[SOLVED] Word frequency elegantly in Powershell

Word frequency elegantly in Powershell

Donald Knuth once got the task to write a literate program computing the word frequency of a file.

Read a file of text, determine the n most frequently used words, and print out a sorted list of those words along with their frequencies.

Doug McIlroy famously rewrote the 10 pages of Pascal in a few lines of sh:

tr -cs A-Za-z '\n' |
tr A-Z a-z |
sort |
uniq -c |
sort -rn |
sed ${1}q

As a little exercise, I converted this to Powershell:

(-split ((Get-Content -Raw test.txt).ToLower() -replace '[^a-zA-Z]',' ')) |
  Group-Object |
  Sort-Object -Property count -Descending |
  Select-Object -First $Args[0] |
  Format-Table count, name

I like that Powershell combines sort | uniq -c into a single Group-Object.

The first line looks ugly, so I wonder if it can be written more elegantly? Maybe there is a way to load the file with a regex delimiter somehow?

One obvious way to shorten the code would be to uses the aliases, but that does not help readability.

Solution

Thanks js2010 and LotPings for important hints. To document what is probably the best solution:

$Input -split '\W+' |
  Group-Object -NoElement |
  Sort-Object count -Descending |
  Select-Object -First $Args[0]

Things I learned:

$Input contains stdin. This is closer to McIlroys code than Get-Content some file.
split can actually take regex delimiters
the -NoElement parameter let me get rid of the Format-Table line.