title
10 One Liners to Impress Your Friends

Ruby • Perl • Python • PHP • Erlang • Java • JavaScript

The one liners are:

Multiple Each Item in a List by 2
Sum a List of Numbers
Verify if Exists in a String
Read in a File
Happy Birthday to You!
Filter list of numbers
Fetch and Parse an XML web service
Find minimum (or maximum) in a List
Parallel Processing
Sieve of Eratosthenes

One Liner #1 - Multiple Each Item in a List by 2

Ruby

p (1..10).map { |n| n * 2 }

# => [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]

Perl

my @list = map { $_ * 2 } 1..10;
say foreach @list;

Python

print map(lambda x: x * 2, range(1,11))

PHP

<? foreach(range(1, 10) as $i) echo $i * 2 . " ";

Erlang

[X * 2 || X <- lists:seq(1, 11)].

Java

int[] ia = range(1, 10).map(i -> i * 2).toArray();
// -or-
List<Integer> result = range(1, 10).map(i -> i * 2).boxed().collect(toList());

JavaScript

Array.from({ length: 10 }).map((_, i) => (i + 1) * 2);

One Liner #2 - Sum a List of Numbers

Ruby

p (1..1000).reduce { |sum, n| sum + n }
# -or-
p (1..1000).reduce(&:+)
# -or-
p  (1..1000).reduce(:+)
# -or-
p (1..1000).to_a.sum     # requires ruby 2.4+
# -or-
p (1..1000).sum          # requires ruby 2.5+
# => 500500

Perl

use List::Util qw(sum);
my $sum = sum 1..1000;
say $sum;

Python

print sum(range(1,1001))

PHP

<? echo array_sum(range(1, 1000));

Erlang

lists:sum(lists:seq(1, 1001)).

Java

range(1, 1000).sum();
// -or-
range(1, 1000).reduce(0, Integer::sum);
// -or-
Stream.iterate(0, i -> i + 1).limit(1000).reduce(0, Integer::sum);
// -or-
IntStream.iterate(0, i -> i + 1).limit(1000).reduce(0, Integer::sum);

JavaScript

??

One Liner #3 - Verify if Exists in a String

Ruby

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

Perl

my @wordList = ('groovy', 'akka', 'grails framework', 'spock', 'typesafe');
my $tweet = 'This is an example tweet talking about groovy and spock.';
my @verify = grep { rindex($tweet, $_) >= 0 } @wordList;
say @verify ? 'yes' : 'no';

Python

words = ["scala", "akka", "play framework", "sbt", "typesafe"]
tweet = "This is an example tweet talking about scala and sbt."
print any(word in tweet for word in words)

PHP

<?
$words = array("php", "foo", "framework", "apache", "nginx");
$tweet = "This is an example tweet talking about PHP and Apache.";

foreach($words as $word) if(stripos($tweet, $word) !== false) echo "$word\n";

Erlang

Words = ["scala", "akka", "play framework", "sbt", "typesafe"].
Tweet = "This is an example tweet talking about scala and sbt".
[lists:member(S, Words) || S <- string:tokens(Tweet, " ")].

Java

final List<String> keywords = Arrays.asList("brown", "fox", "dog", "pangram");
final String tweet = "The quick brown fox jumps over a lazy dog. #pangram";

keywords.stream().anyMatch(tweet::contains);
keywords.stream().reduce(false, (b, keyword) -> b || tweet.contains(keyword), (l, r) -> l || r);

JavaScript

??

One Liner #4 - Read in a File

Ruby

file_text = File.read("data.txt")
# -or-
file_lines = File.readlines("data.txt")

Perl

my $content = do { undef $/; open my $fh, "10_oneliners.pl"; <$fh> };
say $content;
# -or -
my @lines = do { open my $fh, "10_oneliners.pl"; <$fh> };
say @lines;

Python

print open("ten_one_liners.py").readlines()

PHP

<? echo file_get_contents("oneliners.php");

Erlang

file:read_file("ten_one_liners.erl").

Java

try (BufferedReader reader = new BufferedReader(new FileReader("data.txt"))) {
  String fileText = reader.lines().reduce("", String::concat);
}
// -or-
try (BufferedReader reader = new BufferedReader(new FileReader("data.txt"))) {
  List<String> fileLines = reader.lines().collect(toCollection(LinkedList<String>::new));
}
// -or-
try (Stream<String> lines = Files.lines(new File("data.txt").toPath(), Charset.defaultCharset())) {
  List<String> fileLines = lines.collect(toCollection(LinkedList<String>::new));
}

JavaScript

??

One Liner #5 - Happy Birthday to You!

Ruby

4.times { |n| puts "Happy Birthday #{n==2 ? "dear Tony" : "to You"}" }
# => Happy Birthday to You
# => Happy Birthday to You
# => Happy Birthday dear Tony
# => Happy Birthday to You

Perl

for my $i (1..4) { say 'Happy Birthday ', (($i == 3) ? 'dear Name' : 'to You') };

Python

print map(lambda x: "Happy Birthday to " + ("you" if x != 2 else "dear Name"),range(4))

PHP

<? foreach(range(1, 4) as $i) echo "Happy Birthday " .($i == 3 ? "dear Martin" : "to You") . "\n";

Erlang

["Happy Birthday " ++ case X of 2 -> "dear Robert"; _ -> "You" end || X <- lists:seq(1, 4)].

Java

range(1, 5).boxed().map(i -> { out.print("Happy Birthday "); if (i == 3) return "dear NAME"; else return "to You"; }).forEach(out::println);

JavaScript

??

One Liner #6 - Filter list of numbers

Ruby

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

Perl

my (@passed, @failed);
foreach my $n (49, 58, 76, 82, 88, 90) { my $aref = $n > 60 ? \@passed : \@failed; push @$aref, $n };
say join ",", @passed;
say join ",", @failed;

Python

print reduce(lambda(a,b),c: (a+[c],b) if c > 60 else (a,b + [c]), [49, 58, 76, 82, 88, 90],([],[]))

PHP

<? foreach(array(49, 58, 76, 82, 88, 90) as $i) $i > 60 ? ($passed[] = $i) : ($failed[] = $i);

Erlang

[X || X <- lists:seq(40, 60), X >= 50].

Java

Map<String, List<Integer>> result = Stream.of(49, 58, 76, 82, 88, 90).collect(groupingBy(forPredicate(i -> i > 60, "passed", "failed")));

JavaScript

??

One Liner #7 - Fetch and Parse an XML web service

Ruby

require 'open-uri'
require 'nokogiri'
results = Nokogiri::XML(open("http://search.twitter.com/search.atom?&amp;q=scala"))
# -or-
require "open-uri"
require "rexml/document"
results = REXML::Document.new(open("http://search.twitter.com/search.atom?&amp;q=scala"))

Perl

use HTTP::Tiny;
use XML::Simple;
use Data::Dumper;
print Dumper XMLin(HTTP::Tiny->new->get('http://search.twitter.com/search.atom?&q=perl')->{content});

Python

from xml.dom.minidom import parse, parseString
import urllib2
print parse(urllib2.urlopen("http://search.twitter.com/search.atom?&amp;q=python")).toprettyxml(encoding="utf-8")

PHP

<? echo simplexml_load_file("http://search.twitter.com/search.atom?q=php")->asXML();

Erlang

inets:start().
xmerl_scan:string(element(3, element(2, httpc:request("http://search.twitter.com/search.atom?&q=erlang")))).

Java

FeedType feed = JAXB.unmarshal(new URL("http://search.twitter.com/search.atom?&q=java8"), FeedType.class);
JAXB.marshal(feed, System.out);

JavaScript

??

One Liner #8 - Find minimum (or maximum) in a List

Ruby

p [14, 35, -7, 46, 98].min
# => -7
p [14, 35, -7, 46, 98].max
# => 98

Perl

my ($min, $max);
for my $n (14, 35, -7, 46, 98) { $min=$n if $n<$min };
for my $n (14, 35, -7, 46, 98) { $max=$n if $n>$max };
say $min;
say $max;
# -or-
use List::Util qw(min max);
my ($min, $max);
$min = min (14, 35, -7, 46, 98);
$max = max (14, 35, -7, 46, 98);
say $min;
say $max;

Python

print min([14, 35, -7, 46, 98])
print max([14, 35, -7, 46, 98])

PHP

<?
echo min(array(14, 35, -7, 46, 98)) . "\n";
echo max(array(14, 35, -7, 46, 98)) . "\n";

Erlang

lists:min(lists:seq(1, 10)).
lists:max(lists:seq(1, 10)).

Java

int min = Stream.of(14, 35, -7, 46, 98).reduce(Integer::min).get();
    min = Stream.of(14, 35, -7, 46, 98).min(Integer::compare).get();
    min = Stream.of(14, 35, -7, 46, 98).mapToInt(Integer::new).min();

int max = Stream.of(14, 35, -7, 46, 98).reduce(Integer::max).get();
    max = Stream.of(14, 35, -7, 46, 98).max(Integer::compare).get();
    max = Stream.of(14, 35, -7, 46, 98).mapToInt(Integer::new).max();

JavaScript

??

One Liner #9 - Parallel Processing

Ruby

require 'parallel'

Parallel.map(lots_of_data) do |chunk|
  heavy_computation(chunk)
end

Perl

use Parallel::Loops;
my @values;
my $pl = Parallel::Loops->new(4);
$pl->share(\@values);
$pl->foreach( [0..4], sub { push @values, exp($_) } );
say foreach @values;

Python

import multiprocessing
import math

print list(multiprocessing.Pool(processes=4).map(math.exp,range(1,11)))

PHP

<? ($pid = pcntl_fork()) == -1 ? exit(1) : ($pid ? hardCoreAction() && pcntl_wait($status) : hardCoreAction());

Erlang

[spawn(fun() -> io:format("~w~n", [X * 2]) end) || X <- lists:seq(1, 10)].

Java

long result = dataList.parallelStream().mapToInt(line -> processItem(line)).sum();

JavaScript

??

One Liner #10 - Sieve of Eratosthenes

In mathematics, the sieve of Eratosthenes is a simple, ancient algorithm for finding all prime numbers up to any given limit.

It does so by iteratively marking as composite (i.e., not prime) the multiples of each prime, starting with the first prime number, 2. The multiples of a given prime are generated as a sequence of numbers starting from that prime, with constant difference between them that is equal to that prime. This is the sieve's key distinction from using trial division to sequentially test each candidate number for divisibility by each prime.

The sieve of Eratosthenes can be expressed in pseudocode, as follows:
Input: an integer n > 1.

Let A be an array of boolean values, indexed by integers 2 to n,
initially all set to true.

for i = 2, 3, 4, ..., not exceeding √n:
  if A[i] i true:
    for j=i^2, i^2+i, i^2+2i, i^2+3i, ..., not exceeding n:
       A[j] := false.

Output: all i such that A[i] is true.
-- Wikipedia

Ruby

def primeSieve(n)
  primes = Array.new

  for i in 0..n-2
   primes[i] = i+2
  end

  index = 0
  while primes[index]**2 <= primes.last
    prime = primes[index]
    primes = primes.select { |x| x == prime || x % prime != 0 }
    index += 1
  end
  primes
end
primeSieve(11)
# => [2, 3, 5, 7, 11]

# -or-

def eratosthenes(n)
  # eratosthenes starts with nums = [nil, nil, 2, 3, 4, 5, ..., n],
  # then marks (　the nil setting　) multiples of 2, 3, 5, 7, ... there,
  # then returns all non-nil numbers which are the primes.

  nums = [nil, nil, *2..n]
  (2..Math.sqrt(n)).each do |i|
    (i**2..n).step(i){ |m| nums[m] = nil}  if nums[i]
  end
  nums.compact
end

# -or-

def primeSieve(n)
  nums = (2..n).to_a
  nums.each { |num| nums.map! { |i| i % num == 0 && i != num ? nil : i }.compact! }
end

# -or-

require 'prime'
Prime.take(5)
# => [2, 3, 5, 7, 11]

Perl

sub sieve {
  my $n = shift;
  my @composite;
  for my $i (2 .. int(sqrt($n))) {
    if (!$composite[$i]) {
      for (my $j = $i*$i; $j <= $n; $j += $i) {
        $composite[$j] = 1;
      }
    }
  }
  my @primes;
  for my $i (2 .. $n) {
    $composite[$i] || push @primes, $i;
  }
  @primes;
}

sub p { $_[0], @_ > 1 ? p(grep { $_ % $_[0] } @_) : () }
my @primes = p(2 .. 100);
say foreach @primes;

Python

# Using set lookup
def eratosthenes2(n):
    multiples = set()
    for i in range(2, n+1):
        if i not in multiples:
            yield i
            multiples.update(range(i*i, n+1, i))

print(list(eratosthenes2(100)))

# Using array lookup
def primes_upto(limit):
    is_prime = [False] * 2 + [True] * (limit - 1)
    for n in range(int(limit**0.5 + 1.5)): # stop at ``sqrt(limit)``
        if is_prime[n]:
            for i in range(n*n, limit+1, n):
                is_prime[i] = False
    return [i for i, prime in enumerate(is_prime) if prime]

print sorted(set(range(2,n+1)).difference(set((p * f) for p in range(2,int(n**0.5) + 2) for f in range(2,(n/p)+1))))

PHP

function iprimes_upto($limit)
{
  for ($i = 2; $i < $limit; $i++)
  {
	   $primes[$i] = true;
  }

  for ($n = 2; $n < $limit; $n++)
  {
	   if ($primes[$n])
	   {
	     for ($i = $n*$n; $i < $limit; $i += $n)
	     {
		      $primes[$i] = false;
	     }
	   }
  }
  return $primes;
}

<?
foreach($p = range(2, 100) as $v) foreach(range(2, $v - 1) as $c) if(!($v % $c) && $v != 2) unset($p[$v - 2]);

echo join("\n", $p);

Erlang

-module(sieveof).
-export([main/1,primes/1, primes/2]).                 

main(X) -> io:format("Primes: ~w~n", [ primes(X) ]).  

primes(X) -> sieve(range(2, X)).                                         
primes(X, Y) -> remove(primes(X), primes(Y)).                            

range(X, X) -> [X];                                                      
range(X, Y) -> [X | range(X + 1, Y)].                                    

sieve([X]) -> [X];                                                       
sieve([H | T]) -> [H | sieve(remove([H * X || X <-[H | T]], T))].        

remove(_, []) -> [];                                                     
remove([H | X], [H | Y]) -> remove(X, Y);                                
remove(X, [H | Y]) -> [H | remove(X, Y)].

N = 50.
[X || X <- lists:usort(lists:seq(2, N + 1)), not lists:member(X, lists:usort([(P * F) || P <- lists:seq(2, round(math:pow(N, 0.5)) + 2), F <- lists:seq(2, round(N / P))]))].

Java

import java.util.LinkedList;

public class Sieve{
       public static LinkedList<Integer> sieve(int n){
               if(n < 2) return new LinkedList<Integer>();
               LinkedList<Integer> primes = new LinkedList<Integer>();
               LinkedList<Integer> nums = new LinkedList<Integer>();

               for(int i = 2;i <= n;i++){ //unoptimized
                       nums.add(i);
               }

               while(nums.size() > 0){
                       int nextPrime = nums.remove();
                       for(int i = nextPrime * nextPrime;i <= n;i += nextPrime){
                               nums.removeFirstOccurrence(i);
                       }
                       primes.add(nextPrime);
               }
               return primes;
       }
}

JavaScript

function eratosthenes(limit) {
    var primes = [];
    if (limit >= 2) {
        var sqrtlmt = Math.sqrt(limit) - 2;
        var nums = new Array(); // start with an empty Array...
        for (var i = 2; i <= limit; i++) // and
            nums.push(i); // only initialize the Array once...
        for (var i = 0; i <= sqrtlmt; i++) {
            var p = nums[i]
            if (p)
                for (var j = p * p - 2; j < nums.length; j += p)
                    nums[j] = 0;
        }
        for (var i = 0; i < nums.length; i++) {
            var p = nums[i];
            if (p)
                primes.push(p);
        }
    }
    return primes;
}

Sieve of Eratosthenes References

Sieve of Eratosthenes @ Rosetta Code
Sieve of Eratosthenes @ Wikipedia

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classics-10-one-liners.md

classics-10-one-liners.md

One Liner #1 - Multiple Each Item in a List by 2

One Liner #2 - Sum a List of Numbers

One Liner #3 - Verify if Exists in a String

One Liner #4 - Read in a File

One Liner #5 - Happy Birthday to You!

One Liner #6 - Filter list of numbers

One Liner #7 - Fetch and Parse an XML web service

One Liner #8 - Find minimum (or maximum) in a List

One Liner #9 - Parallel Processing

One Liner #10 - Sieve of Eratosthenes

Sieve of Eratosthenes References

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One Liner #1 - Multiple Each Item in a List by 2

One Liner #2 - Sum a List of Numbers

One Liner #3 - Verify if Exists in a String

One Liner #4 - Read in a File

One Liner #5 - Happy Birthday to You!

One Liner #6 - Filter list of numbers

One Liner #7 - Fetch and Parse an XML web service

One Liner #8 - Find minimum (or maximum) in a List

One Liner #9 - Parallel Processing

One Liner #10 - Sieve of Eratosthenes

Sieve of Eratosthenes References