avg_word_len.rid

@#
This example shows how to use standard library functional methods
such as map and filter.
Str methods are also used.
* Prerequisites :
collections examples 'Str' and 'Functional' sections
* Statement :
Given a string containing ASCII characters, find the average word length.
A compound word (multiple words separated by a '-') must be handled :
well-defined has a length of 4 + 1 + 7 = 12 (not 4, 7)
@#

# Given text (from https://en.wikipedia.org/wiki/Algorithm)
text = @'
In mathematics and computer science, an algorithm is a finite sequence of
well-defined, computer-implementable instructions, typically to solve a class
of specific problems or to perform a computation.
@'

# 1. Create the allow list containing every character a word can have
lower_letters = ''.join(map(
    # Lower case ascii codes
    Str.ord('a') ->= Str.ord('z'),
    # Convert to char (default method)
    Str.chr))

upper_letters = ''.join(map(
    # Upper case ascii codes
    Str.ord('A') ->= Str.ord('Z'),
    # Convert to char (lambda method)
    |ascii| Str.chr(ascii)))

allowed_chars = lower_letters + upper_letters + '-'
allowed_char_codes = allowed_chars.map(|c| Str.ord(c))
not_allowed_chars = ''.join(map(
    # All char codes not in allowed_char_codes
    filter(1 -> 128, |code| code not in allowed_char_codes),
    # Stringify
    Str.chr))

print 'Allowed chars :', allowed_chars

# 2. Split text into words
words = text.split(not_allowed_chars)

print 'Words :', words

# 3. Compute the average word length
avg_len = sum(map(words, len)) / len(words)

print 'Average word length :', avg_len