# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1798

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

**Page:** 1799

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## [Julia Database or CSV filtering](https://discourse.julialang.org/t/julia-database-or-csv-filtering/36104)

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**Author:** [@bandaya](https://discourse.julialang.org/u/bandaya)\
**Replies:** 8\
**Last updated:** [March 18, 2020, 12:47pm UTC](https://discourse.julialang.org/t/julia-database-or-csv-filtering/36104 "2020-03-18T12:47:06Z")

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Hi, I am using JuliaDB.jl package to upload CSV files but having problems with filtering or extracting some data. using JuliaDB # t = loadtable("MTab.csv") # Assume that the CSV contains the following data t = table(\[1,…

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## [Optimisation design advice - metaprogramming/closures](https://discourse.julialang.org/t/optimisation-design-advice-metaprogramming-closures/35264)

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**Author:** [@anon32405968](https://discourse.julialang.org/u/anon32405968)\
**Replies:** 6\
**Last updated:** [March 18, 2020, 11:57am UTC](https://discourse.julialang.org/t/optimisation-design-advice-metaprogramming-closures/35264 "2020-03-18T11:57:38Z")

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Hello. We are trying to optimise parameters for functions that look something like: function cost\_func(time::Vector{Float64}, params::Vector{Float64}) cₐ, a, cᵦ, β = params return (some complicated combination o…

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## [How to install package dependencies for unregistered package](https://discourse.julialang.org/t/how-to-install-package-dependencies-for-unregistered-package/36088)

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**Author:** [@sloede](https://discourse.julialang.org/u/sloede)\
**Replies:** 20\
**Last updated:** [March 18, 2020, 11:01am UTC](https://discourse.julialang.org/t/how-to-install-package-dependencies-for-unregistered-package/36088 "2020-03-18T11:01:27Z")

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I have created a few packages for numerical simulations, which are not (yet) registered anywhere. My current development workflow is to just clone the repository manually and to use a script to start the simulations (whi…

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## [Creating one column from multiple DataFrames](https://discourse.julialang.org/t/creating-one-column-from-multiple-dataframes/36107)

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**Author:** [@danielw2904](https://discourse.julialang.org/u/danielw2904)\
**Replies:** 3\
**Last updated:** [March 18, 2020, 10:38am UTC](https://discourse.julialang.org/t/creating-one-column-from-multiple-dataframes/36107 "2020-03-18T10:38:17Z")

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I have a data similar to the following in which one column is partly defined in one DataFrame and partly in a second using DataFrames, DataFramesMeta # Data situation: df1 = DataFrame(id1 = \[1, 2, 3, 4\], id2 = \[missing,…

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## [Documentation without package creation](https://discourse.julialang.org/t/documentation-without-package-creation/36133)

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**Author:** [@Sebastian\_Troue](https://discourse.julialang.org/u/Sebastian_Troue)\
**Replies:** 0\
**Last updated:** [March 18, 2020, 10:24am UTC](https://discourse.julialang.org/t/documentation-without-package-creation/36133 "2020-03-18T10:24:55Z")

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Is it possible to create a html page containg the Doc-Strings of all .jl files inside a folder (and subfolders)? I do not want to create a package or module out of the files. I just want a well organized overview over al…

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## [Catching tuples with types in them](https://discourse.julialang.org/t/catching-tuples-with-types-in-them/36078)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 5\
**Last updated:** [March 18, 2020, 10:16am UTC](https://discourse.julialang.org/t/catching-tuples-with-types-in-them/36078 "2020-03-18T10:16:05Z")

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I’m trying to dispatch a method acting on tuples where one of the elements is a type and ran into difficulties because of some unexpected behaviour. First, here’s behaviour I thought I understood: julia\> (:x, 4) isa Tu…

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## [Vector with elements of specified type?](https://discourse.julialang.org/t/vector-with-elements-of-specified-type/36118)

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**Author:** [@BLI](https://discourse.julialang.org/u/BLI)\
**Replies:** 5\
**Last updated:** [March 18, 2020, 9:45am UTC](https://discourse.julialang.org/t/vector-with-elements-of-specified-type/36118 "2020-03-18T09:45:45Z")

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Ideally, I’d like to create a container vector v of 10 elements, where each element of v is a vector of length 3, holding Float64 numbers (undefined value at the outset). After this, I’d like to fill in vectors with valu…

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## [Interactive Plotting Won't turn off](https://discourse.julialang.org/t/interactive-plotting-wont-turn-off/36130)

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**Author:** [@astroboy](https://discourse.julialang.org/u/astroboy)\
**Replies:** 1\
**Last updated:** [March 18, 2020, 8:05am UTC](https://discourse.julialang.org/t/interactive-plotting-wont-turn-off/36130 "2020-03-18T08:05:31Z")

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Hi guys, hope you’re all doing well! I’m having a problem with turning interactive plotting off in Jupyter. I’ve included the packages/import statement and the plotting cell below: using PyPlot PyPlot.pygui(false) PyPl…

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## [Developed package "shadows" dependency package](https://discourse.julialang.org/t/developed-package-shadows-dependency-package/36017)

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**Author:** [@cserteGT3](https://discourse.julialang.org/u/cserteGT3)\
**Replies:** 8\
**Last updated:** [March 18, 2020, 7:34am UTC](https://discourse.julialang.org/t/developed-package-shadows-dependency-package/36017 "2020-03-18T07:34:03Z")

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I’m not sure how to formulate this question/issue, I try to be as straightforward as possible. So I have two packages developed by myself (both are public, hosted on github). I started developing PackageA and at some po…

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## [Writedlm - adding a blank line every n lines](https://discourse.julialang.org/t/writedlm-adding-a-blank-line-every-n-lines/36111)

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**Author:** [@razvangheorghe](https://discourse.julialang.org/u/razvangheorghe)\
**Replies:** 3\
**Last updated:** [March 18, 2020, 7:21am UTC](https://discourse.julialang.org/t/writedlm-adding-a-blank-line-every-n-lines/36111 "2020-03-18T07:21:45Z")

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Hi, I have three columns of numbers. x and y are coordinates and z is the value at x and y. I’m currently saving them to files like this: open(path, "w") do io writedlm(io, \[x y z\]) end I’m trying to splot as a pm…

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## [Ccall fails on \*\*arrays of ComplexF64 (simple MWE)](https://discourse.julialang.org/t/ccall-fails-on-arrays-of-complexf64-simple-mwe/36127)

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**Author:** [@xzackli](https://discourse.julialang.org/u/xzackli)\
**Replies:** 1\
**Last updated:** [March 18, 2020, 3:45am UTC](https://discourse.julialang.org/t/ccall-fails-on-arrays-of-complexf64-simple-mwe/36127 "2020-03-18T03:45:57Z")

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I’m trying to modify 2D arrays using ccall, and this fails when the arrays contain complex double. The same code works when restricted to double. MWE Consider a C function which copies a 2D real array into a complex ar…

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## [Why does LightGraphs.katz\_centrality give negative centrality scores?](https://discourse.julialang.org/t/why-does-lightgraphs-katz-centrality-give-negative-centrality-scores/21204)

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**Author:** [@ennvvy](https://discourse.julialang.org/u/ennvvy)\
**Replies:** 1\
**Last updated:** [March 18, 2020, 3:40am UTC](https://discourse.julialang.org/t/why-does-lightgraphs-katz-centrality-give-negative-centrality-scores/21204 "2020-03-18T03:40:29Z")

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I am using Katz\_centrality to determine the centrality measures for nodes in the network Julia 1.1.0. However, it yields negative values. Shouldn’t centrality scores be positive ?

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## [Exporting Julia code as HTML or PDF](https://discourse.julialang.org/t/exporting-julia-code-as-html-or-pdf/35340)

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**Author:** [@brett\_knoss](https://discourse.julialang.org/u/brett_knoss)\
**Replies:** 26\
**Last updated:** [March 18, 2020, 12:37am UTC](https://discourse.julialang.org/t/exporting-julia-code-as-html-or-pdf/35340 "2020-03-18T00:37:23Z")

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How do I export my .jl program as an HTML or PDF for a report?

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## [Unexpected dimension mismatch when using read!(io, BitArray)](https://discourse.julialang.org/t/unexpected-dimension-mismatch-when-using-read-io-bitarray/3036)

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**Author:** [@sekunder](https://discourse.julialang.org/u/sekunder)\
**Replies:** 4\
**Last updated:** [March 17, 2020, 11:32pm UTC](https://discourse.julialang.org/t/unexpected-dimension-mismatch-when-using-read-io-bitarray/3036 "2020-03-17T23:32:10Z")

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I am running into a strange DimensionMismatch error when using read! to fill a BitArray. The offending lines look like this: frames = BitArray(N\_bits\_per\_frame, N\_frames) read!(joinpath(root\_dir, bin\_file), frames) The…

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## [Filtering DataFrame on String](https://discourse.julialang.org/t/filtering-dataframe-on-string/36117)

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**Author:** [@johnh](https://discourse.julialang.org/u/johnh)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 10:56pm UTC](https://discourse.julialang.org/t/filtering-dataframe-on-string/36117 "2020-03-17T22:56:30Z")

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Gahhhh… I show my ignorance. I have searched here and cannot quite get the answer. In the Kaggle covid-19 dataset I read covid\_19\_data.csv into a DataFrame The columns are: julia\> names(df) 8-element Array{Symbol,1}: …

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## [How to retrieve Char in C](https://discourse.julialang.org/t/how-to-retrieve-char-in-c/36057)

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**Author:** [@nnn](https://discourse.julialang.org/u/nnn)\
**Replies:** 5\
**Last updated:** [March 17, 2020, 10:44pm UTC](https://discourse.julialang.org/t/how-to-retrieve-char-in-c/36057 "2020-03-17T22:44:39Z")

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I need to get value from Julia Char datatype into C. As I understand Char is implemented here and comment says: Char is a 32-bit AbstractChar type that is the default representation of characters in Julia. Char is the…

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## [Invitation to VizCon 2 - 12-16 March 2020](https://discourse.julialang.org/t/invitation-to-vizcon-2-12-16-march-2020/33806)

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**Author:** [@mkborregaard](https://discourse.julialang.org/u/mkborregaard)\
**Replies:** 48\
**Last updated:** [March 17, 2020, 10:31pm UTC](https://discourse.julialang.org/t/invitation-to-vizcon-2-12-16-march-2020/33806 "2020-03-17T22:31:07Z")

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Dear everyone, In case you haven’t seen the announcements on Slack, this is an invitation to join the second Julia VizCon in Berlin 12-16 March this year. The VizCon is a working meeting for anyone wanting to contribute…

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## [On the garbage collection](https://discourse.julialang.org/t/on-the-garbage-collection/35695)

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**Author:** [@bicycle1885](https://discourse.julialang.org/u/bicycle1885)\
**Replies:** 35\
**Last updated:** [March 17, 2020, 8:43pm UTC](https://discourse.julialang.org/t/on-the-garbage-collection/35695 "2020-03-17T20:43:20Z")

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Hi, I still feel some difficulty in understanding garbage collection. My understanding is that Julia has the mark-and-sweep garbage collector, which marks a set of GC-rooted objects and other objects traceable (or reach…

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## [ABI compatibility between versions](https://discourse.julialang.org/t/abi-compatibility-between-versions/36110)

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**Author:** [@nnn](https://discourse.julialang.org/u/nnn)\
**Replies:** 0\
**Last updated:** [March 17, 2020, 7:35pm UTC](https://discourse.julialang.org/t/abi-compatibility-between-versions/36110 "2020-03-17T19:35:39Z")

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I’m building a C shared library for the current stable release: v1.3.1 using Julia C API. With new Julia versions in the future would I need to rebuild my library for new Julia versions or are they ABI compatible? I’m …

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## [Segfault on DataFrames \`getindex\`](https://discourse.julialang.org/t/segfault-on-dataframes-getindex/20612)

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**Author:** [@Rory-Finnegan](https://discourse.julialang.org/u/Rory-Finnegan)\
**Replies:** 24\
**Last updated:** [February 12, 2019, 9:13am UTC](https://discourse.julialang.org/t/segfault-on-dataframes-getindex/20612 "2019-02-12T09:13:30Z")

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Hi folks, We’re getting a somewhat random segfault on a dataframes getindex operation inside a for-loop. I haven’t been able to extract a MWE from the proprietary code where this is occurring, but here is part of the se…

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## [JuMPv0.21 and deepcopy](https://discourse.julialang.org/t/jumpv0-21-and-deepcopy/36051)

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**Author:** [@dmetivie](https://discourse.julialang.org/u/dmetivie)\
**Replies:** 7\
**Last updated:** [March 17, 2020, 5:03pm UTC](https://discourse.julialang.org/t/jumpv0-21-and-deepcopy/36051 "2020-03-17T17:03:17Z")

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Hi, In JuMP Version 0.21 it says Calling deepcopy(::AbstractModel) now throws an error. Is there a new way to do deepcopy()? As far as I understand copy() is not what I want because the copied and original model are…

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## [DSP.jl Resampled signal length doesn't match upsampling factor](https://discourse.julialang.org/t/dsp-jl-resampled-signal-length-doesnt-match-upsampling-factor/36036)

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**Author:** [@meritwagner](https://discourse.julialang.org/u/meritwagner)\
**Replies:** 3\
**Last updated:** [March 17, 2020, 4:50pm UTC](https://discourse.julialang.org/t/dsp-jl-resampled-signal-length-doesnt-match-upsampling-factor/36036 "2020-03-17T16:50:31Z")

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Hey guys, I ran into a problem, while trying out the resampling algorithm from the DSP package (v0.6.3). First I just create a test array with random numbers between 1 and 2. My plan is then to resample up by factor of…

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## [Package removed from pkg.julialang.org?](https://discourse.julialang.org/t/package-removed-from-pkg-julialang-org/35590)

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**Author:** [@chakravala](https://discourse.julialang.org/u/chakravala)\
**Replies:** 16\
**Last updated:** [March 17, 2020, 4:17pm UTC](https://discourse.julialang.org/t/package-removed-from-pkg-julialang-org/35590 "2020-03-17T16:17:08Z")

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For some reason, my Grassmann.jl package was removed from the pkg.julialang.org website. Don’t know where I can file a github issue about this, so I opened this thread instad.

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## [Change colors in Julia-Client](https://discourse.julialang.org/t/change-colors-in-julia-client/36103)

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**Author:** [@erlebach](https://discourse.julialang.org/u/erlebach)\
**Replies:** 1\
**Last updated:** [March 17, 2020, 3:59pm UTC](https://discourse.julialang.org/t/change-colors-in-julia-client/36103 "2020-03-17T15:59:01Z")

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I do not know whether this is the proper place for this issue. I would like to: change the color of comments in Julia source (within terminal windows/panels in Atom). change the color of the top menu bar to something …

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## [How to call nonlinear solver in MathOptInterface](https://discourse.julialang.org/t/how-to-call-nonlinear-solver-in-mathoptinterface/36001)

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**Author:** [@zxjroger](https://discourse.julialang.org/u/zxjroger)\
**Replies:** 3\
**Last updated:** [March 17, 2020, 3:06pm UTC](https://discourse.julialang.org/t/how-to-call-nonlinear-solver-in-mathoptinterface/36001 "2020-03-17T15:06:53Z")

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I am trying to move from MathProgBase to MathOptInterface. My code works for the former package, but after I rewrote it using the latter package, I got an error saying Ipopt: Failed to construct problem. I believe it is …

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## [2-dimensional DataFrame column](https://discourse.julialang.org/t/2-dimensional-dataframe-column/36060)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 2\
**Last updated:** [March 17, 2020, 3:05pm UTC](https://discourse.julialang.org/t/2-dimensional-dataframe-column/36060 "2020-03-17T15:05:32Z")

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MATLAB-tables and pandas-dataframe enable more than one element per cell (column-row pair). Is the same possible in Julia DataFrames? I tried for example: julia\> df = DataFrame(A = ones(10), B = ones(10,2)) which promp…

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## [Coronavirus data set](https://discourse.julialang.org/t/coronavirus-data-set/36094)

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**Author:** [@mike\_k](https://discourse.julialang.org/u/mike_k)\
**Replies:** 0\
**Last updated:** [March 17, 2020, 12:42pm UTC](https://discourse.julialang.org/t/coronavirus-data-set/36094 "2020-03-17T12:42:06Z")

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Let me point you to a nice dataset in case you like to contribute whatever. Stay safe, and have fun :wink:

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## [Why length(str) != sizeof(str)?](https://discourse.julialang.org/t/why-length-str-sizeof-str/36068)

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**Author:** [@BMval](https://discourse.julialang.org/u/BMval)\
**Replies:** 21\
**Last updated:** [March 17, 2020, 1:37pm UTC](https://discourse.julialang.org/t/why-length-str-sizeof-str/36068 "2020-03-17T13:37:27Z")

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I used to use length() for string, but right now I noticed it’s not correct for big string, around 3000 characters. sizeof() give right result. Why is it? thank you in advance.

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## [How to start tasks on multiple threads and control terminal output from central thread](https://discourse.julialang.org/t/how-to-start-tasks-on-multiple-threads-and-control-terminal-output-from-central-thread/36087)

<div class="topic-metadata">

**Author:** [@sloede](https://discourse.julialang.org/u/sloede)\
**Replies:** 5\
**Last updated:** [March 17, 2020, 1:29pm UTC](https://discourse.julialang.org/t/how-to-start-tasks-on-multiple-threads-and-control-terminal-output-from-central-thread/36087 "2020-03-17T13:29:40Z")

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While I am not new to distributed computing, I have trouble wrapping my head around how to implement the following behavior in Julia. I have a testing tool that takes a bunch of tests (= directories with testing informa…

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## [Pair Programming/Julia Coding Live Stream](https://discourse.julialang.org/t/pair-programming-julia-coding-live-stream/25557)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 5\
**Last updated:** [March 17, 2020, 1:25pm UTC](https://discourse.julialang.org/t/pair-programming-julia-coding-live-stream/25557 "2020-03-17T13:25:52Z")

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I’m wondering if anyone is interested in joining me on Twitch for some live pair/mob programming sessions. I’d like to start a regularly recurring stream that will serve as a place for members of the Julia community to c…

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