# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=552

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**Page:** 553

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## [Julia DataFrames -\> plot 48 times slower than Python Pandas](https://discourse.julialang.org/t/julia-dataframes-plot-48-times-slower-than-python-pandas/6138)

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**Author:** [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Replies:** 16\
**Last updated:** [October 3, 2017, 10:28am UTC](https://discourse.julialang.org/t/julia-dataframes-plot-48-times-slower-than-python-pandas/6138 "2017-10-03T10:28:09Z")

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I use the same methods and data in both Python and Julia (except that the Python plot has much more work as far as the attributes of the plot is concerned). I am fairly new to both Python Pandas and Julia DataFrames and…

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## [ANN: uCSV.jl](https://discourse.julialang.org/t/ann-ucsv-jl/6162)

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**Author:** [@cjprybol](https://discourse.julialang.org/u/cjprybol)\
**Replies:** 4\
**Last updated:** [October 3, 2017, 8:04am UTC](https://discourse.julialang.org/t/ann-ucsv-jl/6162 "2017-10-03T08:04:40Z")

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uCSV.jl is a µ-sized package for working with delimited text. The default behavior is similar to readcsv from base, but it is extensible enough to cover just about everything you’d expect from more established parsers in…

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## [How to open a graphics file on Windows using run()](https://discourse.julialang.org/t/how-to-open-a-graphics-file-on-windows-using-run/2955)

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**Author:** [@cormullion](https://discourse.julialang.org/u/cormullion)\
**Replies:** 6\
**Last updated:** [October 2, 2017, 4:50pm UTC](https://discourse.julialang.org/t/how-to-open-a-graphics-file-on-windows-using-run/2955 "2017-10-02T16:50:02Z")

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On macOS I can do this: run(\`open $(filename)\`) where filename might be image.png or /tmp/test.pdf or /Users/me/test.svg, and the file will open in Preview or Safari or whatever app you’ve decided to make the default f…

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## [Porting MLKernels.jl to Julia v0.6](https://discourse.julialang.org/t/porting-mlkernels-jl-to-julia-v0-6/6191)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 2\
**Last updated:** [October 2, 2017, 3:12pm UTC](https://discourse.julialang.org/t/porting-mlkernels-jl-to-julia-v0-6/6191 "2017-10-02T15:12:28Z")

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I am finishing a PR for fixing MLKernels.jl in Julia v0.6. I got stuck with the following issue. Suppose I have code of the form: abstract type B{T} end abstract type C{T} \<: B{T} end struct D1{T} \<: B{T} end struct D2…

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## [JuMP Efficient Quadratic Objective Formulation](https://discourse.julialang.org/t/jump-efficient-quadratic-objective-formulation/6177)

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**Author:** [@Kenney](https://discourse.julialang.org/u/Kenney)\
**Replies:** 4\
**Last updated:** [October 1, 2017, 7:44pm UTC](https://discourse.julialang.org/t/jump-efficient-quadratic-objective-formulation/6177 "2017-10-01T19:44:13Z")

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Hi everyone, I (eventually) want to run an MIQP where the objective is a simple sum of squares say sum((Y-XB)^2). Without even getting to the constraints or the integer part of the problem, I’m running into issues simpl…

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## [Dynamical Systems API and ChaosTools.jl](https://discourse.julialang.org/t/dynamical-systems-api-and-chaostools-jl/4041)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 22\
**Last updated:** [October 1, 2017, 11:29am UTC](https://discourse.julialang.org/t/dynamical-systems-api-and-chaostools-jl/4041 "2017-10-01T11:29:35Z")

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I have recently started on a journey to create a package ChaosTools.jl that has common useful tools used in the study of nonlinear dynamics and chaos, like e.g. lyapunov exponents, attractor dimension estimation and othe…

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## [Costates and Hamiltonian in JuMP and MathProgbase](https://discourse.julialang.org/t/costates-and-hamiltonian-in-jump-and-mathprogbase/6160)

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**Author:** [@huckl3b3rry87](https://discourse.julialang.org/u/huckl3b3rry87)\
**Replies:** 4\
**Last updated:** [October 1, 2017, 2:53am UTC](https://discourse.julialang.org/t/costates-and-hamiltonian-in-jump-and-mathprogbase/6160 "2017-10-01T02:53:42Z")

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Part # 1 I was interested in getting the costates. The costates are also known as the lagrange multipliers or dual variables. I looked through the MathProgBase docs and found this function called getconstduals does that…

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## [Parallelization of simple loop: reductions, thread-private variables?](https://discourse.julialang.org/t/parallelization-of-simple-loop-reductions-thread-private-variables/5051)

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**Author:** [@antoine-levitt](https://discourse.julialang.org/u/antoine-levitt)\
**Replies:** 9\
**Last updated:** [September 30, 2017, 9:52pm UTC](https://discourse.julialang.org/t/parallelization-of-simple-loop-reductions-thread-private-variables/5051 "2017-09-30T21:52:37Z")

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Hi, I’m looking for a way to parallelize a simple loop I have. I don’t want to get into the complexity of distributed computing, but I’d like something similar to OpenMP. My code structure is basically similar to this: …

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## [\[JuMP\] Pure integer solutions (Combinatorial optimization?)](https://discourse.julialang.org/t/jump-pure-integer-solutions-combinatorial-optimization/6151)

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**Author:** [@artagnon](https://discourse.julialang.org/u/artagnon)\
**Replies:** 6\
**Last updated:** [September 30, 2017, 2:46pm UTC](https://discourse.julialang.org/t/jump-pure-integer-solutions-combinatorial-optimization/6151 "2017-09-30T14:46:50Z")

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Hi, I’m investigating the use of JuMP for a million-client scheduling service. Since there are certain hard constraints like “belongs to set” and binary variables like “either scheduled or not scheduled”, and simple con…

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## [ANN: Julia bindings for ensemble empirical mode decomp](https://discourse.julialang.org/t/ann-julia-bindings-for-ensemble-empirical-mode-decomp/886)

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**Author:** [@merl-dev](https://discourse.julialang.org/u/merl-dev)\
**Replies:** 2\
**Last updated:** [September 29, 2017, 7:09pm UTC](https://discourse.julialang.org/t/ann-julia-bindings-for-ensemble-empirical-mode-decomp/886 "2017-09-29T19:09:59Z")

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I’ll be doing some work over the next few months that makes use of an interesting approach to signal processing developed in the late 90s called the empirical mode decomposition. Used primarily in the analysis of nonlin…

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## [The two arrows in the juno plotting panel?](https://discourse.julialang.org/t/the-two-arrows-in-the-juno-plotting-panel/2967)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 8\
**Last updated:** [September 29, 2017, 12:46pm UTC](https://discourse.julialang.org/t/the-two-arrows-in-the-juno-plotting-panel/2967 "2017-09-29T12:46:55Z")

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The two arrows behind the title in the juno plotting panel should supposedly allow to switch between several plots in memory, but they are not clickable on my juno installation. Not yet implemented, something not workin…

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## [Issues with multiple @let statements in Query.jl](https://discourse.julialang.org/t/issues-with-multiple-let-statements-in-query-jl/4494)

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**Author:** [@Matt\_Amos](https://discourse.julialang.org/u/Matt_Amos)\
**Replies:** 5\
**Last updated:** [September 29, 2017, 5:38am UTC](https://discourse.julialang.org/t/issues-with-multiple-let-statements-in-query-jl/4494 "2017-09-29T05:38:19Z")

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Whenever I try to use more than two @let statements in my query I get an error (Julia version 0.6.0, Query.jl 0.6.0). DataFrame sink: type TypeofBottom has no field parameters Array sink: TypeError: getfield: expecte…

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## [Help with binary uncertain paremeters in JuMPeR](https://discourse.julialang.org/t/help-with-binary-uncertain-paremeters-in-jumper/6149)

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**Author:** [@gavelasq](https://discourse.julialang.org/u/gavelasq)\
**Replies:** 0\
**Last updated:** [September 29, 2017, 12:09am UTC](https://discourse.julialang.org/t/help-with-binary-uncertain-paremeters-in-jumper/6149 "2017-09-29T00:09:27Z")

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Hi, can anyone have an model example where binary uncertain paremeters in JuMPeR such as: highways = \[:I90, :I93, :I95\] @uncertain(rm, blocked\[highways\], Bin) are used? thanks.

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## [Why does plot use floats on X-axis when an Int16\[\] was supplied?](https://discourse.julialang.org/t/why-does-plot-use-floats-on-x-axis-when-an-int16-was-supplied/6132)

<div class="topic-metadata">

**Author:** [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Replies:** 2\
**Last updated:** [September 28, 2017, 8:38am UTC](https://discourse.julialang.org/t/why-does-plot-use-floats-on-x-axis-when-an-int16-was-supplied/6132 "2017-09-28T08:38:22Z")

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I am trying to find my feet in Julia and Plotting. When I plot df (see below) the xticks shows values like 2005.0 2007.5 2010.0 2012.5 2015.0 while the range is of the type Int16. I could, after several hours of read…

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## [Problem Installing RDatasets and DataFrames](https://discourse.julialang.org/t/problem-installing-rdatasets-and-dataframes/6121)

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**Author:** [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Replies:** 5\
**Last updated:** [September 28, 2017, 7:48am UTC](https://discourse.julialang.org/t/problem-installing-rdatasets-and-dataframes/6121 "2017-09-28T07:48:30Z")

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Can someone help me make sure my julia installation is correct? There are a few things that seem sketchy when I try to install and update the DataFrames package and the RDatasets Package First, when I issue the command …

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## [Reading data with dataframe (instead of readdlm), now equations give error](https://discourse.julialang.org/t/reading-data-with-dataframe-instead-of-readdlm-now-equations-give-error/5858)

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**Author:** [@Halil1](https://discourse.julialang.org/u/Halil1)\
**Replies:** 2\
**Last updated:** [September 28, 2017, 7:39am UTC](https://discourse.julialang.org/t/reading-data-with-dataframe-instead-of-readdlm-now-equations-give-error/5858 "2017-09-28T07:39:38Z")

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Hey all, Just because I have changed the way I read the input data, now model equations give me errors. How can I resolve this? More context here: I have successfully run optimization model when I was reading the csv …

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## [DataFrames: why is \`df\[2,\]\` the same as \`df\[2\]\`?](https://discourse.julialang.org/t/dataframes-why-is-df-2-the-same-as-df-2/6053)

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**Author:** [@nickeubank](https://discourse.julialang.org/u/nickeubank)\
**Replies:** 17\
**Last updated:** [September 27, 2017, 9:33pm UTC](https://discourse.julialang.org/t/dataframes-why-is-df-2-the-same-as-df-2/6053 "2017-09-27T21:33:53Z")

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Curious about the rationale for this. Seems like df\[2,\] should either be the second row (same as df\[2,:\]) or an error. Thanks

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## [Help needed with DataFrames and Query](https://discourse.julialang.org/t/help-needed-with-dataframes-and-query/6077)

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**Author:** [@johann.spies](https://discourse.julialang.org/u/johann.spies)\
**Replies:** 8\
**Last updated:** [September 27, 2017, 1:01pm UTC](https://discourse.julialang.org/t/help-needed-with-dataframes-and-query/6077 "2017-09-27T13:01:26Z")

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I am learning how to use DataFrames and find am struggling to use it for what I need it for. My present problem is illustrated by this attempt to use Quey.jl. I cannot understand why there result of q1 has no values. A…

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## [TensorFlow: argument evaluation](https://discourse.julialang.org/t/tensorflow-argument-evaluation/6111)

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**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 0\
**Last updated:** [September 27, 2017, 12:35pm UTC](https://discourse.julialang.org/t/tensorflow-argument-evaluation/6111 "2017-09-27T12:35:00Z")

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In following Lyndon White’s example of TensorFlow at JuliaML and TensorFlow Tuitorial I was able to get it to run successfully after two changes: reduce\_sum uses the now deprecated (and refused on my 1.4 dev TF) reduct…

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## [Adding Excel File to Jupyter Notebook](https://discourse.julialang.org/t/adding-excel-file-to-jupyter-notebook/6098)

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**Author:** [@ivanlarsen13](https://discourse.julialang.org/u/ivanlarsen13)\
**Replies:** 1\
**Last updated:** [September 27, 2017, 5:28am UTC](https://discourse.julialang.org/t/adding-excel-file-to-jupyter-notebook/6098 "2017-09-27T05:28:33Z")

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Hello, I installed the ExcelReaders package from github, and on Jupyter Notebook I write: using ExcelReaders data = readxlsheet(“http://localhost:8889/view/Desktop/UT%20Austin%20Econ/2nd%20Year/IO/Filename.xlsx”, “She…

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## [Knet questions](https://discourse.julialang.org/t/knet-questions/5716)

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**Author:** [@Phil\_Tomson](https://discourse.julialang.org/u/Phil_Tomson)\
**Replies:** 2\
**Last updated:** [September 26, 2017, 7:42pm UTC](https://discourse.julialang.org/t/knet-questions/5716 "2017-09-26T19:42:37Z")

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Unfortunately, the knet.jl intro video from the 2017 Julia Conf seems to be missing audio for at least half of the talk… One thing I noticed was that there was a slide that defined a function using an @knet macro: @kne…

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## [In place lufact for sparse matrices and prellocation for lufact output](https://discourse.julialang.org/t/in-place-lufact-for-sparse-matrices-and-prellocation-for-lufact-output/6090)

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**Author:** [@tryingtosolve](https://discourse.julialang.org/u/tryingtosolve)\
**Replies:** 1\
**Last updated:** [September 26, 2017, 5:41pm UTC](https://discourse.julialang.org/t/in-place-lufact-for-sparse-matrices-and-prellocation-for-lufact-output/6090 "2017-09-26T17:41:25Z")

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Currently there is a lufact! for dense matrices. Is there an equivalent of lufact! for sparse matrices? Also, related to that, how do I preallocate for the output of lufact(A), assuming that A is a sparse matrix? This i…

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## [How to change value of Nullable{WeakRefString{UInt8}} using CSV package?](https://discourse.julialang.org/t/how-to-change-value-of-nullable-weakrefstring-uint8-using-csv-package/6080)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 4\
**Last updated:** [September 26, 2017, 1:14pm UTC](https://discourse.julialang.org/t/how-to-change-value-of-nullable-weakrefstring-uint8-using-csv-package/6080 "2017-09-26T13:14:00Z")

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Hi ! I try to work with the CSV package and I have some problem to change the value of a DataFrame entry because of the Nullable{WeakRefString{UInt8}} type. I do not know in advance the types of the columns so the defa…

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## [Does an epidemiology package exist?](https://discourse.julialang.org/t/does-an-epidemiology-package-exist/6063)

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**Author:** [@malavv](https://discourse.julialang.org/u/malavv)\
**Replies:** 3\
**Last updated:** [September 26, 2017, 1:11pm UTC](https://discourse.julialang.org/t/does-an-epidemiology-package-exist/6063 "2017-09-26T13:11:16Z")

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Hi! I am a PhD student in Epidemiology and since I saw Julia, I always wanted to try it out as a “new R”. As an epidemiologist, Epidemiology packages in R that provides support for contingency tables, risk ratios, and o…

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## [How to save random number generator state?](https://discourse.julialang.org/t/how-to-save-random-number-generator-state/6034)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 4\
**Last updated:** [September 22, 2017, 6:18pm UTC](https://discourse.julialang.org/t/how-to-save-random-number-generator-state/6034 "2017-09-22T18:18:10Z")

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Suppose I have a loop where I generate samples with a stochastic function: srand(2017) for i=1:1000 sample = stochastic\_function(deterministic\_parameters...) end I need to save the state in order to be able to do so…

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## [How to identify local maxima (peaks) in a time signal?](https://discourse.julialang.org/t/how-to-identify-local-maxima-peaks-in-a-time-signal/6000)

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**Author:** [@ceysa75](https://discourse.julialang.org/u/ceysa75)\
**Replies:** 5\
**Last updated:** [September 22, 2017, 2:20pm UTC](https://discourse.julialang.org/t/how-to-identify-local-maxima-peaks-in-a-time-signal/6000 "2017-09-22T14:20:10Z")

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Hi folks, making my first steps in Julia with the basic aim to finally get rid of Matlab. I am searching for a package which helps me identiying local extremes, i.e. peak values, from a monitored time signal (decaying v…

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## [Error saving as SVG SystemError: opening file tikzpicture.log: No such file or directory](https://discourse.julialang.org/t/error-saving-as-svg-systemerror-opening-file-tikzpicture-log-no-such-file-or-directory/5960)

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**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 12\
**Last updated:** [September 22, 2017, 4:43am UTC](https://discourse.julialang.org/t/error-saving-as-svg-systemerror-opening-file-tikzpicture-log-no-such-file-or-directory/5960 "2017-09-22T04:43:11Z")

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I get the above error when I try to plot using Plots.jl with pgfplots() as a backend. Any idea what is missing? double posting

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## [UnitfulAstro.jl](https://discourse.julialang.org/t/unitfulastro-jl/6004)

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**Author:** [@Michael\_Eastwood](https://discourse.julialang.org/u/Michael_Eastwood)\
**Replies:** 9\
**Last updated:** [September 21, 2017, 4:05pm UTC](https://discourse.julialang.org/t/unitfulastro-jl/6004 "2017-09-21T16:05:30Z")

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Hello fellow astro Julians. I’ve finally gotten around to polishing up a package that I’ve wanted to have for a very long time. That is, a units package that includes a bunch of the crazy astronomy units that we’ve come…

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## [DataFrame : eltypes with variable length](https://discourse.julialang.org/t/dataframe-eltypes-with-variable-length/6016)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 2\
**Last updated:** [September 21, 2017, 10:02am UTC](https://discourse.julialang.org/t/dataframe-eltypes-with-variable-length/6016 "2017-09-21T10:02:00Z")

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Hi, The function readtable(filename, \[keyword options\]) as an optional keyword eltypes::Vector – Specify the types of all columns. Defaults to \[\]. When the exact size of the table, it is possible to specify the type…

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## [Implementing parallel fluids code in Julia (parallel FFTW, MPI.jl, ...)](https://discourse.julialang.org/t/implementing-parallel-fluids-code-in-julia-parallel-fftw-mpi-jl/2689)

<div class="topic-metadata">

**Author:** [@John\_Gibson](https://discourse.julialang.org/u/John_Gibson)\
**Replies:** 34\
**Last updated:** [September 21, 2017, 6:46am UTC](https://discourse.julialang.org/t/implementing-parallel-fluids-code-in-julia-parallel-fftw-mpi-jl/2689 "2017-09-21T06:46:08Z")

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I’m considering implementing a parallel fluid simulation code in Julia, either reimplementing my Fourier-Chebyshev http://www.channelflow.org code, or doing a simpler isotropic turbulence in a triply-periodic cube as a s…

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