# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1756

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

**Page:** 1757

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## [Difficulty figuring out when to use pmap, @sync, @async, @distributed](https://discourse.julialang.org/t/difficulty-figuring-out-when-to-use-pmap-sync-async-distributed/38794)

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**Author:** [@JedPhillips](https://discourse.julialang.org/u/JedPhillips)\
**Replies:** 1\
**Last updated:** [May 5, 2020, 2:54pm UTC](https://discourse.julialang.org/t/difficulty-figuring-out-when-to-use-pmap-sync-async-distributed/38794 "2020-05-05T14:54:26Z")

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I’m trying to optimize some code running in parallel. I’m struggling to figure out the best way to lay out this approach, and where to use pmap(), sync, async, distributed etc. I am applying a null model randomization t…

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## [Possible garbage collection interaction with Juno](https://discourse.julialang.org/t/possible-garbage-collection-interaction-with-juno/38780)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 2\
**Last updated:** [May 5, 2020, 2:41pm UTC](https://discourse.julialang.org/t/possible-garbage-collection-interaction-with-juno/38780 "2020-05-05T14:41:04Z")

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Hi, I’m trying to figure out what’s happening here. Running the following example: using DifferentialEquations, Plots function usode!(du,u,p,t) C1 = 1.63e-9 RS = 791.0 C2 = 3.3e-9 C0 = 0.3e-9 L1 =…

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## [PyPlot fails on Mac](https://discourse.julialang.org/t/pyplot-fails-on-mac/38774)

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**Author:** [@monty](https://discourse.julialang.org/u/monty)\
**Replies:** 3\
**Last updated:** [May 5, 2020, 1:57pm UTC](https://discourse.julialang.org/t/pyplot-fails-on-mac/38774 "2020-05-05T13:57:41Z")

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julia\> import PyPlot julia\> PyPlot.plot(rand(4)) 1-element Array{PyCall.PyObject,1}: PyObject \<matplotlib.lines.Line2D object at 0x7ff970b12da0\> julia\> PyPlot.savefig("a.png") ERROR: PyError ($(Expr(:escape, :(ccall(#…

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## [Counting all subtypes](https://discourse.julialang.org/t/counting-all-subtypes/38797)

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**Author:** [@br500](https://discourse.julialang.org/u/br500)\
**Replies:** 6\
**Last updated:** [May 5, 2020, 1:47pm UTC](https://discourse.julialang.org/t/counting-all-subtypes/38797 "2020-05-05T13:47:54Z")

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I’m trying to count all subtypes of given type (subtypes of these subtypes and so on) with a recursive function, but for now I only managed to write one showing the structure by creating arrays in arrays… function allSu…

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## [Nondeterministic results for subset sum using @threads](https://discourse.julialang.org/t/nondeterministic-results-for-subset-sum-using-threads/38808)

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**Author:** [@eaubanel](https://discourse.julialang.org/u/eaubanel)\
**Replies:** 3\
**Last updated:** [May 5, 2020, 1:37pm UTC](https://discourse.julialang.org/t/nondeterministic-results-for-subset-sum-using-threads/38808 "2020-05-05T13:37:40Z")

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I’ve encountered nondeterministic results for a naive subset sum implementation using @threads. This algorithm fills the dynamic programming table column by column from left to right. There’s one column for each integer …

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## [Multithreading cause segmentation error of deprecation warning](https://discourse.julialang.org/t/multithreading-cause-segmentation-error-of-deprecation-warning/38806)

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**Author:** [@JiangXL](https://discourse.julialang.org/u/JiangXL)\
**Replies:** 1\
**Last updated:** [May 5, 2020, 1:24pm UTC](https://discourse.julialang.org/t/multithreading-cause-segmentation-error-of-deprecation-warning/38806 "2020-05-05T13:24:29Z")

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Running following codes without --depwarn=no using Images img = rand(512,512); Threads.@threads for i in 1:200 edge,count=imhist(img) end causes Julia crash with different output, most useful should be: ┌ Err…

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## [Convince me to use Julia](https://discourse.julialang.org/t/convince-me-to-use-julia/38635)

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**Author:** [@dlsweet](https://discourse.julialang.org/u/dlsweet)\
**Replies:** 17\
**Last updated:** [May 5, 2020, 11:53am UTC](https://discourse.julialang.org/t/convince-me-to-use-julia/38635 "2020-05-05T11:53:40Z")

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Hey all, I’m a statistician and I’m pretty proficient in R and Python, I want to hear all of the reasons I should look into Julia.

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## [How to speed up creating a sparse matrix?](https://discourse.julialang.org/t/how-to-speed-up-creating-a-sparse-matrix/38800)

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**Author:** [@lesshaste](https://discourse.julialang.org/u/lesshaste)\
**Replies:** 2\
**Last updated:** [May 5, 2020, 11:43am UTC](https://discourse.julialang.org/t/how-to-speed-up-creating-a-sparse-matrix/38800 "2020-05-05T11:43:23Z")

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I am attempting to create a sparse matrix from an array of arrays called S . My code is this: function make\_matrix(nostates, S) M = spzeros(Int32, nostates, nostates) convert(SparseMatrixCSC{UInt32, UInt32}, M) …

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## [How to parse a long string when regex fails](https://discourse.julialang.org/t/how-to-parse-a-long-string-when-regex-fails/38558)

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**Author:** [@lesshaste](https://discourse.julialang.org/u/lesshaste)\
**Replies:** 9\
**Last updated:** [May 5, 2020, 11:23am UTC](https://discourse.julialang.org/t/how-to-parse-a-long-string-when-regex-fails/38558 "2020-05-05T11:23:10Z")

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I have strings like: Automaton(“det”,266,4,\[\[1, 127, 50, 50, 115, 249, 50, 8, 257, 10, 151, 12, 13, 14, 81, 78, 34, 106, 137, 107, 21, 22, 82, 89, 71, 43, 43, 62, 63, 63, 44, 10, 179, 171, 214, 265, 206, 38, 137, 152,…

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## [Macro for parallel out-of-order execution?](https://discourse.julialang.org/t/macro-for-parallel-out-of-order-execution/38706)

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**Author:** [@oschulz](https://discourse.julialang.org/u/oschulz)\
**Replies:** 7\
**Last updated:** [May 5, 2020, 10:46am UTC](https://discourse.julialang.org/t/macro-for-parallel-out-of-order-execution/38706 "2020-05-05T10:46:05Z")

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Do we have a macro in some package that turns something like this @parallel\_out\_of\_order begin a = foo() bar() b = baz() end into an equivalent of this future\_1 = Threads.@spawn foo() future\_2 = Th…

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## [Using MATLAB in Julia](https://discourse.julialang.org/t/using-matlab-in-julia/38790)

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**Author:** [@Ashwin\_Sundarka](https://discourse.julialang.org/u/Ashwin_Sundarka)\
**Replies:** 1\
**Last updated:** [May 5, 2020, 10:25am UTC](https://discourse.julialang.org/t/using-matlab-in-julia/38790 "2020-05-05T10:25:57Z")

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i have installed MATLAB and the package to my Julia as given in “https://github.com/JuliaInterop/MATLAB.jl” Now I am trying to run the example codes given here for a quick start. for example this code: x = range(-10.0…

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## [Preallocating array of matrices](https://discourse.julialang.org/t/preallocating-array-of-matrices/38665)

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**Author:** [@martincornejo](https://discourse.julialang.org/u/martincornejo)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 10:12am UTC](https://discourse.julialang.org/t/preallocating-array-of-matrices/38665 "2020-05-05T10:12:27Z")

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To preallocate an array of matrices we can write the following: A = Array{Matrix{Float64}}(undef, n) # n being the number of array elements (matrices) If we knew that each of the matrices in A has dimensions of 3 x 3,…

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## [Saving using DelimitedFiled with header](https://discourse.julialang.org/t/saving-using-delimitedfiled-with-header/38793)

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**Author:** [@Nash](https://discourse.julialang.org/u/Nash)\
**Replies:** 2\
**Last updated:** [May 5, 2020, 8:45am UTC](https://discourse.julialang.org/t/saving-using-delimitedfiled-with-header/38793 "2020-05-05T08:45:43Z")

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On StockOverflow, I noticed a simple example of saving data to a delimited file: x = \[1 2 ; 3 4\] header = \["a" "b"\] writedlm(somefilepath, ',', \[header ; x\]) However, when I implement the code, all I get is a file with…

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## [Discourse dark theme kind of bad](https://discourse.julialang.org/t/discourse-dark-theme-kind-of-bad/38766)

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**Author:** [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Replies:** 4\
**Last updated:** [May 5, 2020, 7:47am UTC](https://discourse.julialang.org/t/discourse-dark-theme-kind-of-bad/38766 "2020-05-05T07:47:48Z")

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I’m not sure if this is the right place for this question, but when I use the dark mode of discourse for Julia, the like button and some other things become basically invisible. Is there an easy way to fix this?

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## [Minimize function of matrix subject to matrix equality](https://discourse.julialang.org/t/minimize-function-of-matrix-subject-to-matrix-equality/38701)

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**Author:** [@uncertainly](https://discourse.julialang.org/u/uncertainly)\
**Replies:** 5\
**Last updated:** [May 5, 2020, 3:06am UTC](https://discourse.julialang.org/t/minimize-function-of-matrix-subject-to-matrix-equality/38701 "2020-05-05T03:06:02Z")

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newbie here, both to julia, JuMP, only intermediate at optimization. I would like to solve a problem min(A) subject to C = B\*A where A,B,C are all matrices. Is it possible to express this in JuMP? Any h…

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## [Why a 10,000 message limit promotes better communication for large communities](https://discourse.julialang.org/t/why-a-10-000-message-limit-promotes-better-communication-for-large-communities/38422)

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**Author:** [@logankilpatrick](https://discourse.julialang.org/u/logankilpatrick)\
**Replies:** 17\
**Last updated:** [May 5, 2020, 2:59am UTC](https://discourse.julialang.org/t/why-a-10-000-message-limit-promotes-better-communication-for-large-communities/38422 "2020-05-05T02:59:57Z")

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As the age-old Slack vs Zulip battle continues, I have spent a great deal of time thinking about the implications of using the two platforms. I will attempt to lay out why I think that regardless of the platform, we need…

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## [Presentation to a meetup - call for introductory materials](https://discourse.julialang.org/t/presentation-to-a-meetup-call-for-introductory-materials/37800)

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**Author:** [@Emmanuel-R8](https://discourse.julialang.org/u/Emmanuel-R8)\
**Replies:** 11\
**Last updated:** [May 5, 2020, 2:17am UTC](https://discourse.julialang.org/t/presentation-to-a-meetup-call-for-introductory-materials/37800 "2020-05-05T02:17:51Z")

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I am working on a presentation for the Hong Kong Machine Learning meetup. Audience is very diverse in skills and experience; this is not a technical seminar but we assume the skills to understand the first chapters of th…

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## [Scatterplot with marginal histograms](https://discourse.julialang.org/t/scatterplot-with-marginal-histograms/37619)

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**Author:** [@Humphrey\_Lee](https://discourse.julialang.org/u/Humphrey_Lee)\
**Replies:** 35\
**Last updated:** [May 5, 2020, 12:53am UTC](https://discourse.julialang.org/t/scatterplot-with-marginal-histograms/37619 "2020-05-05T00:53:36Z")

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Any idea how to do scatterplot with marginal histograms in Gadfly or Plots. Preference is Gadfly. Found similar post in forum below, but it was done in R/ggplot2. Technically, each histograms may have (normalized) cumula…

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## [JuMP Optimization Help](https://discourse.julialang.org/t/jump-optimization-help/38740)

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**Author:** [@mthelm85](https://discourse.julialang.org/u/mthelm85)\
**Replies:** 5\
**Last updated:** [May 4, 2020, 11:44pm UTC](https://discourse.julialang.org/t/jump-optimization-help/38740 "2020-05-04T23:44:44Z")

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I’m brand new to JuMP.jl and optimization and I’m running into a bit of a roadblock figuring out how to solve what I thought would be a fairly straightforward problem. Imagine 6 jars of marbles, divided into two groups. …

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## [\[ANN\] Jusdl.jl v0.1.2 - Signal-Flow Graphs, Detecting and Breaking Algebraic Loops](https://discourse.julialang.org/t/ann-jusdl-jl-v0-1-2-signal-flow-graphs-detecting-and-breaking-algebraic-loops/38773)

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**Author:** [@zekeriya.sari](https://discourse.julialang.org/u/zekeriya.sari)\
**Replies:** 0\
**Last updated:** [May 4, 2020, 10:44pm UTC](https://discourse.julialang.org/t/ann-jusdl-jl-v0-1-2-signal-flow-graphs-detecting-and-breaking-algebraic-loops/38773 "2020-05-04T22:44:18Z")

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Hi all, I am pleased to announce the changes in the new patch release v0.1.2 of Jusdl. One big change is that a signal-flow graph(which simply a directed graph consisting of nodes and branches) is associated with the m…

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## [PyPlot graph is too big for plots Pane](https://discourse.julialang.org/t/pyplot-graph-is-too-big-for-plots-pane/38770)

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**Author:** [@JazielSM](https://discourse.julialang.org/u/JazielSM)\
**Replies:** 0\
**Last updated:** [May 4, 2020, 10:39pm UTC](https://discourse.julialang.org/t/pyplot-graph-is-too-big-for-plots-pane/38770 "2020-05-04T22:39:07Z")

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I’m trying different features of different backends with the next simple code: x = 1:10; y = rand(10, 2) pyplot() plot(x, y, title = "Using PyPlot",framestyle=:box) with gr() or plotly(), the graph always fits the siz…

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## [Skew normal distribution?](https://discourse.julialang.org/t/skew-normal-distribution/21549)

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**Author:** [@bsprung](https://discourse.julialang.org/u/bsprung)\
**Replies:** 9\
**Last updated:** [May 4, 2020, 10:32pm UTC](https://discourse.julialang.org/t/skew-normal-distribution/21549 "2020-05-04T22:32:39Z")

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Hi, does anyone know if there is an implementation in any package of the skew normal distribution? There doesn’t appear to be one in Distributions.jl. Thank you!

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## [How to set Cbc Parameters](https://discourse.julialang.org/t/how-to-set-cbc-parameters/38516)

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**Author:** [@lausilvag](https://discourse.julialang.org/u/lausilvag)\
**Replies:** 3\
**Last updated:** [May 4, 2020, 10:28pm UTC](https://discourse.julialang.org/t/how-to-set-cbc-parameters/38516 "2020-05-04T22:28:58Z")

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Hi I am trying to set parameters for Cbc Solver Z\_OP = Model(with\_optimizer(Cbc.Optimizer)) set\_parameter(Z\_OP, "preProcess", off) set\_parameter(Z\_OP, "CliqueCuts", Root) error: UndefVarError: Off not defined …

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## [Dynamic programming](https://discourse.julialang.org/t/dynamic-programming/38512)

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**Author:** [@lausilvag](https://discourse.julialang.org/u/lausilvag)\
**Replies:** 4\
**Last updated:** [May 4, 2020, 10:28pm UTC](https://discourse.julialang.org/t/dynamic-programming/38512 "2020-05-04T22:28:12Z")

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Hi I am new to Julia and I would like to know if there is any MIP optimization solver that performs dynamic search. I have an optimization problem that exceeds 1000 variables allowed by student/research CPLEX license. …

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## [Julia to Python workspace transfer](https://discourse.julialang.org/t/julia-to-python-workspace-transfer/38742)

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**Author:** [@samantp](https://discourse.julialang.org/u/samantp)\
**Replies:** 2\
**Last updated:** [May 4, 2020, 9:17pm UTC](https://discourse.julialang.org/t/julia-to-python-workspace-transfer/38742 "2020-05-04T21:17:41Z")

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I have some scripts in Julia and some in Python (unfortunately this could not have been avoided). It would be useful for me to save some of my Julia workspace variables (specifically, a dictionary consisting of keys and …

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## [New machine learning package, Julia implementation of XGBoost ](https://discourse.julialang.org/t/new-machine-learning-package-julia-implementation-of-xgboost/8912)

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**Author:** [@statfactory](https://discourse.julialang.org/u/statfactory)\
**Replies:** 32\
**Last updated:** [March 10, 2020, 6:47am UTC](https://discourse.julialang.org/t/new-machine-learning-package-julia-implementation-of-xgboost/8912 "2020-03-10T06:47:49Z")

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Hi, I am working on a new Julia machine learning package. What I have now is a pure Julia implementation of XGBoost in \< 500 lines of code: https://github.com/Statfactory/JuML.jl It seems to be as fast as original XGB…

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## [Create a colorbar given the range of levelset and colors](https://discourse.julialang.org/t/create-a-colorbar-given-the-range-of-levelset-and-colors/38763)

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**Author:** [@mleprovost](https://discourse.julialang.org/u/mleprovost)\
**Replies:** 0\
**Last updated:** [May 4, 2020, 8:40pm UTC](https://discourse.julialang.org/t/create-a-colorbar-given-the-range-of-levelset-and-colors/38763 "2020-05-04T20:40:07Z")

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Hello, I would like to plot only the colorbar, given the range of level sets clims and the range of color to use. I have something like this in mind: using Plots colorbar(clims = (-2, 2), color = cgrad((colormap("RdBu…

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## [Is it possible to display a "turtle" .svg in the juno plot pane](https://discourse.julialang.org/t/is-it-possible-to-display-a-turtle-svg-in-the-juno-plot-pane/38588)

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**Author:** [@spence](https://discourse.julialang.org/u/spence)\
**Replies:** 5\
**Last updated:** [May 4, 2020, 8:26pm UTC](https://discourse.julialang.org/t/is-it-possible-to-display-a-turtle-svg-in-the-juno-plot-pane/38588 "2020-05-04T20:26:03Z")

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I’m going through the “Think Julia” book, I’m in chapter 4 creating turtle drawings. Is there a way to view my drawing in the Juno plot pane so I don’t have to go back and forth between Juno and my file manager to verify…

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## [Tables.jl: columntable to rowtable](https://discourse.julialang.org/t/tables-jl-columntable-to-rowtable/36112)

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**Author:** [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Replies:** 6\
**Last updated:** [May 4, 2020, 7:58pm UTC](https://discourse.julialang.org/t/tables-jl-columntable-to-rowtable/36112 "2020-05-04T19:58:01Z")

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I’m trying to implement an interface to a column-based table storage backend, but struggle to make it work efficiently. The minimal implementation looks like this: import Tables struct MyTable \<: Tables.AbstractColumns…

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## [Using push! on a plot with time objects](https://discourse.julialang.org/t/using-push-on-a-plot-with-time-objects/38750)

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**Author:** [@achugb](https://discourse.julialang.org/u/achugb)\
**Replies:** 4\
**Last updated:** [May 4, 2020, 6:17pm UTC](https://discourse.julialang.org/t/using-push-on-a-plot-with-time-objects/38750 "2020-05-04T18:17:10Z")

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Is there a way to push additional datapoints to a plot when using time objects? The code below throws an error. Am I doing something wrong? using Plots using Dates x = \[now(), now() + Second(1)\] p = plot(Time.(x), 1:2)…

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