# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=545

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**Page:** 546

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## [Confused \`spdiagm\` with matlab function](https://discourse.julialang.org/t/confused-spdiagm-with-matlab-function/8525)

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**Author:** [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Replies:** 4\
**Last updated:** [January 22, 2018, 5:16pm UTC](https://discourse.julialang.org/t/confused-spdiagm-with-matlab-function/8525 "2018-01-22T17:16:33Z")

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I’m having issues running cholfact on a sparse tridiagonal matrix (Julia v0.6) which works in matlab. When I try to factor L: L = spdiagm((-1.\*v,10.\*v,-1.\*v),(-1,0,1)) println(typeof(L)) cholfact(L) I get: SparseMatri…

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## [JuMP : Adding variables/constraints to a model dynamically](https://discourse.julialang.org/t/jump-adding-variables-constraints-to-a-model-dynamically/3974)

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**Author:** [@Julie](https://discourse.julialang.org/u/Julie)\
**Replies:** 8\
**Last updated:** [October 27, 2017, 12:51pm UTC](https://discourse.julialang.org/t/jump-adding-variables-constraints-to-a-model-dynamically/3974 "2017-10-27T12:51:32Z")

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Is it possible to add dynamically constraints and/or variables to a model? I know there is a syntax to add variable (for column generation) but in the documentation I found that “Some solvers do not expose the ability t…

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## [Optimization routines for Bigfloat/doubledouble/higher precision objective and gradient functions?](https://discourse.julialang.org/t/optimization-routines-for-bigfloat-doubledouble-higher-precision-objective-and-gradient-functions/8448)

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**Author:** [@egcjm](https://discourse.julialang.org/u/egcjm)\
**Replies:** 3\
**Last updated:** [January 19, 2018, 4:46pm UTC](https://discourse.julialang.org/t/optimization-routines-for-bigfloat-doubledouble-higher-precision-objective-and-gradient-functions/8448 "2018-01-19T16:46:18Z")

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Are there Julia optimizers that operate on bigfloat/doubledouble/higher precision objective and gradient functions? I am specifically interested in a L-BGFS functionality for higher that double precision.

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## [Solvers, nonlinear constraints and user defined functions](https://discourse.julialang.org/t/solvers-nonlinear-constraints-and-user-defined-functions/4690)

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**Author:** [@kguo](https://discourse.julialang.org/u/kguo)\
**Replies:** 10\
**Last updated:** [January 18, 2018, 1:17pm UTC](https://discourse.julialang.org/t/solvers-nonlinear-constraints-and-user-defined-functions/4690 "2018-01-18T13:17:28Z")

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I apologize if someone had raised questions like this. And I understand the topic sounded similar to some previous topics. I did do a search. But didn’t found specific answers to all the questions I have. I understan…

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## [Text in figure using PyPlot](https://discourse.julialang.org/t/text-in-figure-using-pyplot/1337)

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**Author:** [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Replies:** 7\
**Last updated:** [January 17, 2018, 5:33am UTC](https://discourse.julialang.org/t/text-in-figure-using-pyplot/1337 "2018-01-17T05:33:27Z")

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I’m trying to add some text in a figure made by PyPlot. It seems that the matplotlib command text doesn’t work in PyPlot. So annotate is the only option? Another question is how to have the in-figure texts tilted/rotate…

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## [Append!() function extremely slow in DataFrames + CSV](https://discourse.julialang.org/t/append-function-extremely-slow-in-dataframes-csv/8396)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 14\
**Last updated:** [January 16, 2018, 2:21pm UTC](https://discourse.julialang.org/t/append-function-extremely-slow-in-dataframes-csv/8396 "2018-01-16T14:21:16Z")

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Hi, When I switched to CSV instead of readtable() to read tabular data, I was surprised to see an extreme slowdown. I attached a small benchmark which seems to indicate that the slowdown is in the append!() function. T…

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## [Plots units of measure](https://discourse.julialang.org/t/plots-units-of-measure/8323)

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**Author:** [@bbrunaud](https://discourse.julialang.org/u/bbrunaud)\
**Replies:** 2\
**Last updated:** [January 12, 2018, 9:04pm UTC](https://discourse.julialang.org/t/plots-units-of-measure/8323 "2018-01-12T21:04:49Z")

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Hello I had a plot code using margins that was working correctly. I started getting the following error plot(pl1,pl2,layout=grid(2,1,heights=\[0.7,0.2\]),size=(800,400),left\_margin=10) MethodError: no method matching +(…

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## [When the function is parallaxed, the speed drops](https://discourse.julialang.org/t/when-the-function-is-parallaxed-the-speed-drops/8282)

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**Author:** [@1112](https://discourse.julialang.org/u/1112)\
**Replies:** 2\
**Last updated:** [January 11, 2018, 10:51am UTC](https://discourse.julialang.org/t/when-the-function-is-parallaxed-the-speed-drops/8282 "2018-01-11T10:51:40Z")

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How can I speed this code up? function scalar\_mult(k::BigInt) .... end function twofor(n) @sync @parallel for i in 1000:n for j in 10:115 scalar\_mult(BigInt(j \* ^(10,3)+i)) end …

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## [Error solve JuMP models in parallel](https://discourse.julialang.org/t/error-solve-jump-models-in-parallel/8250)

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**Author:** [@CanLi1](https://discourse.julialang.org/u/CanLi1)\
**Replies:** 6\
**Last updated:** [January 10, 2018, 4:53pm UTC](https://discourse.julialang.org/t/error-solve-jump-models-in-parallel/8250 "2018-01-10T16:53:32Z")

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Hi folks, I’m new to Julia. I’m solving some JuMP models in parallel and I encountered the following error. The smallest example that I can come up with is as follows: smallmodel.jl using JuMP using Ipopt function g…

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## [Is there any way to describe worker number in each machine?](https://discourse.julialang.org/t/is-there-any-way-to-describe-worker-number-in-each-machine/8249)

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**Author:** [@jwu](https://discourse.julialang.org/u/jwu)\
**Replies:** 2\
**Last updated:** [January 9, 2018, 8:23pm UTC](https://discourse.julialang.org/t/is-there-any-way-to-describe-worker-number-in-each-machine/8249 "2018-01-09T20:23:20Z")

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I know that one way is repeating the hostname N times to have N workers. Is there a way to explicitly say hostname N ?

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## [Genetic Programming for predicting equations of motion](https://discourse.julialang.org/t/genetic-programming-for-predicting-equations-of-motion/8211)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 14\
**Last updated:** [January 9, 2018, 12:24pm UTC](https://discourse.julialang.org/t/genetic-programming-for-predicting-equations-of-motion/8211 "2018-01-09T12:24:28Z")

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Hello people! We want to start a new bachelor project soon, with the goal of using Genetic Programming to somehow predict equations of motion from timeseries. There has been quite some work on this field, notably the pu…

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## [Tset error while trying loading machinefile using multiple machines](https://discourse.julialang.org/t/tset-error-while-trying-loading-machinefile-using-multiple-machines/8238)

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**Author:** [@jwu](https://discourse.julialang.org/u/jwu)\
**Replies:** 2\
**Last updated:** [January 8, 2018, 10:41pm UTC](https://discourse.julialang.org/t/tset-error-while-trying-loading-machinefile-using-multiple-machines/8238 "2018-01-08T22:41:26Z")

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I can ssh login without password, but still get some errors. My machinefile format is “host”, one host for each line. I started julia using julia --machinefile machinefile but get some tset errors. Any ideas? tset:…

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## [Solving Stochastic Differential Equations with Same Random Numbers](https://discourse.julialang.org/t/solving-stochastic-differential-equations-with-same-random-numbers/8189)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 3\
**Last updated:** [January 7, 2018, 11:06am UTC](https://discourse.julialang.org/t/solving-stochastic-differential-equations-with-same-random-numbers/8189 "2018-01-07T11:06:56Z")

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One Line Question: How do I use Julia to solve a system of Stochastic Differential Equations were there are correlated terms of noise (or “the same” noise appears in several places) Biological Background: Lets say I hav…

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## [Simple Knet.jl Question: save/load model?](https://discourse.julialang.org/t/simple-knet-jl-question-save-load-model/8202)

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**Author:** [@Joshua\_Bowles](https://discourse.julialang.org/u/Joshua_Bowles)\
**Replies:** 2\
**Last updated:** [January 6, 2018, 7:35pm UTC](https://discourse.julialang.org/t/simple-knet-jl-question-save-load-model/8202 "2018-01-06T19:35:41Z")

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I’m new to julia (as of last week; toyed a bit long time ago with v0.2). I’ve looked over previous Knet posts, searched docs, and Knet (stable) source but can’t find an example of saving/loading a model. I see what look…

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## [\[ANN\]: Gaston v0.7.0 - Plotting using gnuplot](https://discourse.julialang.org/t/ann-gaston-v0-7-0-plotting-using-gnuplot/8063)

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**Author:** [@mbaz](https://discourse.julialang.org/u/mbaz)\
**Replies:** 2\
**Last updated:** [January 6, 2018, 2:09pm UTC](https://discourse.julialang.org/t/ann-gaston-v0-7-0-plotting-using-gnuplot/8063 "2018-01-06T14:09:03Z")

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Sorry for the duplicate information, but I thought some people may be interested in this and do not follow Community. There’s a new version of the Gaston plotting package; the full announcement is here.

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## [Initialize a nonlinear model](https://discourse.julialang.org/t/initialize-a-nonlinear-model/8190)

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**Author:** [@CanLi1](https://discourse.julialang.org/u/CanLi1)\
**Replies:** 2\
**Last updated:** [January 6, 2018, 12:31am UTC](https://discourse.julialang.org/t/initialize-a-nonlinear-model/8190 "2018-01-06T00:31:47Z")

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Hi folks, In GAMS, we can initialize a nonlinear model by setting variable.l = initial\_value. I’m wondering how this can be done in JuMP, i.e., how can we initialize the primal variables of a JuMP model before we use th…

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## [How to launch the julia on cluster under Torque scheduler](https://discourse.julialang.org/t/how-to-launch-the-julia-on-cluster-under-torque-scheduler/8155)

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**Author:** [@Anna\_W](https://discourse.julialang.org/u/Anna_W)\
**Replies:** 2\
**Last updated:** [January 5, 2018, 9:36pm UTC](https://discourse.julialang.org/t/how-to-launch-the-julia-on-cluster-under-torque-scheduler/8155 "2018-01-05T21:36:00Z")

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Hello, I would be grateful for any help. I was successful in using the ClusterManager.jl package udder slurm scheduler. But I had to switch to another cluster with the torque scheduler and the addprocs() and addprocs\_…

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## [Error when passing long array of data to Turing.jl](https://discourse.julialang.org/t/error-when-passing-long-array-of-data-to-turing-jl/8098)

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**Author:** [@EricChameroy](https://discourse.julialang.org/u/EricChameroy)\
**Replies:** 0\
**Last updated:** [January 1, 2018, 10:05pm UTC](https://discourse.julialang.org/t/error-when-passing-long-array-of-data-to-turing-jl/8098 "2018-01-01T22:05:17Z")

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Hi everyone, I’m trying to pass an array of data through a model I’ve created using Turing.jl. The model looks like this: @model howell1(height) = begin mu ~ Normal(178, 20) sigma ~ Uniform(0, 50) \[height\[i\] ~ Norma…

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## [Write CSV with nulls from dataframe](https://discourse.julialang.org/t/write-csv-with-nulls-from-dataframe/8167)

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**Author:** [@jonjilla](https://discourse.julialang.org/u/jonjilla)\
**Replies:** 3\
**Last updated:** [January 5, 2018, 7:49am UTC](https://discourse.julialang.org/t/write-csv-with-nulls-from-dataframe/8167 "2018-01-05T07:49:43Z")

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I’m trying to write a CSV file using the CSV.jl package but am getting this error julia\> CSV.write(“/tmp/out.csv”,testmap) ERROR: TypeError: streamto!: in typeassert, expected String, got DataArrays.NAtype I thought t…

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## [ANN: InplaceRealFFT.jl : inplace real-to-complex and complex-to-real FFT](https://discourse.julialang.org/t/ann-inplacerealfft-jl-inplace-real-to-complex-and-complex-to-real-fft/8116)

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**Author:** [@favba](https://discourse.julialang.org/u/favba)\
**Replies:** 25\
**Last updated:** [January 5, 2018, 6:32am UTC](https://discourse.julialang.org/t/ann-inplacerealfft-jl-inplace-real-to-complex-and-complex-to-real-fft/8116 "2018-01-05T06:32:50Z")

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Hello everyone! I’ve created the InplaceRealFFT.jl module to expose FFTW’s inplace real-to-complex (rfft!) and complex-to-real (irfft!) transformations. Currently, Julia only provides inplace version of the transform f…

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## [JuMP, LinearProg, How to get problem data in form min (c^t)x s.t. Ax = b, x \>= 0](https://discourse.julialang.org/t/jump-linearprog-how-to-get-problem-data-in-form-min-c-t-x-s-t-ax-b-x-0/8100)

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**Author:** [@pedroborgesmelo](https://discourse.julialang.org/u/pedroborgesmelo)\
**Replies:** 4\
**Last updated:** [January 3, 2018, 10:12pm UTC](https://discourse.julialang.org/t/jump-linearprog-how-to-get-problem-data-in-form-min-c-t-x-s-t-ax-b-x-0/8100 "2018-01-03T22:12:22Z")

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Hey Guys! When I model a LP with JuMP, is it possible get the problem data in the form min (c^t)x s.t. Ax = b, x \>= 0 easily ? I mean, with a function already existing? If not, what is an easy way? Thanks in advance,

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## [Addprocs() error, add remote machine](https://discourse.julialang.org/t/addprocs-error-add-remote-machine/8119)

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**Author:** [@zhangliye](https://discourse.julialang.org/u/zhangliye)\
**Replies:** 1\
**Last updated:** [January 3, 2018, 6:14am UTC](https://discourse.julialang.org/t/addprocs-error-add-remote-machine/8119 "2018-01-03T06:14:14Z")

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I have several machines in the LAN, and run the addprocs() on one machine to add cores from another remote machine. I do not know how to set the user password in addprocs(). The error is as follows. Can anyone give me s…

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## [@cuDynamicSharedMem : allocating beforehand?](https://discourse.julialang.org/t/cudynamicsharedmem-allocating-beforehand/8101)

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**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 2\
**Last updated:** [January 2, 2018, 8:41am UTC](https://discourse.julialang.org/t/cudynamicsharedmem-allocating-beforehand/8101 "2018-01-02T08:41:11Z")

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I am getting: ERROR: LoadError: CUDA error: an illegal memory access was encountered (code #700, ERROR\_ILLEGAL\_ADDRESS) on the following using CUDAdrv, CUDAnative function kernel(x) i = threadIdx().x shared = @…

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## [Generating Random Number from inside Kernel](https://discourse.julialang.org/t/generating-random-number-from-inside-kernel/8071)

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**Author:** [@drjoke](https://discourse.julialang.org/u/drjoke)\
**Replies:** 12\
**Last updated:** [January 2, 2018, 5:13am UTC](https://discourse.julialang.org/t/generating-random-number-from-inside-kernel/8071 "2018-01-02T05:13:57Z")

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Is it possible to generate a random number from within a kernel? My reading of CURAND.jl looks like curand() must be called from host. I am implementing Genetic Algorithm. It is becoming impractical to have to pre-gene…

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## [Discussion: OpenGL](https://discourse.julialang.org/t/discussion-opengl/8044)

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**Author:** [@louisponet](https://discourse.julialang.org/u/louisponet)\
**Replies:** 11\
**Last updated:** [December 31, 2017, 7:54pm UTC](https://discourse.julialang.org/t/discussion-opengl/8044 "2017-12-31T19:54:30Z")

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Hi everyone, I would like to open up a discussion with the topic OpenGL, following some considerations made in GLAbstraction.jl issue #87. The situation with all but the core of the julia OpenGL stack is rather non-ide…

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## [ANN: SASLib.jl](https://discourse.julialang.org/t/ann-saslib-jl/8030)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 14\
**Last updated:** [December 30, 2017, 12:45am UTC](https://discourse.julialang.org/t/ann-saslib-jl/8030 "2017-12-30T00:45:50Z")

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Hello everyone! I am happy to announce a new package SASLib.jl. Please see the github project page for more information. -Tom https://github.com/tk3369/SASLib.jl

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## [Replace missing values with .= in DataFrame](https://discourse.julialang.org/t/replace-missing-values-with-in-dataframe/8039)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 2\
**Last updated:** [December 28, 2017, 3:37pm UTC](https://discourse.julialang.org/t/replace-missing-values-with-in-dataframe/8039 "2017-12-28T15:37:35Z")

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The following is an MWE of a problem in which I wanted to replace some missing values for a specific set of observations in a DataFrame. It works with =, but not with the .=. Is this a bug? If not, can someone please cl…

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## [Is anyone familiar with MapD.com?](https://discourse.julialang.org/t/is-anyone-familiar-with-mapd-com/8038)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 2\
**Last updated:** [December 28, 2017, 2:43pm UTC](https://discourse.julialang.org/t/is-anyone-familiar-with-mapd-com/8038 "2017-12-28T14:43:42Z")

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Does anyone in the Julia community deal with MapD.com at all? It is a GPU database company and it uses LLVM which seems to be a natural fit for Julia.

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## [PyPlot: The Python package matplotlib.pyplot could not be found by pyimport](https://discourse.julialang.org/t/pyplot-the-python-package-matplotlib-pyplot-could-not-be-found-by-pyimport/8019)

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**Author:** [@v-i-s-h](https://discourse.julialang.org/u/v-i-s-h)\
**Replies:** 6\
**Last updated:** [December 28, 2017, 11:21am UTC](https://discourse.julialang.org/t/pyplot-the-python-package-matplotlib-pyplot-could-not-be-found-by-pyimport/8019 "2017-12-28T11:21:40Z")

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Hi, I have installed Julia 0.6.2 in my Ubuntu 16.04 and is using Conda for julia’s python distribution. julia\> versioninfo() Julia Version 0.6.2 Commit d386e40c17 (2017-12-13 18:08 UTC) Platform Info: OS: Linux (x86\_…

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## [Pandas.series.str.extract equivalent?](https://discourse.julialang.org/t/pandas-series-str-extract-equivalent/8016)

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**Author:** [@magrathean](https://discourse.julialang.org/u/magrathean)\
**Replies:** 2\
**Last updated:** [December 27, 2017, 5:18pm UTC](https://discourse.julialang.org/t/pandas-series-str-extract-equivalent/8016 "2017-12-27T17:18:01Z")

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How do I do the following pandas manipulation on a Julia Dataframe column: \>\>\> s = Series(\['a1', 'b2', 'c3'\]) \>\>\> s.str.extract('(?P\<letter\>\[ab\])(?P\<digit\>\\d)') letter digit 0 a 1 1 b 2 2 NaN Na…

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