsmodels-jl/90255 "2022-11-14T18:47:21Z")

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Hi! I am afraid, that more than year there was no significant commits into StatsModels.jl. As I understand devs are planning to remake FunctionTerm and some other less sensitive things. So I try to understand what is rea…

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## [Installation clobbers LDFLAGS](https://discourse.julialang.org/t/installation-clobbers-ldflags/90139)

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**Author:** [@smartalecH](https://discourse.julialang.org/u/smartalecH)\
**Replies:** 3\
**Last updated:** [November 14, 2022, 5:27pm UTC](https://discourse.julialang.org/t/installation-clobbers-ldflags/90139 "2022-11-14T17:27:36Z")

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I’m trying to build Julia on some complicated infra with rather strict tooling. I’m trying to do things the “right way” and build all of the listed dependencies (i.e. no system dependency flags). When I get to the part …

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## [Is calling \`x = @spawn f(x)\` a bad idea?](https://discourse.julialang.org/t/is-calling-x-spawn-f-x-a-bad-idea/89934)

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**Author:** [@artemsolod](https://discourse.julialang.org/u/artemsolod)\
**Replies:** 5\
**Last updated:** [November 14, 2022, 4:22pm UTC](https://discourse.julialang.org/t/is-calling-x-spawn-f-x-a-bad-idea/89934 "2022-11-14T16:22:24Z")

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I am a bit unclear on how and when variables are captured in @spawn call. For instance, the following errors julia\> using Base.Threads julia\> let x = 1 x = @spawn x + 3 fetch(x) end ERROR: …

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## [A Kerchunk-like package for Julia](https://discourse.julialang.org/t/a-kerchunk-like-package-for-julia/89996)

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**Author:** [@alex-s-gardner](https://discourse.julialang.org/u/alex-s-gardner)\
**Replies:** 10\
**Last updated:** [November 14, 2022, 4:08pm UTC](https://discourse.julialang.org/t/a-kerchunk-like-package-for-julia/89996 "2022-11-14T16:08:32Z")

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Does anyone know if there is a Kerchunk-like package for Julia or if there is any work towards such a package? Kerchunk for Julia would be immensely useful.

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## [Equal method to matlab unique in rows](https://discourse.julialang.org/t/equal-method-to-matlab-unique-in-rows/90240)

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**Author:** [@Bozaga\_Murat](https://discourse.julialang.org/u/Bozaga_Murat)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 3:37pm UTC](https://discourse.julialang.org/t/equal-method-to-matlab-unique-in-rows/90240 "2022-11-14T15:37:05Z")

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Hello everyboday, I not found the equal method “unique(x,‘rows’)” in Julia to matlab. Does it know anybody ? Thanks.

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## [Constructor with type parameters and keywords](https://discourse.julialang.org/t/constructor-with-type-parameters-and-keywords/90244)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 0\
**Last updated:** [November 14, 2022, 3:30pm UTC](https://discourse.julialang.org/t/constructor-with-type-parameters-and-keywords/90244 "2022-11-14T15:30:07Z")

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Suppose I have a constructor with some type parameters that do not correspond to fields, which I would like to determine automatically, in addition to getting the rest from keywords. Eg Base.@kwdef struct Foo{K,T} x…

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## [How to consider the timezone in unix2datetime?](https://discourse.julialang.org/t/how-to-consider-the-timezone-in-unix2datetime/90179)

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**Author:** [@marllos](https://discourse.julialang.org/u/marllos)\
**Replies:** 9\
**Last updated:** [November 14, 2022, 2:49pm UTC](https://discourse.julialang.org/t/how-to-consider-the-timezone-in-unix2datetime/90179 "2022-11-14T14:49:17Z")

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Hello everyone. In the code below my time zone is not being considered in dt. Please, how to make it be considered? using Dates function test() f = "local/file" u = mtime(f) unix2datetime(u) # three hours too long …

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## [Threads (including Polyester) question](https://discourse.julialang.org/t/threads-including-polyester-question/90233)

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**Author:** [@Palli](https://discourse.julialang.org/u/Palli)\
**Replies:** 1\
**Last updated:** [November 14, 2022, 1:10pm UTC](https://discourse.julialang.org/t/threads-including-polyester-question/90233 "2022-11-14T13:10:15Z")

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I get worse timing with threads (in the best case), and also different values, not pi, or at best if I’m lucky. I had already sped that benchmark up more than 5x, and curious if threading in some form could make even bet…

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## [ERROR: expected package \`CSV\` to exist in the manifest](https://discourse.julialang.org/t/error-expected-package-csv-to-exist-in-the-manifest/90227)

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**Author:** [@clarakoehne](https://discourse.julialang.org/u/clarakoehne)\
**Replies:** 2\
**Last updated:** [November 14, 2022, 2:27pm UTC](https://discourse.julialang.org/t/error-expected-package-csv-to-exist-in-the-manifest/90227 "2022-11-14T14:27:20Z")

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Hello everyone! I am getting a very strange error when I try to run my Julia program. It looks as follows: ERROR: expected package \`CSV \[336ed68f\]\` to exist in the manifest (use \`resolve\` to populate the manifest) Stack…

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## [Metaprogramming: Defining new methods to existing function](https://discourse.julialang.org/t/metaprogramming-defining-new-methods-to-existing-function/90239)

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**Author:** [@HashBrown](https://discourse.julialang.org/u/HashBrown)\
**Replies:** 0\
**Last updated:** [November 14, 2022, 2:24pm UTC](https://discourse.julialang.org/t/metaprogramming-defining-new-methods-to-existing-function/90239 "2022-11-14T14:24:15Z")

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I want to create a macro that adds methods to a function for particular types and creates some global variables (I know not the best practice but this is what I am trying). It is not difficult for me to do this if the m…

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