# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=551

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**Page:** 552

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## [Understanding recipes in Plots.jl](https://discourse.julialang.org/t/understanding-recipes-in-plots-jl/1912)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 24\
**Last updated:** [October 17, 2017, 7:43pm UTC](https://discourse.julialang.org/t/understanding-recipes-in-plots-jl/1912 "2017-10-17T19:43:33Z")

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I am trying to define a recipe for my package that generates a plot out of an image. Consider the simplified example below: # somewhere in my package... using RecipesBase @recipe function plotfoo(A::AbstractArray) x…

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## [Best practice for streaming a template file with replaced strings](https://discourse.julialang.org/t/best-practice-for-streaming-a-template-file-with-replaced-strings/6469)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 6\
**Last updated:** [October 17, 2017, 5:29pm UTC](https://discourse.julialang.org/t/best-practice-for-streaming-a-template-file-with-replaced-strings/6469 "2017-10-17T17:29:43Z")

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I have a template file with a few placeholders. I want to replace the placeholders with actual values and pipe the result forward. Currently I read the whole file, find all occurrences of the placeholders and replace th…

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## [How to use aggregate\_vec to create two output columnd JuliaDB.jl & IndexedTables?](https://discourse.julialang.org/t/how-to-use-aggregate-vec-to-create-two-output-columnd-juliadb-jl-indexedtables/6497)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 5\
**Last updated:** [October 17, 2017, 4:44pm UTC](https://discourse.julialang.org/t/how-to-use-aggregate-vec-to-create-two-output-columnd-juliadb-jl-indexedtables/6497 "2017-10-17T16:44:24Z")

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Please see my MVE for creating the data needed for this question using Distributions, PooledArrays N=Int64(2e7); K=100; pool = \[@sprintf "id%03d" k for k in 1:K\] function randstrarray(pool, N) PooledArray(PooledA…

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## [Time limit with GLPK](https://discourse.julialang.org/t/time-limit-with-glpk/6263)

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**Author:** [@XavierG](https://discourse.julialang.org/u/XavierG)\
**Replies:** 3\
**Last updated:** [October 17, 2017, 1:04pm UTC](https://discourse.julialang.org/t/time-limit-with-glpk/6263 "2017-10-17T13:04:06Z")

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Hi all, GLPK proposes an option to stop the (MIP) solver after an elapsed time: TmLim (TmLim=value). Probably I am invoking the option in a wrong manner because it is not recognized (WARNING: Ignored option: TmLim). Som…

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## [Reproducing Rump’s example](https://discourse.julialang.org/t/reproducing-rump-s-example/6473)

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**Author:** [@Jorispilot](https://discourse.julialang.org/u/Jorispilot)\
**Replies:** 7\
**Last updated:** [October 17, 2017, 11:02am UTC](https://discourse.julialang.org/t/reproducing-rump-s-example/6473 "2017-10-17T11:02:58Z")

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Hi everyone. New to Julia, I try to reproduce a tricky case study of floating-point arithmetic with the BigFloat module: the “Rump’s example” described in https://tel.archives-ouvertes.fr/tel-00657843v2/document page …

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## [Exploiting structure in KKT system using JuMP](https://discourse.julialang.org/t/exploiting-structure-in-kkt-system-using-jump/6456)

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**Author:** [@juliohm](https://discourse.julialang.org/u/juliohm)\
**Replies:** 6\
**Last updated:** [October 16, 2017, 6:30pm UTC](https://discourse.julialang.org/t/exploiting-structure-in-kkt-system-using-jump/6456 "2017-10-16T18:30:16Z")

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Suppose I have a LP in which objective and constraints only involve neighboring variables. That is, I have a matrix variable X and each of my expressions only involve the variables X\[i,j\], X\[i-1,j\], X\[i+1,j\], X\[i,j-1\], X…

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## [Stack overflow in DataFrames group by](https://discourse.julialang.org/t/stack-overflow-in-dataframes-group-by/6357)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 16\
**Last updated:** [October 15, 2017, 5:28pm UTC](https://discourse.julialang.org/t/stack-overflow-in-dataframes-group-by/6357 "2017-10-15T17:28:35Z")

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I have a million row data frame and I am running groupby on a column of strings: by(df, :col) do sdf DataFrame(n=size(sdf,1)) end and I get the following StackOverflowError ERROR: LoadError: StackOverflowError: St…

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## [\`Nulls.skip\` is very slow](https://discourse.julialang.org/t/nulls-skip-is-very-slow/6351)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 4\
**Last updated:** [October 15, 2017, 12:40pm UTC](https://discourse.julialang.org/t/nulls-skip-is-very-slow/6351 "2017-10-15T12:40:46Z")

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Please excuse how rough this example is (but I think it is essentially correct) using Nulls using BenchmarkTools const N = 10^7 const n = 10^5 A = convert(Vector{Union{Int64,Null}}, rand(Int64, N)) …

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## [Which are efficient data structures for querying data by name?](https://discourse.julialang.org/t/which-are-efficient-data-structures-for-querying-data-by-name/6285)

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**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [October 14, 2017, 12:08pm UTC](https://discourse.julialang.org/t/which-are-efficient-data-structures-for-querying-data-by-name/6285 "2017-10-14T12:08:34Z")

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Hello, while I guess standard Array{T,n} are the most efficient data structures for positional access, I have often the need to access data by some keys. I am currently using DataFrames to access this data, using eithe…

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## [Jump heuristic isn't working (says infeasible)](https://discourse.julialang.org/t/jump-heuristic-isnt-working-says-infeasible/6428)

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**Author:** [@Wikunia](https://discourse.julialang.org/u/Wikunia)\
**Replies:** 0\
**Last updated:** [October 13, 2017, 7:33pm UTC](https://discourse.julialang.org/t/jump-heuristic-isnt-working-says-infeasible/6428 "2017-10-13T19:33:42Z")

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I have the following facility location model: m = Model(solver=GLPKSolverMIP()) @variable(m, sf\[1:N\], Bin) @variable(m, cf\[c=1:M,f=1:N\], Bin) @objective(m, Min, dot(f\_s,sf)+sum(cf\[c=j,f=i\]\*euclidean(c\_pos\[j\],f\_pos\[i\]) f…

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## [Momentum methods in Optim - do you use them?](https://discourse.julialang.org/t/momentum-methods-in-optim-do-you-use-them/6416)

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**Author:** [@pkofod](https://discourse.julialang.org/u/pkofod)\
**Replies:** 11\
**Last updated:** [October 13, 2017, 3:56pm UTC](https://discourse.julialang.org/t/momentum-methods-in-optim-do-you-use-them/6416 "2017-10-13T15:56:36Z")

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As the title suggests, I’m currently wondering if Accelerated Gradient Descent and Momentum Gradient Descent should be (re)moved from Optim. “Momentum methods” certainly have their use, and machine learning seems to hav…

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## [Problem with adding a column](https://discourse.julialang.org/t/problem-with-adding-a-column/4243)

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**Author:** [@mposs](https://discourse.julialang.org/u/mposs)\
**Replies:** 4\
**Last updated:** [October 12, 2017, 7:08pm UTC](https://discourse.julialang.org/t/problem-with-adding-a-column/4243 "2017-10-12T19:08:14Z")

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I’m trying to add an anonymous variable to two constraints but I get an error. using JuMP m = Model() @constraint(m, con1, 0 \<= 1) @constraint(m, con2, 0 \<= 1) constrrefs = Vector{ConstraintRef}(0) push!(constrrefs,con1…

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## [Integrating Leaflet into Julia](https://discourse.julialang.org/t/integrating-leaflet-into-julia/6411)

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**Author:** [@Balinus](https://discourse.julialang.org/u/Balinus)\
**Replies:** 2\
**Last updated:** [October 12, 2017, 6:28pm UTC](https://discourse.julialang.org/t/integrating-leaflet-into-julia/6411 "2017-10-12T18:28:02Z")

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Hello! I’m currently testing leaflet.js through the Python Folium package through Julia (that’s a lot of “through”). I find that the maps are really nice and I’m looking to use that framework into my package (ClimateToo…

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## [Enumerate(dict) behavior](https://discourse.julialang.org/t/enumerate-dict-behavior/5312)

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**Author:** [@sambitdash](https://discourse.julialang.org/u/sambitdash)\
**Replies:** 10\
**Last updated:** [October 11, 2017, 3:12am UTC](https://discourse.julialang.org/t/enumerate-dict-behavior/5312 "2017-10-11T03:12:00Z")

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Hi All, enumerate(iter) behavior enumerates over an index and dataItem to the associated index. For associative containers like Dict one would believe the natural iteration will be over named indexes which is the (key, …

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## [\`InexactError\` when plotting \`DateTime\` in Plots.jl](https://discourse.julialang.org/t/inexacterror-when-plotting-datetime-in-plots-jl/6379)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 3\
**Last updated:** [October 10, 2017, 6:04pm UTC](https://discourse.julialang.org/t/inexacterror-when-plotting-datetime-in-plots-jl/6379 "2017-10-10T18:04:21Z")

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When attempting to plot a histogram of DateTime I get the following error ERROR: LoadError: InexactError() Stacktrace: \[1\] convert(::Type{Int64}, ::Float64) at ./float.jl:679 \[2\] UTM at ./dates/types.jl:74 \[inlined\] …

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## [Leaky relu with Flux](https://discourse.julialang.org/t/leaky-relu-with-flux/6377)

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**Author:** [@skariel](https://discourse.julialang.org/u/skariel)\
**Replies:** 1\
**Last updated:** [October 10, 2017, 1:09pm UTC](https://discourse.julialang.org/t/leaky-relu-with-flux/6377 "2017-10-10T13:09:03Z")

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Any ideas how to implement LeakyRelu, getting a no method matching error on isless. Also I had to implement my own std function: Thanks! mystd(x) = sqrt(sum((x-mean(x)).^2)/(length(x)-1)) lrelu(x) = isless(x,0.0) ? 0.…

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## [Get siginificance of main fixed category effects in mixed linear model with MixedModels.jl](https://discourse.julialang.org/t/get-siginificance-of-main-fixed-category-effects-in-mixed-linear-model-with-mixedmodels-jl/6268)

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**Author:** [@ksmet1977](https://discourse.julialang.org/u/ksmet1977)\
**Replies:** 7\
**Last updated:** [October 10, 2017, 12:31pm UTC](https://discourse.julialang.org/t/get-siginificance-of-main-fixed-category-effects-in-mixed-linear-model-with-mixedmodels-jl/6268 "2017-10-10T12:31:54Z")

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Hi group, I have a dataframe of \>10000 rows of repeated measurements on 25 subjects (OB) on 3 categorical factors (QF,B,PA) and 1 continuous (CCT) factor. The first few lines look like this: │ Row │ OB │ QF │ BG │ …

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## [Triangulated surfaces in GR: ray-tracing](https://discourse.julialang.org/t/triangulated-surfaces-in-gr-ray-tracing/6348)

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**Author:** [@sswatson](https://discourse.julialang.org/u/sswatson)\
**Replies:** 1\
**Last updated:** [October 9, 2017, 2:41pm UTC](https://discourse.julialang.org/t/triangulated-surfaces-in-gr-ray-tracing/6348 "2017-10-09T14:41:00Z")

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I’m looking to use GR along with Interact.jl for a 3D visualization in IJulia, and I noticed that GR.trisurface seems to have some difficulties with overlapping polygons (as matplotlib does). Is there currently a way to…

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## [ANN: Bloomie.jl (Bloomberg BLPAPI wrapper)](https://discourse.julialang.org/t/ann-bloomie-jl-bloomberg-blpapi-wrapper/6347)

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**Author:** [@ungil](https://discourse.julialang.org/u/ungil)\
**Replies:** 0\
**Last updated:** [October 9, 2017, 1:52pm UTC](https://discourse.julialang.org/t/ann-bloomie-jl-bloomberg-blpapi-wrapper/6347 "2017-10-09T13:52:56Z")

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https://github.com/ungil/Bloomie.jl The package has been only lightly tested, it was written mostly as an exercise to try Julia and its FFI.

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## [Read(“count\_heads.jl”, String) conversion error](https://discourse.julialang.org/t/read-count-heads-jl-string-conversion-error/6253)

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**Author:** [@EconometricsBySimula](https://discourse.julialang.org/u/EconometricsBySimula)\
**Replies:** 8\
**Last updated:** [October 9, 2017, 3:43am UTC](https://discourse.julialang.org/t/read-count-heads-jl-string-conversion-error/6253 "2017-10-09T03:43:36Z")

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I am going through Parallel Loops and Maps and I am seeming to have difficulty with even accessing the file count\_heads.jl I saved it in my working directory function count\_heads(n) c::Int = 0 for i = 1:n c += rand…

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## [Run model runs in a parallel for loop in julia](https://discourse.julialang.org/t/run-model-runs-in-a-parallel-for-loop-in-julia/6326)

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**Author:** [@Simon\_Besnard](https://discourse.julialang.org/u/Simon_Besnard)\
**Replies:** 2\
**Last updated:** [October 8, 2017, 6:56pm UTC](https://discourse.julialang.org/t/run-model-runs-in-a-parallel-for-loop-in-julia/6326 "2017-10-08T18:56:36Z")

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I am trying to parallelize the code below. The idea is to run several model runs in parallel and push their output in to a single dataframe (i.e. dout). The code I have created works with no parrallelisation so far. Howe…

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## [Exact linear algebra](https://discourse.julialang.org/t/exact-linear-algebra/6167)

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**Author:** [@tkluck](https://discourse.julialang.org/u/tkluck)\
**Replies:** 10\
**Last updated:** [October 8, 2017, 4:06pm UTC](https://discourse.julialang.org/t/exact-linear-algebra/6167 "2017-10-08T16:06:54Z")

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Hey all! I’ve been using Julia for algebra computations (think polynomial rings, ideals, Groebner basis, etc). Linear algebra is often fundamental to that, and Julia seems very suited to that! There’s a few choices in …

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## [How to get DTable column names?](https://discourse.julialang.org/t/how-to-get-dtable-column-names/6307)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 1\
**Last updated:** [October 7, 2017, 12:26pm UTC](https://discourse.julialang.org/t/how-to-get-dtable-column-names/6307 "2017-10-07T12:26:19Z")

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I loaded a set of CSV using JuliaDB.jl’s loadfiles.And I got a DTable, but there does not appear to be a function that can tell me the names of the columns. There is a names functions for DataFrames it feels natural to …

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## [One stop shop for benchmark optimization problems?](https://discourse.julialang.org/t/one-stop-shop-for-benchmark-optimization-problems/6257)

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**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 9\
**Last updated:** [October 6, 2017, 11:40pm UTC](https://discourse.julialang.org/t/one-stop-shop-for-benchmark-optimization-problems/6257 "2017-10-06T23:40:41Z")

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Wouldn’t it be nice to have a single package in Julia hosting benchmark optimization problems for different classes of optimization to make it easier for solver developers to test their solvers and benchmark them? The pr…

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## [Special method for Eigenvectors of Sparse+Hermitian+Complex matrix?](https://discourse.julialang.org/t/special-method-for-eigenvectors-of-sparse-hermitian-complex-matrix/6233)

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**Author:** [@Datseris](https://discourse.julialang.org/u/Datseris)\
**Replies:** 19\
**Last updated:** [October 6, 2017, 12:36pm UTC](https://discourse.julialang.org/t/special-method-for-eigenvectors-of-sparse-hermitian-complex-matrix/6233 "2017-10-06T12:36:44Z")

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After searching Google, the docs and discourse, I did not find any reference to any method that finds eigenvecs and eigenvals of Sparse, Hermitian and Complex matrices. I found a method specialized for Real and Symmetric…

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## [Parameters optimization profiles](https://discourse.julialang.org/t/parameters-optimization-profiles/6141)

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**Author:** [@ivborissov](https://discourse.julialang.org/u/ivborissov)\
**Replies:** 3\
**Last updated:** [October 6, 2017, 10:53am UTC](https://discourse.julialang.org/t/parameters-optimization-profiles/6141 "2017-10-06T10:53:27Z")

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Hi, has anyone solved the following optimization problem: I am estimating ODE parameters (using NLopt) like param1,param2,param3 and I want to create “profiles” of each parameter. It means estimate param2 and param3 for …

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## [HDF5: Writing to a Compound Table](https://discourse.julialang.org/t/hdf5-writing-to-a-compound-table/6265)

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**Author:** [@Jeremy](https://discourse.julialang.org/u/Jeremy)\
**Replies:** 0\
**Last updated:** [October 5, 2017, 3:46pm UTC](https://discourse.julialang.org/t/hdf5-writing-to-a-compound-table/6265 "2017-10-05T15:46:47Z")

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How do I write data to a compound table in an HDF5 file? I’ve figured out how to create the table. src = "/home/user/Desktop/hdf5\_test.h5" h5open(src, "w") do file cols = \["foo","bar","blah","blahblahblah"\] memtype\_…

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## [Reverting to earlier CUDA - version report stubborn](https://discourse.julialang.org/t/reverting-to-earlier-cuda-version-report-stubborn/6247)

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**Author:** [@Colin\_Beckingham](https://discourse.julialang.org/u/Colin_Beckingham)\
**Replies:** 3\
**Last updated:** [October 5, 2017, 9:57am UTC](https://discourse.julialang.org/t/reverting-to-earlier-cuda-version-report-stubborn/6247 "2017-10-05T09:57:53Z")

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I’m trying to revert versions of CUDA from 9 to 7. The removal of 9 and install of 7 seems to have gone ok but CUDAdrv.version() is still reporting v"9.0.0". I have Pkg.rm() twice each for CUDAdrv and CUDAnative and cle…

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## [Binary CUDA dependency](https://discourse.julialang.org/t/binary-cuda-dependency/6226)

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**Author:** [@una-dinosauria](https://discourse.julialang.org/u/una-dinosauria)\
**Replies:** 8\
**Last updated:** [October 4, 2017, 7:06am UTC](https://discourse.julialang.org/t/binary-cuda-dependency/6226 "2017-10-04T07:06:02Z")

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I’m in the process of building a Julia package which uses some custom CUDA kernels that I wrote a few years ago. I want to provide these CUDA binaries with the package, and have them compiled using BinDeps.jl. I’m follo…

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## [SQLAlchemy.jl Resurrected](https://discourse.julialang.org/t/sqlalchemy-jl-resurrected/6206)

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**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 2\
**Last updated:** [October 3, 2017, 2:03pm UTC](https://discourse.julialang.org/t/sqlalchemy-jl-resurrected/6206 "2017-10-03T14:03:55Z")

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As complaining about SQL is one of my favorite pastimes, I’ve found that it made my life a whole lot easier to make SQLAlchemy.jl work again. So much work has been put into sqlalchemy that it seems crazy not to use it. …

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