# Data

**URL:** https://discourse.julialang.org/c/domain/data/16.md?page=25

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**Page:** 26

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## [\[DataFrames Question\]: 0.20 performance benchmarks](https://discourse.julialang.org/t/dataframes-question-0-20-performance-benchmarks/34044)

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**Author:** [@anandj](https://discourse.julialang.org/u/anandj)\
**Replies:** 1\
**Last updated:** [March 4, 2020, 2:51pm UTC](https://discourse.julialang.org/t/dataframes-question-0-20-performance-benchmarks/34044 "2020-03-04T14:51:56Z")

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I was looking at the 0.20 release notes and noticed that performance was mentioned 5 times. I was wondering if anyone has done general benchmarking versus the prior version. Thanks

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## [Excel not recognize automatically generated CSV files using utf-8 encoding](https://discourse.julialang.org/t/excel-not-recognize-automatically-generated-csv-files-using-utf-8-encoding/35258)

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**Author:** [@JosephPollacco](https://discourse.julialang.org/u/JosephPollacco)\
**Replies:** 9\
**Last updated:** [March 1, 2020, 9:46pm UTC](https://discourse.julialang.org/t/excel-not-recognize-automatically-generated-csv-files-using-utf-8-encoding/35258 "2020-03-01T21:46:51Z")

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I generate utf-8 encoding output in Julia by using DelimitedFiles package. I would like students to be able to read the generated files automatically in EXCEL by using utf-8 encoding without going into the pain in Excel…

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## [\[ANN\] DBInterface.jl, MySQL.jl 1.0, and SQLite.jl 1.0](https://discourse.julialang.org/t/ann-dbinterface-jl-mysql-jl-1-0-and-sqlite-jl-1-0/34701)

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**Author:** [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Replies:** 5\
**Last updated:** [February 28, 2020, 3:42pm UTC](https://discourse.julialang.org/t/ann-dbinterface-jl-mysql-jl-1-0-and-sqlite-jl-1-0/34701 "2020-02-28T15:42:29Z")

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Sorry for all the posting lately, but I’ve been trying to coordinate a few 1.0 releases, so bear with me :sweat\_smile: This is the first official announcement of the new DBInterface.jl package, aiming to provide a stand…

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## [Replacing missing, really](https://discourse.julialang.org/t/replacing-missing-really/7952)

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**Author:** [@harven](https://discourse.julialang.org/u/harven)\
**Replies:** 8\
**Last updated:** [February 26, 2020, 11:20pm UTC](https://discourse.julialang.org/t/replacing-missing-really/7952 "2020-02-26T23:20:15Z")

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How can I replace the missing value in a dataframe by, say, 0? There is a Missings.replace function but it does not actually make the replacement. It builds a lazy data structure Missings.EachReplaceMissing{DataFrames.D…

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## [\[ANN\] New package: Strapping.jl](https://discourse.julialang.org/t/ann-new-package-strapping-jl/35038)

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**Author:** [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Replies:** 9\
**Last updated:** [February 25, 2020, 4:38am UTC](https://discourse.julialang.org/t/ann-new-package-strapping-jl/35038 "2020-02-25T04:38:04Z")

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I’ve been playing around with some “ORM” ideas for a bit in different ways, trying to find a good balance of “not-too-magical”, but still useful. I feel the design has finally come together well enough that I’d like to …

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## [Taking panel and temporal data seriously](https://discourse.julialang.org/t/taking-panel-and-temporal-data-seriously/35050)

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**Author:** [@Nosferican](https://discourse.julialang.org/u/Nosferican)\
**Replies:** 11\
**Last updated:** [February 23, 2020, 8:24pm UTC](https://discourse.julialang.org/t/taking-panel-and-temporal-data-seriously/35050 "2020-02-23T20:24:13Z")

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This discussion is about how to best implement a context for tabular data that generalizes to cross-sectional and temporal dimensions. For example, subject period value 1 1 0 1 2 3 1 3 …

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## [What is replacement for Not column selection in DataFrames (inverted index) in DataFrames v0.20.0?](https://discourse.julialang.org/t/what-is-replacement-for-not-column-selection-in-dataframes-inverted-index-in-dataframes-v0-20-0/34823)

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**Author:** [@js135005](https://discourse.julialang.org/u/js135005)\
**Replies:** 6\
**Last updated:** [February 18, 2020, 7:25pm UTC](https://discourse.julialang.org/t/what-is-replacement-for-not-column-selection-in-dataframes-inverted-index-in-dataframes-v0-20-0/34823 "2020-02-18T19:25:54Z")

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I was making extensive of the Not function for column selection in DataFrames. However this is deprecated in v0.20.0 and I haven’t yet found how to do the equivalent in the latest documentation. Indeed the DataFrames do…

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## [CSV.jl : how to specify the columns types when the total columns number is not known?](https://discourse.julialang.org/t/csv-jl-how-to-specify-the-columns-types-when-the-total-columns-number-is-not-known/34753)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 8\
**Last updated:** [February 18, 2020, 6:27am UTC](https://discourse.julialang.org/t/csv-jl-how-to-specify-the-columns-types-when-the-total-columns-number-is-not-known/34753 "2020-02-18T06:27:12Z")

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Hi, I have to read large tables, I don’t know the total number of columns of the tables but I do know that the first one contains strings and all the others are Float64. I can easily specify the type of the first one li…

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## [\[ANN\] Tables.jl 1.0 Release](https://discourse.julialang.org/t/ann-tables-jl-1-0-release/34505)

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**Author:** [@quinnj](https://discourse.julialang.org/u/quinnj)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 7:32am UTC](https://discourse.julialang.org/t/ann-tables-jl-1-0-release/34505 "2020-02-12T07:32:47Z")

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Hello all, A new 1.0 release was just registered in the General registry for the Tables.jl package. The API has matured well over the last 1.5 years (since 2018 JuliaCon hackathon!), and we felt like it was time for an…

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## [Equivalent of list() (R) in Julia](https://discourse.julialang.org/t/equivalent-of-list-r-in-julia/2860)

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**Author:** [@Jonathan\_Droxler](https://discourse.julialang.org/u/Jonathan_Droxler)\
**Replies:** 19\
**Last updated:** [January 30, 2020, 8:54pm UTC](https://discourse.julialang.org/t/equivalent-of-list-r-in-julia/2860 "2020-01-30T20:54:31Z")

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Dear all, Quite new in Julia (I’m already a big fan), I was wondering if there exist any data structure in Julia like “list()” in R. I search in the documentation, on google. Maybe I didn’t search well but I didn’t find…

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## [Timings for different groupby approaches](https://discourse.julialang.org/t/timings-for-different-groupby-approaches/33680)

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**Author:** [@venuur](https://discourse.julialang.org/u/venuur)\
**Replies:** 2\
**Last updated:** [January 23, 2020, 2:05am UTC](https://discourse.julialang.org/t/timings-for-different-groupby-approaches/33680 "2020-01-23T02:05:18Z")

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I am running some simulations at work, and I wanted to experiment with different approaches for performing a groupby and then running the simulation. The idea is to run a simulation of each group (identified by an id col…

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## [COM server for editing Excel files?](https://discourse.julialang.org/t/com-server-for-editing-excel-files/33672)

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**Author:** [@Iulian.Cioarca](https://discourse.julialang.org/u/Iulian.Cioarca)\
**Replies:** 0\
**Last updated:** [January 22, 2020, 7:10pm UTC](https://discourse.julialang.org/t/com-server-for-editing-excel-files/33672 "2020-01-22T19:10:54Z")

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I’m using GitHub - felipenoris/XLSX.jl: Excel file reader and writer for the Julia language. to write data into Excel files and it works great!Thanks,@felipenoris! I would also like to add some formatting(colors, borders…

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## [Create unit from string with Unitful.jl](https://discourse.julialang.org/t/create-unit-from-string-with-unitful-jl/33666)

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**Author:** [@moesphere](https://discourse.julialang.org/u/moesphere)\
**Replies:** 1\
**Last updated:** [January 22, 2020, 4:13pm UTC](https://discourse.julialang.org/t/create-unit-from-string-with-unitful-jl/33666 "2020-01-22T16:13:18Z")

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Is it possible to create a unit from a string with the Unitful.jl package at runtime without using eval? Something like this: unit\_str = "mol/L" unitful\_unit = unit(unit\_str) I only found u"..." and @u\_str, where stri…

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## [Will the new DataFrames be memory mapped?](https://discourse.julialang.org/t/will-the-new-dataframes-be-memory-mapped/1022)

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**Author:** [@Fred](https://discourse.julialang.org/u/Fred)\
**Replies:** 11\
**Last updated:** [January 20, 2020, 12:05am UTC](https://discourse.julialang.org/t/will-the-new-dataframes-be-memory-mapped/1022 "2020-01-20T00:05:16Z")

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In Julia, large Arrays can be memory mapped using the function Mmap.mmap(type::Type{Array{T, N}}, dims). But I have to work with large DataFrames (I have to keep columns and rows names and often NA values) in geno-trans…

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## [Make numbers from literature keep their reference](https://discourse.julialang.org/t/make-numbers-from-literature-keep-their-reference/33337)

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**Author:** [@feanor12](https://discourse.julialang.org/u/feanor12)\
**Replies:** 0\
**Last updated:** [January 14, 2020, 8:06am UTC](https://discourse.julialang.org/t/make-numbers-from-literature-keep-their-reference/33337 "2020-01-14T08:06:38Z")

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Julia is capable of defining new numbers, which can be used in conjunction with regular ones. To keep track of the source of the number(some material parameter) it should be possible to keep the DOI associated with it du…

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## [Does Python and Julia have the same file reading tools?](https://discourse.julialang.org/t/does-python-and-julia-have-the-same-file-reading-tools/29193)

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**Author:** [@Ahmed\_Salih](https://discourse.julialang.org/u/Ahmed_Salih)\
**Replies:** 14\
**Last updated:** [January 4, 2020, 6:52pm UTC](https://discourse.julialang.org/t/does-python-and-julia-have-the-same-file-reading-tools/29193 "2020-01-04T18:52:25Z")

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Hey folks I have spent some time in both Python and Julia to develop the same kind of function, a function which reads some binary files and import its data into an array. I have spent a lot of time tuning the Julia fun…

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## [SplitApplyCombine.jl \`group\` enhancements, reaches version 1.0.0](https://discourse.julialang.org/t/splitapplycombine-jl-group-enhancements-reaches-version-1-0-0/32675)

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**Author:** [@andyferris](https://discourse.julialang.org/u/andyferris)\
**Replies:** 1\
**Last updated:** [December 25, 2019, 3:13am UTC](https://discourse.julialang.org/t/splitapplycombine-jl-group-enhancements-reaches-version-1-0-0/32675 "2019-12-25T03:13:07Z")

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Merry Chirstmas everybody, Today I have released version 1.0.0 of SplitApplyCombine.jl, with the headline feature being that grouping functions have moved to returning a dictionary from Dictionaries.jl. On a personal n…

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## [A Julia-compatible alternative to zarr](https://discourse.julialang.org/t/a-julia-compatible-alternative-to-zarr/11842)

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**Author:** [@fabiangans](https://discourse.julialang.org/u/fabiangans)\
**Replies:** 19\
**Last updated:** [December 18, 2019, 8:17pm UTC](https://discourse.julialang.org/t/a-julia-compatible-alternative-to-zarr/11842 "2019-12-18T20:17:12Z")

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Dear Julia community, we are looking for a object-storage compatible file format for quite large dense N-dimensional arrays. Our project partners suggested this Zarr — zarr 2.13.6 documentation format, but there seems t…

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## [Group DataFrames by a function of a column](https://discourse.julialang.org/t/group-dataframes-by-a-function-of-a-column/32173)

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**Author:** [@robsmith11](https://discourse.julialang.org/u/robsmith11)\
**Replies:** 4\
**Last updated:** [December 11, 2019, 11:29pm UTC](https://discourse.julialang.org/t/group-dataframes-by-a-function-of-a-column/32173 "2019-12-11T23:29:22Z")

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I’m starting to use DataFrames more frequently and find myself often having to create a temporary table and column just to get a transformed column by which to group. For example: julia\> d=DataFrame(x=rand(10^6)); jul…

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## [DataFrame join error](https://discourse.julialang.org/t/dataframe-join-error/32141)

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**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 6\
**Last updated:** [December 11, 2019, 9:47am UTC](https://discourse.julialang.org/t/dataframe-join-error/32141 "2019-12-11T09:47:31Z")

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I have julia\> timeuse = join(people\[:, \[:idhh, :idpers, :gender\]\], timeuse; on = \[:idhh, :idpers\], kind = :inner) ERROR: DimensionMismatch("destination must have length equal to sums of concatenated vectors") Sta…

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## [How can I use TileDB from Julia?](https://discourse.julialang.org/t/how-can-i-use-tiledb-from-julia/18864)

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**Author:** [@Juan](https://discourse.julialang.org/u/Juan)\
**Replies:** 6\
**Last updated:** [November 18, 2019, 9:16pm UTC](https://discourse.julialang.org/t/how-can-i-use-tiledb-from-julia/18864 "2019-11-18T21:16:14Z")

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How can I use TileDB from Julia? Is there any port? I’ve searched on Julia observer but haven’t find anything? I’ve also searched on JuliaDB docs but haven’t found anything. I’m looking for a fast database to deal with…

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## [Help implementing Tables.jl interface](https://discourse.julialang.org/t/help-implementing-tables-jl-interface/31277)

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**Author:** [@randyzwitch](https://discourse.julialang.org/u/randyzwitch)\
**Replies:** 5\
**Last updated:** [November 19, 2019, 4:20pm UTC](https://discourse.julialang.org/t/help-implementing-tables-jl-interface/31277 "2019-11-19T16:20:49Z")

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PR with code here: https://github.com/omnisci/OmniSci.jl/pull/88/files I’m looking to modify some functions that take DataFrames as arguments to be more generic to take Tables, but I’m still not sure I understand why Ta…

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## [JuliaDB.flatten equivalent in DataFrames](https://discourse.julialang.org/t/juliadb-flatten-equivalent-in-dataframes/31048)

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**Author:** [@Dario\_Sarra](https://discourse.julialang.org/u/Dario_Sarra)\
**Replies:** 7\
**Last updated:** [November 14, 2019, 1:01pm UTC](https://discourse.julialang.org/t/juliadb-flatten-equivalent-in-dataframes/31048 "2019-11-14T13:01:28Z")

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Hello, is there a way to produce in DataFrames the same result of JuliaDB.flatten using DataFrames using JuliaDB d1 = DataFrame(cat = \["a","b"\], vec = \[\[1,2\],\[3,4\]\]) t1 = table(d1) t2 = flatten(t1,:vec)…

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## [Implement case\_when in Queryverse](https://discourse.julialang.org/t/implement-case-when-in-queryverse/30986)

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**Author:** [@pradeip1](https://discourse.julialang.org/u/pradeip1)\
**Replies:** 8\
**Last updated:** [November 13, 2019, 1:30pm UTC](https://discourse.julialang.org/t/implement-case-when-in-queryverse/30986 "2019-11-13T13:30:53Z")

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Can we implement case\_when in Julia? I am trying to achieve this R code using Queryverse in Julia Example in R: mutate(TIME = case\_when(TIME == 0 ~ 95.9, TIME == 0.08 ~ 96.08, TIME == 0.25 ~ 96.25, TIME == 0.50 ~ 9…

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## [Mutate a new variable with row numbers](https://discourse.julialang.org/t/mutate-a-new-variable-with-row-numbers/30985)

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**Author:** [@pradeip1](https://discourse.julialang.org/u/pradeip1)\
**Replies:** 4\
**Last updated:** [November 12, 2019, 10:41am UTC](https://discourse.julialang.org/t/mutate-a-new-variable-with-row-numbers/30985 "2019-11-12T10:41:48Z")

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how to add a row number using Queryverse in Julia? for example in R I simply use ID = row\_number()

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## [Getting error while using CurricularAnalytics](https://discourse.julialang.org/t/getting-error-while-using-curricularanalytics/30389)

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**Author:** [@Gaurav\_Sharma](https://discourse.julialang.org/u/Gaurav_Sharma)\
**Replies:** 2\
**Last updated:** [October 29, 2019, 6:55pm UTC](https://discourse.julialang.org/t/getting-error-while-using-curricularanalytics/30389 "2019-10-29T18:55:43Z")

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Version of Julia: “1.3.0-rc4.1” CurricularAnalytics v0.6.0 “”" import Pkg Pkg.add(“CurricularAnalytics”) using CurricularAnalytics Info: Precompiling CurricularAnalytics \[593ffa3d-269e-5d81-88bc-c3b6809c35a6\] └ @ …

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## [How to add metadata info to a DataFrame?](https://discourse.julialang.org/t/how-to-add-metadata-info-to-a-dataframe/11168)

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**Author:** [@gcalderone](https://discourse.julialang.org/u/gcalderone)\
**Replies:** 96\
**Last updated:** [October 26, 2019, 2:57am UTC](https://discourse.julialang.org/t/how-to-add-metadata-info-to-a-dataframe/11168 "2019-10-26T02:57:26Z")

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Storing both data and metadata in the same object or container is a very common approach in many research fields, and it has proven to be very successful in (for instance) astronomy where a few standards had been officia…

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## [Tables.jl win!](https://discourse.julialang.org/t/tables-jl-win/30312)

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**Author:** [@jkbest2](https://discourse.julialang.org/u/jkbest2)\
**Replies:** 0\
**Last updated:** [October 25, 2019, 5:45pm UTC](https://discourse.julialang.org/t/tables-jl-win/30312 "2019-10-25T17:45:48Z")

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One of my projects (originally written in the v0.6 days) generates a Vector of structs as its output. In the past I would’ve converted it to a DataFrame or similar with a lot of getfield broadcasts, but I was delighted t…

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## [Julia-Gumbo-webscraping](https://discourse.julialang.org/t/julia-gumbo-webscraping/30203)

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**Author:** [@Anil\_Mathews](https://discourse.julialang.org/u/Anil_Mathews)\
**Replies:** 16\
**Last updated:** [October 24, 2019, 1:54pm UTC](https://discourse.julialang.org/t/julia-gumbo-webscraping/30203 "2019-10-24T13:54:16Z")

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Is it possible to convert structure type to julia string type. i have scraped some data from website with Gumbo.jl and i want to push this data to a Array but when i do that i get this error:Cannot convert an object of …

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## [Pandas's fast isin() equivalent in Julia DataFrame or IndexedTable or anything else](https://discourse.julialang.org/t/pandass-fast-isin-equivalent-in-julia-dataframe-or-indexedtable-or-anything-else/30073)

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**Author:** [@Sijun](https://discourse.julialang.org/u/Sijun)\
**Replies:** 5\
**Last updated:** [October 19, 2019, 11:05am UTC](https://discourse.julialang.org/t/pandass-fast-isin-equivalent-in-julia-dataframe-or-indexedtable-or-anything-else/30073 "2019-10-19T11:05:13Z")

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Python Pandas DataFrame’s isin() is really fast. for example: import numpy as np import pandas as pd df = pd.DataFrame({"x": np.random.randint(1,100, size=(10\*\*6,)), "y": np.random.randint(50,149, size=…

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