RosettaStone.md

Rosetta Stone

This consists of a "Rosetta Stone" of code syntax between R, Python, and Julia. The aim is to help those who are proficient in one language easily translate their code/understanding to another.

Basic actions (REPL, package ecosystem, etc.)

Action	R code	Python code	Julia code
execute script from REPL	source('script.R')	execfile('script.py')	include("script.jl")
install a package	install.packages("pkg")	[from OS terminal]: pip install pkg	Pkg.add("pkg")
load a package	library(pkg) or require(pkg)	import pkg	using pkg
execute shell command	system('command')	call(["command"]) [req. subprocess package]	run(`command`)
what kind of object is x?	class(x)	type(x)	typeof(x)

Working with arrays

Action	R code	Python code	Julia code
array indexing	x[]	x[]	x[]
first index	1	0	1
last element of x	x[length(x)]	x[-1]	x[end]

Working with data frames

Action	R code	Python code	Julia code
data frame package?	native	pandas	DataFrames
convert array to data frame?	df <- as.data.frame(array)		df = DataFrame(array)
read CSV to data frame?	read.csv('file.csv')		readtable("file.csv")
convert JSON to data frame?	library(jsonlite); df <- fromJSON('file.json')