https://kotlinlang.org logo
Channels
100daysofcode
100daysofkotlin
100daysofkotlin-2021
advent-of-code
aem
ai
alexa
algeria
algolialibraries
amsterdam
android
android-architecture
android-databinding
android-studio
androidgithubprojects
androidthings
androidx
androidx-xprocessing
anime
anko
announcements
apollo-kotlin
appintro
arabic
argentina
arkenv
arksemdevteam
armenia
arrow
arrow-contributors
arrow-meta
ass
atlanta
atm17
atrium
austin
australia
austria
awesome-kotlin
ballast
bangladesh
barcelona
bayarea
bazel
beepiz-libraries
belgium
benchmarks
berlin
big-data
books
boston
brazil
brikk
budapest
build
build-tools
bulgaria
bydgoszcz
cambodia
canada
carrat
carrat-dev
carrat-feed
chicago
chile
china
chucker
cincinnati-user-group
cli
clikt
cloudfoundry
cn
cobalt
code-coverage
codeforces
codemash-precompiler
codereview
codingame
codingconventions
coimbatore
collaborations
colombia
colorado
communities
competitive-programming
competitivecoding
compiler
compose
compose-android
compose-desktop
compose-hiring
compose-ios
compose-mp
compose-ui-showcase
compose-wear
compose-web
confetti
connect-audit-events
corda
cork
coroutines
couchbase
coursera
croatia
cryptography
cscenter-course-2016
cucumber-bdd
cyprus
czech
dagger
data2viz
databinding
datascience
dckotlin
debugging
decompose
decouple
denmark
deprecated
detekt
detekt-hint
dev-core
dfw
docs-revamped
dokka
domain-driven-design
doodle
dsl
dublin
dutch
eap
eclipse
ecuador
edinburgh
education
effective-kotlin
effectivekotlin
emacs
embedded-kotlin
estatik
event21-community-content
events
exposed
failgood
fb-internal-demo
feed
firebase
flow
fluid-libraries
forkhandles
forum
fosdem
fp-in-kotlin
framework-elide
freenode
french
fritz2
fuchsia
functional
funktionale
gamedev
ge-kotlin
general-advice
georgia
geospatial
german-lang
getting-started
github-workflows-kt
glance
godot-kotlin
google-io
gradle
graphic
graphkool
graphql
graphql-kotlin
graviton-browser
greece
grpc
gsoc
gui
hackathons
hacktoberfest
hamburg
hamkrest
helios
helsinki
hexagon
hibernate
hikari-cp
hire-me
hiring
hiring-french
hongkong
hoplite
http4k
hungary
hyderabad
image-processing
india
indonesia
inkremental
intellij
intellij-plugins
intellij-tricks
internships
introduce-yourself
io
ios
iran
israel
istanbulcoders
italian
jackson-kotlin
jadx
japanese
jasync-sql
java-to-kotlin-refactoring
javadevelopers
javafx
javalin
javascript
jdbi
jhipster-kotlin
jobsworldwide
jpa
jshdq
juul-libraries
jvm-ir-backend-feedback
jxadapter
k2-early-adopters
kaal
kafka
kakao
kalasim
kapt
karachi
karg
karlsruhe
kash_shell
kaskade
kbuild
kdbc
kgen-doc-tools
kgraphql
kinta
klaxon
klock
kloudformation
kmdc
kmm-español
kmongo
knbt
knote
koalaql
koans
kobalt
kobweb
kodein
kodex
kohesive
koin
koin-dev
komapper
kondor-json
kong
kontent
kontributors
korau
korean
korge
korim
korio
korlibs
korte
kotest
kotest-contributors
kotless
kotlick
kotlin-asia
kotlin-beam
kotlin-by-example
kotlin-csv
kotlin-data-storage
kotlin-foundation
kotlin-fuel
kotlin-in-action
kotlin-inject
kotlin-latam
kotlin-logging
kotlin-multiplatform-contest
kotlin-mumbai
kotlin-native
kotlin-pakistan
kotlin-plugin
kotlin-pune
kotlin-roadmap
kotlin-samples
kotlin-sap
kotlin-serbia
kotlin-spark
kotlin-szeged
kotlin-website
kotlinacademy
kotlinbot
kotlinconf
kotlindl
kotlinforbeginners
kotlingforbeginners
kotlinlondon
kotlinmad
kotlinprogrammers
kotlinsu
kotlintest
kotlintest-devs
kotlintlv
kotlinultimatechallenge
kotlinx-datetime
kotlinx-files
kotlinx-html
kotrix
kotson
kovenant
kprompt
kraph
krawler
kroto-plus
ksp
ktcc
ktfmt
ktlint
ktor
ktp
kubed
kug-leads
kug-torino
kvision
kweb
lambdaworld_cadiz
lanark
language-evolution
language-proposals
latvia
leakcanary
leedskotlinusergroup
lets-have-fun
libgdx
libkgd
library-development
lincheck
linkeddata
lithuania
london
losangeles
lottie
love
lychee
macedonia
machinelearningbawas
madrid
malaysia
mathematics
meetkotlin
memes
meta
metro-detroit
mexico
miami
micronaut
minnesota
minutest
mirror
mockk
moko
moldova
monsterpuzzle
montreal
moonbean
morocco
motionlayout
mpapt
mu
multiplatform
mumbai
munich
mvikotlin
mvrx
myndocs-oauth2-server
naming
navigation-architecture-component
nepal
new-mexico
new-zealand
newname
nigeria
nodejs
norway
npm-publish
nyc
oceania
ohio-kotlin-users
oldenburg
oolong
opensource
orbit-mvi
osgi
otpisani
package-search
pakistan
panamá
pattern-matching
pbandk
pdx
peru
philippines
phoenix
pinoy
pocketgitclient
polish
popkorn
portugal
practical-functional-programming
proguard
prozis-android-backup
pyhsikal
python
python-contributors
quasar
random
re
react
reaktive
realm
realworldkotlin
reductor
reduks
redux
redux-kotlin
refactoring-to-kotlin
reflect
refreshversions
reports
result
rethink
revolver
rhein-main
rocksdb
romania
room
rpi-pico
rsocket
russian
russian_feed
russian-kotlinasfirst
rx
rxjava
san-diego
science
scotland
scrcast
scrimage
script
scripting
seattle
serialization
server
sg-user-group
singapore
skia-wasm-interop-temp
skrape-it
slovak
snake
sofl-user-group
southafrica
spacemacs
spain
spanish
speaking
spek
spin
splitties
spotify-mobius
spring
spring-security
squarelibraries
stackoverflow
stacks
stayhungrystayfoolish
stdlib
stlouis
strife-discord-lib
strikt
students
stuttgart
sudan
swagger-gradle-codegen
swarm
sweden
swing
swiss-user-group
switzerland
talking-kotlin
tallinn
tampa
teamcity
tegal
tempe
tensorflow
terminal
test
testing
testtestest
texas
tgbotapi
thailand
tornadofx
touchlab-tools
training
tricity-kotlin-user-group
trójmiasto
truth
tunisia
turkey
turkiye
twitter-feed
uae
udacityindia
uk
ukrainian
uniflow
unkonf
uruguay
utah
uuid
vancouver
vankotlin
vertx
videos
vienna
vietnam
vim
vkug
vuejs
web-mpp
webassembly
webrtc
wimix_sentry
wwdc
zircon
Powered by
Title
b

bjonnh

11/08/2019, 11:16 PM
@jimn Wait is that a way to read python dataframes in kotlin?
a

altavir

11/09/2019, 5:33 AM
What is the problem with reading dataframes in Kotlin? There are libraries for all possible formats.
j

jimn

11/09/2019, 5:40 AM
@altavir maybe there is a faq for such things that i missed, im not seeing kotlin on https://github.com/topics/fixed-width or really anywhere else. having off-heap mmap on fwf is somehow a missed opportunity in pandas for random access sparse data. looks like same for kotlin.
a

altavir

11/09/2019, 5:41 AM
Pandas has multiple ways to serialize data. Which one are you talking about?
j

jimn

11/09/2019, 5:42 AM
serializtion is one thing. performing well is quite another with time series pivot and resequencing
these are things pandas commits excessive overhead to
a

altavir

11/09/2019, 5:43 AM
The question was about access, not performance.
If you are looking into in-memory formats, you should try Apache arrow. It looks really interesting.
j

jimn

11/09/2019, 5:45 AM
in pandas,. csv is optimized, but fwf is not. that's actually the less intuitive outcome, since fwf is basically free ISAM to memory map and csv requries extra state to accomodate variable lengths
i know apache arrow. i broke it on the first try in kotlin. there's a few tickets where i help them experience the jetty NIO bugs first-hand
yes arrow is very fast.
a

altavir

11/09/2019, 5:46 AM
Well, talking about performance of text-based formats seems strange to me. They are not made for performance.
j

jimn

11/09/2019, 5:47 AM
jdbc->arrow is also a neighbor of the jdbc->fwf code im writing now. the arrow team admits that when you work with 10's of thousands of columns it's not ideal or really commonly tested
a

altavir

11/09/2019, 5:47 AM
And still @bjonnh question was about reading, not performance.
j

jimn

11/09/2019, 5:47 AM
what is uncommon about text formats in data science?
@bjonnh this project started as couchdb conversion utilities but lately it's been a catch-all for pandas dataloading headaches as well, chiefly getting jdbc data.
@altavir if you can use the hardware to map a file for random access, and you choose not to, that's not on me.
Alex as a point of reference, with pandas, I need 350 gig swapfile to map 4 years of sales data across 70000 products using real world data. the source data is only a few gigs of csv, and even "a few gigs" is enough to rule out the success of loading most of the pandas data loading formats
fwf is an ISAM copmatible solution, and the order of magnitude is near to csv as far as on-disk layout. pandas should not be conflating the data by 100 times on pivot, but it doesz, maybe there's user error, but the pool of examples and aparticularly pandas examples at scale is nearly zero. datascience has a lot of tarpit example cases - 100k data file works well in tensorflow, where numpy overheads for even those could get into the gigabytes
@altavir also, i can sort fwf files using gnusort tools, etc. there is no better option, even relational is no match for unix on text files
b

bjonnh

11/11/2019, 6:14 PM
"What is the problem with reading dataframes in Kotlin? There are libraries for all possible formats." I didn't know that
a

altavir

11/11/2019, 6:16 PM
What format do you have in mind? Pickle?
b

bjonnh

11/11/2019, 6:16 PM
none in special, I was just interested in being able to exchange data between kotlin and pandas
👍 1
being able to get my df out and having python to plot for example
a

altavir

11/11/2019, 6:18 PM
You just take your favorite serialization format and find Java library to read it. By the way, beakerx has an autotranslate feature, that allows to load data in Java/Groovy/kotlin and pass open it in python in the same notebook
The favorite format for pandas serialization is csv/tsv. There are a lot of libraries for that in java. Also there python-like libraries like https://github.com/jtablesaw/tablesaw.
b

bjonnh

11/11/2019, 6:28 PM
I wanted to keep multi-levels, types etc
maybe I'll just use HDF
much faster to query than csv anyway
j

jimn

11/12/2019, 3:37 AM
hdf and avro and msgpack have been deprecated for arrow
jdk arrow libs are not entirely without some babysitting - the netty NIO libraries require some jvm switches to behave last i checked. 10's of thousands of columns is outside the goals of the format