O código deve receber um texto de entrada (não obrigatório, pode ser qualquer arquivo, stdin, string para JavaScript, etc):

This is a text and a number: 31.

A saída deve conter as palavras com seu número de ocorrência, classificadas pelo número de ocorrências em ordem decrescente:

a:2
and:1
is:1
number:1
This:1
text:1
31:1

Observe que 31 é uma palavra; portanto, uma palavra é qualquer coisa alfanumérica; o número não está atuando como separador; portanto, por exemplo, é 0xAFqualificado como uma palavra. Separadores serão qualquer coisa que não seja alfanumérica, incluindo .(ponto) e -(hífen), portanto, i.e.ou pick-me-upresultariam em 2, respectivamente, 3 palavras. Deve ser sensível a maiúsculas e minúsculas Thise thisincluir duas palavras diferentes, 'também seria um separador wouldne tserão 2 palavras diferentes dewouldn't .

Escreva o código mais curto no seu idioma de escolha.

Resposta correta mais curta até agora:

• grep e coreutils - 42 bytes

grep e coreutils  44  42

grep -io '[a-z0-9]*'|sort|uniq -c|sort -nr

Teste:

printf "This is a text and a number: 31." |
grep -io '[a-z0-9]*'|sort|uniq -c|sort -nr

Resulta em:

  2 a
  1 This
  1 text
  1 number
  1 is
  1 and
  1 31

Atualizar

• Use a opção que não diferencia maiúsculas de minúsculas e regex mais curto. Obrigado Tomas.

Java 8: 289

O que é muito bom, pois o java é uma linguagem muito não-golfe.

import java.util.stream.*;class C{static void main(String[]a){Stream.of(a).flatMap(s->of(s.split("[\\W_]+"))).collect(Collectors.groupingBy(x->x,Collectors.counting())).entrySet().stream().sorted(x,y->x.getValue()-y.getValue()).forEach(e->System.out.println(e.getKey()+":"+e.getValue()));}

Ungolfed:

import java.util.stream.*;
class C {
    static void main(String [] args){
        Stream.of(args).flatMap(arg->Stream.of(arg.split("[\\W_]+")))
            .collect(Collectors.groupingBy(word->word,Collectors.counting()))
            .entrySet().stream().sorted(x,y->x.getValue()-y.getValue())
            .forEach(entry->System.out.println(entry.getKey()+":"+entry.getValue()));
    }
}

Execute a partir da linha de comando:

java -jar wordCounter.jar This is a text and a number: 31.

APL (57)

⎕ML←3⋄G[⍒,1↓⍉G←⊃∪↓Z,⍪+⌿∘.≡⍨Z←I⊂⍨(I←⍞)∊⎕D,⎕A,⎕UCS 96+⍳26;]

por exemplo

      ⎕ML←3⋄G[⍒,1↓⍉G←⊃∪↓Z,⍪+⌿∘.≡⍨Z←I⊂⍨(I←⍞)∊⎕D,⎕A,⎕UCS 96+⍳26;]
This is a text and a number: 31.
 a       2
 This    1
 is      1
 text    1
 and     1
 number  1
 31      1

Explicação:

• ⎕D,⎕A,⎕UCS 96+⍳26: números, letras maiúsculas, letras minúsculas
• (I←⍞)∊: ler entrada, armazenar I, ver quais são alfanuméricos
• Z←I⊂⍨: dividir Iem grupos de caracteres alfanuméricos, armazenar emZ
• +⌿∘.≡⍨Z: para cada elemento Z, veja com que frequência ele ocorre
• Z,⍪: corresponde a cada elemento em Z pares com quantas vezes ocorre
• G←⊃∪↓: selecione apenas os pares únicos, armazene em G
• ⍒,1↓⍉G: obtenha índices classificados para as ocorrências
• G[... ;]: reordene as linhas de acordo Gcom os índices fornecidos

C #: 153c 144c 142c 111c 115c 118c 114c 113c

(via LINQPad no modo "C # Statements", sem incluir a string de entrada)

Versão 1: 142c

var s = "This is a text and a number: 31."; // <- line not included in count
s.Split(s.Where(c=>!Char.IsLetterOrDigit(c)).ToArray(),(StringSplitOptions)1).GroupBy(x=>x,(k,e)=>new{s,c=e.Count()}).OrderBy(x=>-x.c).Dump();

Ungolfed:

var s = "This is a text and a number: 31.";
s.Split(                                                     // split string on multiple separators
    s.Where(c => !Char.IsLetterOrDigit(c))                   // get list of non-alphanumeric characters in string
     .ToArray(),                                             // (would love to get rid of this but needed to match the correct Split signature)
    (StringSplitOptions)1                                    // integer equivalent of StringSplitOptions.RemoveEmptyEntries
).GroupBy(x => x, (k, e) => new{ s = k, c = e.Count() })     // count by word
 .OrderBy(x => -x.c)                                         // order ascending by negative count (i.e. OrderByDescending)
 .Dump();                                                    // output to LINQPad results panel

Resultados:

Versão 2: 114c

( [\w]inclui _, o que está incorreto ! ; [A-z]inclui [ \ ] ^ _ `; resolver [^_\W]+)

var s = "This is a text and a number: 31."; // <- line not included in count
Regex.Matches(s, @"[^_\W]+").Cast<Match>().GroupBy(m=>m.Value,(m,e)=>new{m,c=e.Count()}).OrderBy(g=>-g.c).Dump();

Ungolfed:

Regex.Matches(s, @"[^_\W]+")                                   // get all matches for one-or-more alphanumeric characters
     .Cast<Match>()                                            // why weren't .NET 1 collections retrofitted with IEnumerable<T>??
     .GroupBy(m => m.Value, (m,e) => new{ m, c = e.Count() })  // count by word
     .OrderBy(g => -g.c)                                       // order ascending by negative count (i.e. OrderByDescending)
     .Dump();                                                  // output to LINQPad results panel

Resultados: (como versão 1)

R, 58 caracteres

sort(table(unlist(strsplit(scan(,""),"[[:punct:]]"))),d=T)

Uso:

sort(table(unlist(strsplit(scan(,""),"[[:punct:]]"))),d=T)
1: This is a text and a number: 31.
9: 
Read 8 items

     a     31    and     is number   text   This 
     2      1      1      1      1      1      1 

perl6: 49 caracteres

.say for get.comb(/\w+/).Bag.pairs.sort(-*.value)

Penteie a entrada para correspondência de itens \w+, coloque a lista resultante de palavras em umBag , peça seus pares e classifique-os por valor negativo. (A estrela *é o que quer que seja , não é multiplicação aqui)

saída:

"a" => 2
"This" => 1
"is" => 1
"text" => 1
"and" => 1
"number" => 1
"31" => 1

Python 101 97

import re
a=re.split('[_\W]+',input())
f=a.count
for w in sorted(set(a),key=f)[::-1]:print w,f(w)

Agora funciona com nova linha:

$ python countword.py <<< '"This is    a text and a number: 31, and a\nnewline"'
a 3
and 2
31 1
number 1
newline 1
is 1
text 1
This 1

PHP - 84 bytes

<?$a=array_count_values(preg_split('/[_\W]+/',$argv[1],0,1));arsort($a);print_r($a);

A entrada é aceita como argumento de linha de comando, por exemplo:

$ php count-words.php "This is a text and a number: 31."

Saída para a sequência de amostras:

Array
(
    [a] => 2
    [number] => 1
    [31] => 1
    [and] => 1
    [text] => 1
    [is] => 1
    [This] => 1
)

PowerShell (40)

$s -split"\W+"|group -ca|sort count -des

$ s é uma variável que contém a sequência de entrada.

Perl 69

$h{$_}++for<>=~/\w+/g;print"$_: $h{$_}
"for sort{$h{$b}-$h{$a}}keys%h

Recomendações adicionadas de @primo e @protist

Powershell: 57 55 53 62 57

(não incluindo a sequência de entrada)

$s = "This is a text and a number: 31."    # <-- not counting this line...
[Regex]::Matches($s,"[^_\W]+")|group -ca|sort{-$_.Count}

retorna:

Count Name                      Group
----- ----                      -----
    2 a                         {a, a}
    1 and                       {and}
    1 31                        {31}
    1 number                    {number}
    1 This                      {This}
    1 is                        {is}
    1 text                      {text}

(com adereços para @microbian para o grupo -ca)

EcmaScript 6

Versão 1 (108 caracteres)

s.split(_=/[^a-z\d]/i).map(x=>_[x]=-~_[x]);keys(_).sort((a,b)=>_[a]<_[b]).map(x=>x&&console.log(x+':'+_[x]))

Versão 2 (102 caracteres)

s.split(_=/[^a-z\d]/i).map(x=>_[x]=-~_[x]);keys(_).sort((a,b)=>_[a]<_[b]).map(x=>x&&alert(x+':'+_[x]))

Versão 3 (105 caracteres)

s.match(_=/\w+/g).map(x=>_[x]=-~_[x]);alert(keys(_).sort((a,b)=>_[a]<_[b]).map(x=>x+':'+_[x]).join('\n'))

Versão 4 (94 caracteres)

s.match(_=/\w+/g).map(x=>_[x]=-~_[x]);keys(_).sort((a,b)=>_[a]<_[b]).map(x=>alert(x+':'+_[x]))

Versão 5 (sem alerta; 87 caracteres)

s.match(_=/\w+/g).map(x=>_[x]=-~_[x]);keys(_).sort((a,b)=>_[a]<_[b]).map(x=>x+':'+_[x])

Versão 6 (100 caracteres)

keys(_,s.match(_=/\w+/g).map(x=>_[x]=-~_[x])).sort((a,b)=>_[a]<_[b]).map(x=>console.log(x+':'+_[x]))

Saída:

a:2
31:1
This:1
is:1
text:1
and:1
number:1

Groovy 77 82

regex alterado de [^\w]+para [^\d\p{L}]+para resolver o problema com sublinhado

String s = 'This is a text and a number: 31'

def a=s.split(/[^\d\p{L}]+/) 
a.collectEntries{[it, a.count(it)]}.sort{-it.value}

sem primeira linha, 82 caracteres

saída:

[a:2, This:1, is:1, text:1, and:1, number:1, 31:1]

GNU awk + coreutils: 71 69

gawk 'BEGIN{RS="\\W+"}{c[$0]++}END{for(w in c)print c[w],w}'|sort -nr

Embora gawk asorttrabalhe em matrizes associativas, aparentemente não preserva os valores do índice, necessitando dasort

printf "This is a text and a number: 31." | 
gawk 'BEGIN{RS="\\W+"}{c[$0]++}END{for(w in c)print c[w],w}'|sort -nr
2 a
1 This
1 text
1 number
1 is
1 and
1 31

GNU awk 4.x: 100 93

Uma solução gawk um pouco maior, porém pura, usada PROCINFOpara definir a ordem de classificação padrão para o array associativo (parece exigir um gawk relativamente recente -> 4.x?)

BEGIN{RS="\\W+";PROCINFO["sorted_in"]="@val_num_desc"}
{c[$0]++}
END{for(w in c)print c[w],w}

Javascript - 132 126 caracteres!

(Código JS mais curto)

o={},a=[]
for(i in s=s.split(/[\W_]+/))o[z=s[i]]=o[z]+1||1
for(j in o)a.push([j,o[j]])
a.sort(function(b,c){return c[1]-b[1]})

Melhorou a regex e algumas edições.

Ungolfed

s = s.split(/[\W_]+/), o={}, a=[]; // split along non-char letters, declare object and array

for (i in s) { n = s[i]; o[n] = o[n] + 1 || 1 } // go through each char and store it's occurence

for (j in o) a.push( [j, o[j]] ); // store in array for sorting

a.sort(function (b, c){ return c[1] - b[1]; }); // sort !

<= // make s = "Quão brilhante é este dia, não é, é"

=> [['é', 3],
['Como', 1],
['brilhante', 1],
['this', 1],
['day', 1],
['isn', 1] ,
['t', 1]]

Antigo - 156 143 141 140 132 caracteres

s=s.split(/[^\w]+/g),o={}
for(i in s){n=s[i];o[n]=o[n]+1||1}a=[]
for(j in o)a.push([j,o[j]])
a.sort(function(b,c){return c[1]-b[1]})

Deu uma primeira tentativa no golfe. Feedback apreciado.

EcmaScript 6, 115 100 87 (sem prompt e alerta)

Thanks to @eithedog:

s.match(/\w+/g,a={}).map(w=>a[w]=-~a[w]),keys(a).map(w=>[w,a[w]]).sort((a,b)=>b[1]-a[1])

With prompt and alert (100):

prompt(a={}).match(/\w+/g).map(w=>a[w]=-~a[w]);alert(keys(a).map(w=>[w,a[w]]).sort((a,b)=>b[1]-a[1]))

Run it in Firefox.

Ruby 58 82 65

h=Hash.new 0
gets.scan(/[\d\w]+/){h[$&]+=1}
p *h.sort_by{|k,v|-v}

Test run:

$ ruby counttext.rb <<< "This is a text and a number: 31."
["a", 2]
["text", 1]
["This", 1]
["is", 1]
["and", 1]
["number", 1]
["31", 1]

^{Edit 58->80: Ok, I was way off. I forgot to sort the words by occurrences. Also, Array#uniq is not an enumerator, but uses a given block to compare elements, so passing puts to it didn't filter out duplicates (not that it says that we should).}

F# - 169

let f s=(s+"").Split(set s-set(['a'..'z']@['A'..'Z']@['0'..'9'])|>Set.toArray)|>Seq.where((<>)"")|>Seq.countBy id|>Seq.sortBy((~-)<<snd)|>Seq.iter((<||)(printfn"%s:%d"))

Degolfed:

let count (s : string) =
    s.Split (set s - set (['a'..'z']@['A'..'Z']@['0'..'9']) |> Set.toArray)
 |> Seq.where ((<>) "")
 |> Seq.countBy id
 |> Seq.sortBy ((~-) << snd)
 |> Seq.iter ((<||) (printfn "%s:%d"))

Output when called from fsi:

> "This is a text and a number: 31." |> f
a:2
This:1
is:1
text:1
and:1
number:1
31:1
val it : unit = ()

Update: Some explanation as requested in the comments.

Uses set functions to generate an array of non alphanumeric characters in the input to pass to String.Split, then uses sequence functions to filter out empty strings, generate word counts and print the result.

Some golfing tricks: Adds an empty string to the function argument s to force type inference of the argument as a string rather than explicitly declaring the type. Uses Seq.where rather than Seq.filter to save a few characters (they are synonyms). Mixes forward pipe and ordinary function application in an attempt to minimize characters. Uses currying and (op) syntax to treat <> ~- and <|| operators as regular functions to avoid declaring lambdas to filter empty strings, sort by descending count and print tuples.

Python - 95 ( now 87 thanks to @primo)

d=__import__('re').findall(r'\w+',raw_input())
print sorted(map(lambda y:(y,d.count(y)),d))

Sample input :

'This is a text and a number: 31'

Sample output :

[('This', 1),('is', 1), ('a', 2),('text', 1),('and', 1),('a', 2),('number', 1),('31', 1)]

Any improvement sugestion would be appreciated

JavaScript 160 144 (Edited: to meet requirements)

f=Function;o={};s.replace(/\w+/g,f('a','o[a]=++o[a]||1'));Object.keys(o).sort(f('b,c','return o[c]-o[b]')).map(f('k','console.log(k+" "+o[k])'))

Unminified:

f=Function;
o = {};
s.replace(/\w+/g, f('a','o[a]=++o[a]||1'));
Object.keys(o).sort(f('b,c', 'return o[c]-o[b]')).map(f('k','console.log(k+" "+o[k])'))

Logs each word to console in order, passing the following string:

s="This is sam}}ple text 31to test the effectiveness of this code, you can clearly see that this is working-as-intended, but you didn't doubt it did you?.";

Outputs:

you 3
this 2
is 2
can 1
text 1
31to 1
test 1
the 1
effectiveness 1
of 1
This 1
code 1
sam 1
ple 1
clearly 1
see 1
that 1
working 1
as 1
intended 1
but 1
didn 1
t 1
doubt 1
it 1
did 1 

I don't have the heart to use alert().

k [71 chars]

f:{s:" ",x;`_k!m@k:|(!m)@<.:m:#:'=`$1_'(&~((),/:s)like"[a-zA-Z0-9]")_s}

Any other character except alphanumeric chars will be considered as delimiter.

example

f "This is a text and a number: 31."
a     | 2
31    | 1
number| 1
and   | 1
text  | 1
is    | 1
This  | 1

example

f "won't won won-won"
won| 4
t  | 1

Javascript (135)

u=/\w+/g
for(i=s.length;i--;)for(w in a=s.match(u))u[w=a[w]]=u[w]||a.reduce(function(p,c){return p+=w==c},0)==i&&!console.log(w+":"+i)

Unminified:

u=/\w+/g;for (i=s.length;i--;)
    for(w in a=s.match(u))
        u[w=a[w]] = u[w] || 
           a.reduce(function(p,c){return p+=w==c},0)==i && !console.log(w+":"+i)

Loops over every possible number of matches in descending order, and outputs words with that number of occurrences. Just to be horrible.

Notes: Alert would have reduced the length some. Strictly speaking alphanumeric should be [^\W_]

Haskell (153 = 104 code + 49 import)

Pretty straight-forward, totally composed function... no argument even necessary! This is my first golf, so go easy, maybe? :)

import Data.Char
import Data.List
import Data.Ord
so=reverse.(sortBy$comparing snd).(map(\t@(x:_)->(x,length t))).group.sort.(map$filter isAlphaNum).words

Output:

*Main> so "This is a text and a number: 31."
[("a",2),("text",1),("number",1),("is",1),("and",1),("This",1),("31",1)]

q (50)

desc count each group" "vs ssr[;"[^0-9A-Za-z]";" "]

• ssr replaces non alphanumeric
• " "vs splits the result into a symbol list
• count each group counts creates a dict matching distinct elements of the list with the number of occurances
• desc sorts the dict by descending values

edit: fixed accidentally matching ascii 58-64 and 91-96

Pure Bash (no external programs), 164

This is longer than I'd hoped, but I wanted to see if the necessary counting and sorting (in the right direction) could be done purely with bash arrays (associative and non-associative):

declare -A c
for w in ${@//[[:punct:]]/ };{ ((c[$w]++));}
for w in ${!c[@]};{ i=${c[$w]};((m=i>m?i:m));s[$i]+=$w:;}
for((i=m;i>0;i--));{ printf "${s[i]//:/:$i
}";}

Save as a script file, chmod +x, and run:

$ ./countoccur This is a text and a number: 31.
a:2
and:1
number:1
text:1
31:1
is:1
This:1
$ 

AWK

awk -vRS='[^A-Za-z0-9]' '$0{c[$0]++}END{for(i in c)print c[i]"\t"i": "c[i]|"sort -nr|cut -f2-"}'

Does the job without gawkish extensions:

$ echo 'This is a text and a number: 31.' | awk -vRS='[^A-Za-z0-9]' '$0{c[$0]++}END{for(i in c)print c[i]"\t"i": "c[i]|"sort -nr|cut -f2-"}'
a: 2
This: 1
text: 1
number: 1
is: 1
and: 1
31: 1

If printing "count: word" instead, it would be a bit shorter but I wanted to mimic the given example output...

Tcl, 99 bytes

proc C s {lmap w [split [regsub -all \[^\\w|\ \] $s {}]] {dict inc D $w}
lsort -s 2 -inde 1 -de $D}

Try it online!

Python 2.X (108 - Characters)

print'\n'.join('{}:{}'.format(a,b)for a,b in __import__("collections").Counter(raw_input().split()).items())

Python 3.X (106 - Characters)

print('\n'.join('{}:{}'.format(a,b)for a,b in __import__("collections").Counter(input().split()).items())

Haskell - 137

import Data.List
count text=let textS=(words(text\\".-\':")) in (sortBy (\(_,n) (_,m) -> compare m n)).nub$map(\t->(t,(length.(filter(==t)))textS)) textS

Python 3 - 76

The requirement of splitting on non-alphanumeric chars unfortunately extends the code by 19 chars. The output of the following is shown correctly. If you are not sure, add a .most_common() after the .Counter(...).

i=__import__
print(i('collections').Counter(i('re').findall('\w+',input())))

In/Output

Given the input of This is a text and a number: 31. you get following output:

Counter({'a': 2, 'is': 1, 'This': 1, 'and': 1, '31': 1, 'number': 1, 'text': 1})

I tried it with other values like

1 2 3 4 5 6 7 8 2 1 5 3 4 6 8 1 3 2 4 6 1 2 8 4 3 1 3 2 5 6 5 4  2 2 4 2 1 3 6

to ensure, the output-order does not rely on the key's value/hash. This example produces:

Counter({'2': 8, '3': 6, '1': 6, '4': 6, '6': 5, '5': 4, '8': 3, '7': 1})

But as I said, print(i('collections').Counter(i('re').findall('\w+',input())).most_common()) would return the results as an definitly ordered list of tuples.

Python 3 - 57 (if a space would be enough for splitting :P)

print(__import__('collections').Counter(input().split()))