Shulou(Shulou.com)06/02 Report--

This article mainly introduces "what single-line code does Ruby have". In daily operation, I believe many people have doubts about what single-line code Ruby has. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the questions of "what single-line code does Ruby have?" Next, please follow the editor to study!

1. Each element in the array is multiplied by 2

(1. 10). Map {| n | n * 2}

two。 Summation of elements in an array

(1.. 1000). Inject {| sum, n | sum + n}

Or use the (built-in) Symbol#to_proc syntax, which is available since Ruby 1.8.7:

(1... 1000). Inject (&: +)

Even pass a symbol directly:

(1.. 1000). Inject (: +)

3. Verify that tokens exists in the string

Words = ["scala", "akka", "play framework", "sbt", "typesafe"] tweet = "This is an example tweet talking about scala and sbt." Words.any? {| word | tweet.include? (word)}

4. Read a file

File_text = File.read ("data.txt") file_lines = File.readlines ("data.txt")

The latter includes "\ n" at the end of each element of the array, which can be trimmed by appending .map {| str | str.chop} or using an alternative version:

File.read ("data.txt") .split (/\ n /)

5. Happy birthday

4.times {| n | puts "Happy Birthday # {dear Tony": "to You"}

6. Filter numbers in an array

[49, 58, 76, 82, 88, 90] .partition {| n | n > 60}

7. Get and parse a XML Web service

Require 'open-uri' require' hpricot' results = Hpricot (open ("http://search.twitter.com/search.atom?&q=scala"))

This example requires open-uri or hpricot or equivalent libraries (you can use the built-in if you prefer). There's not much code, but Scala wins out here.

8. Find the minimum (or *) value in the array

[14, 35,-7, 46, 98] .min [14, 35,-7, 46, 98] .max

9. Parallel processing

Require 'parallel' Parallel.map (lots_of_data) do | chunk | heavy_computation (chunk) end

Unlike Scala, multicore support is not built-in. It needs parallel or something like that.

10. Ella Tostney sieving method

Scala's single line of code is smart, but completely unreadable. Although it is not a single line of code here, a simpler implementation can be written with Ruby:

Index = 0 while primes [index] * * 2

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