Nguyen Hong Phuc phucnh

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Count empty values in csv file, grouped by column with pandas

Reference: Data Cleaning with Python and Pandas: Detecting Missing Values

Prerequisites

Python 3.6
pip

Running

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

CPU-bound
Blocking IO
Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

	import scala.collection._
	import com.twitter.util._

	scala> val buffer = mutable.ArrayBuffer.empty[Int]
	scala> println(Time.measure { (0 to 50000000).foreach { buffer += _ } }.inMillis)
	17610

	scala> var vector = immutable.Vector.empty[Int]
	scala> println(Time.measure { (0 to 50000000).foreach { vector :+= _ } }.inMillis)
	7865