# Latest

**URL:** https://discourse.julialang.org/latest.md?page=1933

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

**Page:** 1934

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## [Issues with JuliaPlots aspect ratio in 3d](https://discourse.julialang.org/t/issues-with-juliaplots-aspect-ratio-in-3d/28023)

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**Author:** [@Brad\_Hines](https://discourse.julialang.org/u/Brad_Hines)\
**Replies:** 0\
**Last updated:** [August 27, 2019, 3:19am UTC](https://discourse.julialang.org/t/issues-with-juliaplots-aspect-ratio-in-3d/28023 "2019-08-27T03:19:39Z")

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I am using plot(x,y,z,aspect\_ratio=:equal,…) Sometimes the aspect ratio “sticks” and sometimes it doesn’t. I am doing a day-long animation, and the aspect ratio jumps once every hour or two. For example, it’s fine at…

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## [How to interpolate in nested quotes?](https://discourse.julialang.org/t/how-to-interpolate-in-nested-quotes/27964)

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**Author:** [@tk3369](https://discourse.julialang.org/u/tk3369)\
**Replies:** 2\
**Last updated:** [August 27, 2019, 2:22am UTC](https://discourse.julialang.org/t/how-to-interpolate-in-nested-quotes/27964 "2019-08-27T02:22:17Z")

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Suppose that I have a variable v and I want to interpolate it into a nested quote expression. I tried double interpolation but it does not work properly… This is what I want: julia\> :( :( x = 1 ) ) |\> dump Expr head…

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## [Python \`collections.ChainMap\` equivalent?](https://discourse.julialang.org/t/python-collections-chainmap-equivalent/27990)

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**Author:** [@singularitti](https://discourse.julialang.org/u/singularitti)\
**Replies:** 4\
**Last updated:** [August 27, 2019, 12:51am UTC](https://discourse.julialang.org/t/python-collections-chainmap-equivalent/27990 "2019-08-27T00:51:30Z")

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Python’s collections.ChainMap class groups multiple dicts or other mappings together to create a single, updateable view. So it is suitable to let user-specified command-line arguments take precedence over environment va…

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## [How to compute hessian](https://discourse.julialang.org/t/how-to-compute-hessian/28012)

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**Author:** [@stochastic\_guy](https://discourse.julialang.org/u/stochastic_guy)\
**Replies:** 1\
**Last updated:** [August 26, 2019, 11:14pm UTC](https://discourse.julialang.org/t/how-to-compute-hessian/28012 "2019-08-26T23:14:08Z")

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New to Flux! I want to compute the gradient and hessian for this loss function. loss(x,y) = -sum(y.\*log.(model(x)) .- (1 .- y).\*log.(1 .- model(x))) \* 1 // size(y, 2) where model = Flux.Dense(in,out,σ) And how do yo…

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## [Keep default constructor when adding a zero-argument constructor](https://discourse.julialang.org/t/keep-default-constructor-when-adding-a-zero-argument-constructor/28014)

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**Author:** [@milesf](https://discourse.julialang.org/u/milesf)\
**Replies:** 6\
**Last updated:** [August 26, 2019, 10:50pm UTC](https://discourse.julialang.org/t/keep-default-constructor-when-adding-a-zero-argument-constructor/28014 "2019-08-26T22:50:45Z")

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If I add a zero-argument constructor Foo(), then I lose the ability to use the default constructor (e.g. Foo(1, 2)). This behavior is expected, and described in the documentation: If any inner constructor method is defin…

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## [ODE parameter estimation on a subset of the parameters](https://discourse.julialang.org/t/ode-parameter-estimation-on-a-subset-of-the-parameters/28013)

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**Author:** [@biona001](https://discourse.julialang.org/u/biona001)\
**Replies:** 2\
**Last updated:** [August 26, 2019, 10:45pm UTC](https://discourse.julialang.org/t/ode-parameter-estimation-on-a-subset-of-the-parameters/28013 "2019-08-26T22:45:43Z")

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Hello, I’m a differential equation newbie. I have an ODE model with 50 parameters and 10 compartments. I have data measured in only 3 compartments and I wish to fit 6 parameters. The 3 compartment problem is discussed h…

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## [How to use CSVFile as iterable?](https://discourse.julialang.org/t/how-to-use-csvfile-as-iterable/28005)

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**Author:** [@gabomgp](https://discourse.julialang.org/u/gabomgp)\
**Replies:** 3\
**Last updated:** [August 26, 2019, 10:25pm UTC](https://discourse.julialang.org/t/how-to-use-csvfile-as-iterable/28005 "2019-08-26T22:25:53Z")

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Hello again. I’m testing reading a large CSV using CSVFiles instead of CSV.jl because the CSV file is too large for CSV.jl on Windows. But I can not use the CSVFile as a iterable. I’m trying: function mylength(iter) …

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## [Use get! to get all elements in array](https://discourse.julialang.org/t/use-get-to-get-all-elements-in-array/28008)

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**Author:** [@elemenopeereste](https://discourse.julialang.org/u/elemenopeereste)\
**Replies:** 15\
**Last updated:** [August 26, 2019, 9:50pm UTC](https://discourse.julialang.org/t/use-get-to-get-all-elements-in-array/28008 "2019-08-26T21:50:16Z")

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Hi, I have question about function get!. So I have this lines: d=Dict("1"=\>\[1,11\], "2"=\>\[2\], "3"=\>\[3,13,33\]) a=\["2","3","4","5"\] t=Tuple(a) Can i use function “get” for my variable a and t? I mean get all elements whic…

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## [Trying to understand output of @code\_warntype](https://discourse.julialang.org/t/trying-to-understand-output-of-code-warntype/28000)

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**Author:** [@klaff](https://discourse.julialang.org/u/klaff)\
**Replies:** 4\
**Last updated:** [August 26, 2019, 7:07pm UTC](https://discourse.julialang.org/t/trying-to-understand-output-of-code-warntype/28000 "2019-08-26T19:07:39Z")

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In the output of @code\_warntype I’m getting a @\_6::Union{Nothing, Tuple{Int64,Int64}} that I don’t understand. Here’s a MWE # Monte Carlo tolerancing using Random, Distributions, LabelledArrays "named tuple of distri…

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## [\[blog post\] Implement You Own Source to Source AD in One day](https://discourse.julialang.org/t/blog-post-implement-you-own-source-to-source-ad-in-one-day/27017)

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**Author:** [@Roger-luo](https://discourse.julialang.org/u/Roger-luo)\
**Replies:** 2\
**Last updated:** [August 26, 2019, 8:38pm UTC](https://discourse.julialang.org/t/blog-post-implement-you-own-source-to-source-ad-in-one-day/27017 "2019-08-26T20:38:04Z")

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This is a blog post I wanted to write since last one :wink: http://blog.rogerluo.me/2019/07/27/yassad/ And I did it in JuliaCon2019 Hackthon with the help of @MikeInnes If you are interested in the internal of Zygote, …

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## [Usage of QR Factors](https://discourse.julialang.org/t/usage-of-qr-factors/27877)

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**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 12\
**Last updated:** [August 26, 2019, 5:40pm UTC](https://discourse.julialang.org/t/usage-of-qr-factors/27877 "2019-08-26T17:40:39Z")

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I’d like to compute QR factorisation Q, R = qr(A) followed by the operation Matrix(Q)' \* Y. As far as I can tell, Matrix(Q) allocates another matrix the same size as A which I’d like to avoid. Is there a way to perform …

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## [BigFloat wrong](https://discourse.julialang.org/t/bigfloat-wrong/27987)

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**Author:** [@mefi](https://discourse.julialang.org/u/mefi)\
**Replies:** 7\
**Last updated:** [August 26, 2019, 4:42pm UTC](https://discourse.julialang.org/t/bigfloat-wrong/27987 "2019-08-26T16:42:27Z")

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Why BigFloat(10^(1/4) is wrong? julia\> BigFloat(10^(1/4)) 1.778279410038922758729995621251873672008514404296875 exact: 1.77827941003892280122542119519… Thanks

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## [solving DiffEq on Complex Arrays](https://discourse.julialang.org/t/solving-diffeq-on-complex-arrays/24600)

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**Author:** [@balintradics](https://discourse.julialang.org/u/balintradics)\
**Replies:** 10\
**Last updated:** [August 26, 2019, 4:06pm UTC](https://discourse.julialang.org/t/solving-diffeq-on-complex-arrays/24600 "2019-08-26T16:06:58Z")

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Dear Julia, Following some examples, I am trying to solve a system ODE diff. eqs. on complex numbers, for which I have to use Complex array types. I have tried this from an example but it fails for me with Julia 1.0.3. …

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## [How to install Juliapro in Arch (based OS)](https://discourse.julialang.org/t/how-to-install-juliapro-in-arch-based-os/27710)

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**Author:** [@cagri](https://discourse.julialang.org/u/cagri)\
**Replies:** 7\
**Last updated:** [August 26, 2019, 1:58pm UTC](https://discourse.julialang.org/t/how-to-install-juliapro-in-arch-based-os/27710 "2019-08-26T13:58:58Z")

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Hi guys, Long time python machine learning (applied to finance) researcher here :slight\_smile: After being fascinated by speed of julia, I just wanted to deep dive into julia with Knet. However, I got a little confusion…

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## [JuMP v0.19.2 ⇒ v0.18.6](https://discourse.julialang.org/t/jump-v0-19-2-v0-18-6/27917)

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**Author:** [@raktim](https://discourse.julialang.org/u/raktim)\
**Replies:** 3\
**Last updated:** [August 26, 2019, 1:57pm UTC](https://discourse.julialang.org/t/jump-v0-19-2-v0-18-6/27917 "2019-08-26T13:57:09Z")

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Just installed Julia 1.2 along with JuMP and other packages. Did an update and noticed that JuMP was downgraded from version v0.19.2 ⇒ v0.18.6. Not sure why this is happening. Any clues?

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## [How to draw a folium.folium.Map object using pycall and Julia?](https://discourse.julialang.org/t/how-to-draw-a-folium-folium-map-object-using-pycall-and-julia/27965)

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**Author:** [@bsnyh](https://discourse.julialang.org/u/bsnyh)\
**Replies:** 6\
**Last updated:** [August 26, 2019, 1:45pm UTC](https://discourse.julialang.org/t/how-to-draw-a-folium-folium-map-object-using-pycall-and-julia/27965 "2019-08-26T13:45:30Z")

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I’m reading the tutorial following this link: OpenStreetMapX\_tutorial More specifically, the code I’m running is the following: using PyCall flm = pyimport("folium") matplotlib\_cm = pyimport("matplotlib.cm") matplotlib…

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## [The "Natural" Exponential "e" in Julia](https://discourse.julialang.org/t/the-natural-exponential-e-in-julia/27999)

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**Author:** [@Luigi\_Marongiu](https://discourse.julialang.org/u/Luigi_Marongiu)\
**Replies:** 1\
**Last updated:** [August 26, 2019, 1:42pm UTC](https://discourse.julialang.org/t/the-natural-exponential-e-in-julia/27999 "2019-08-26T13:42:14Z")

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Hello, how can i compute e^2x in Julia?

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## [JuMPeR installation problem with juliaPro-0.5.1.1](https://discourse.julialang.org/t/jumper-installation-problem-with-juliapro-0-5-1-1/2930)

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**Author:** [@Ayse\_Nur\_Arslan](https://discourse.julialang.org/u/Ayse_Nur_Arslan)\
**Replies:** 3\
**Last updated:** [August 26, 2019, 1:31pm UTC](https://discourse.julialang.org/t/jumper-installation-problem-with-juliapro-0-5-1-1/2930 "2019-08-26T13:31:33Z")

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Hello, I get the following error message when attempting to add the JuMPeR package using juliaPro-0.5.1.1 with the command Pkg.add(“JuMPeR”): ERROR: unsatisfiable package requirements detected: no feasible version cou…

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## [Handling various types of dependencies](https://discourse.julialang.org/t/handling-various-types-of-dependencies/27850)

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**Author:** [@ffevotte](https://discourse.julialang.org/u/ffevotte)\
**Replies:** 17\
**Last updated:** [August 26, 2019, 12:22pm UTC](https://discourse.julialang.org/t/handling-various-types-of-dependencies/27850 "2019-08-26T12:22:13Z")

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(I apologize in advance for the very long post) As I use Julia for ever more complex and complete projects, I seem to run into the following problem, where a single “project” contains lots of related code, which will be…

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## [Error requiring CuArrays from Flux](https://discourse.julialang.org/t/error-requiring-cuarrays-from-flux/27975)

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**Author:** [@Lyupinpin](https://discourse.julialang.org/u/Lyupinpin)\
**Replies:** 2\
**Last updated:** [August 26, 2019, 8:45am UTC](https://discourse.julialang.org/t/error-requiring-cuarrays-from-flux/27975 "2019-08-26T08:45:35Z")

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When I use the CuArrays, some warning always confuse me like, using CuArrays ┌ Warning: Error requiring CuArrays from Flux: │ LoadError: LoadError: UndefVarError: libcudnn not defined │ Stacktrace: │ \[1\] include at ./b…

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## [DifferentialEquations inside CUDA kernels](https://discourse.julialang.org/t/differentialequations-inside-cuda-kernels/27800)

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**Author:** [@fedoroff](https://discourse.julialang.org/u/fedoroff)\
**Replies:** 3\
**Last updated:** [August 26, 2019, 7:45am UTC](https://discourse.julialang.org/t/differentialequations-inside-cuda-kernels/27800 "2019-08-26T07:45:53Z")

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Hello, In my code I would like to use the integrator interface to DifferentialEquations inside CUDA kernels. Unfortunately, the type of integrators is not isbits and therefore can not be accessed inside the kernel. I wo…

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## [My experiences reading CSVs from the Fannie Mae datasets](https://discourse.julialang.org/t/my-experiences-reading-csvs-from-the-fannie-mae-datasets/8737)

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**Author:** [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Replies:** 62\
**Last updated:** [August 26, 2019, 7:41am UTC](https://discourse.julialang.org/t/my-experiences-reading-csvs-from-the-fannie-mae-datasets/8737 "2019-08-26T07:41:02Z")

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I am pretty excited about the Fannie Mae data being released so I tried to load the data into Julia. Unfortunately, it’s too much work trying to produce a MWE as being able to load large datasets is part of the point. Bu…

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## [Transposing player orders in a linear constraint](https://discourse.julialang.org/t/transposing-player-orders-in-a-linear-constraint/27945)

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**Author:** [@Saggaa](https://discourse.julialang.org/u/Saggaa)\
**Replies:** 3\
**Last updated:** [August 26, 2019, 7:30am UTC](https://discourse.julialang.org/t/transposing-player-orders-in-a-linear-constraint/27945 "2019-08-26T07:30:28Z")

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Hello everyone! I am currently learning Julia in college and i would need your expert help to better define a linear constraint in the frame of an assignment. Our professor is passionate about MLB and our assignment is…

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## [Common interface for chunked arrays?](https://discourse.julialang.org/t/common-interface-for-chunked-arrays/26009)

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**Author:** [@fabiangans](https://discourse.julialang.org/u/fabiangans)\
**Replies:** 10\
**Last updated:** [August 26, 2019, 6:56am UTC](https://discourse.julialang.org/t/common-interface-for-chunked-arrays/26009 "2019-08-26T06:56:16Z")

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Hi all, there is quite a zoo of data formats that allow you to store multidimensional arrays tiled into chunks, with or without compression. Examples are HDF5.jl, NetCDF.jl, Zarr.jl, or BigArrays.jl, maybe there will be…

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## [Nested getproperty requests](https://discourse.julialang.org/t/nested-getproperty-requests/27968)

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**Author:** [@ablaom](https://discourse.julialang.org/u/ablaom)\
**Replies:** 2\
**Last updated:** [August 26, 2019, 6:39am UTC](https://discourse.julialang.org/t/nested-getproperty-requests/27968 "2019-08-26T06:39:47Z")

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I have a use for accessing and setting nested properties of julia objects. To achieve this, I have the code below in a package. I have been reasonably accused of type piracy and wondered: (i) if others agree this is dang…

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## [Constraints for \`@generated\` function](https://discourse.julialang.org/t/constraints-for-generated-function/27967)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 2\
**Last updated:** [August 26, 2019, 6:26am UTC](https://discourse.julialang.org/t/constraints-for-generated-function/27967 "2019-08-26T06:26:01Z")

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It’s really not clear to me what is and isn’t allowed in a generated function. I get this error: ERROR: generated function body is not pure. this likely means it contains a closure or comprehension. Ok, but where’s t…

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## [Conditional indexing issue with float precision](https://discourse.julialang.org/t/conditional-indexing-issue-with-float-precision/27833)

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**Author:** [@drhouse82](https://discourse.julialang.org/u/drhouse82)\
**Replies:** 14\
**Last updated:** [August 26, 2019, 5:42am UTC](https://discourse.julialang.org/t/conditional-indexing-issue-with-float-precision/27833 "2019-08-26T05:42:18Z")

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Hi! I came accross a float-precision issue that I want to share and ask if there is a solution for my problem. I define an array of coordinates, an equally-sized array for the result, and I want to fill the second arra…

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## [Trouble creating new column in grouped object](https://discourse.julialang.org/t/trouble-creating-new-column-in-grouped-object/27982)

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**Author:** [@tlnagy](https://discourse.julialang.org/u/tlnagy)\
**Replies:** 1\
**Last updated:** [August 26, 2019, 5:15am UTC](https://discourse.julialang.org/t/trouble-creating-new-column-in-grouped-object/27982 "2019-08-26T05:15:28Z")

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using Query using DataFrames ex\_df = DataFrame(id = \[1,1,1,2,2,2,2\], trip= \["a", "a", "b", "a", "a", "b", "b"\], values=rand(7)) function consect(d) # 0 if consecutive values are the same, 1 otherwise Int.(view(…

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## [Help to generate code](https://discourse.julialang.org/t/help-to-generate-code/27935)

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**Author:** [@Tero\_Frondelius](https://discourse.julialang.org/u/Tero_Frondelius)\
**Replies:** 8\
**Last updated:** [August 26, 2019, 5:09am UTC](https://discourse.julialang.org/t/help-to-generate-code/27935 "2019-08-26T05:09:19Z")

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Dear community, I think I have a good use case for the learning of metaprogramming. I want to generate this code: for problem in get\_problems(analysis) for element in get\_elements(problem) …

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## [Truncate String](https://discourse.julialang.org/t/truncate-string/27978)

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**Author:** [@aplavin](https://discourse.julialang.org/u/aplavin)\
**Replies:** 13\
**Last updated:** [August 26, 2019, 4:09am UTC](https://discourse.julialang.org/t/truncate-string/27978 "2019-08-26T04:09:07Z")

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Hi! I’m having trouble with a simple problem of truncating strings to, say, 10 characters. As strings are not directly indexed with character indices, solutions s\[1:10\] (like in Python) or s\[1:min(length(s), 10)\] don’t w…

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