Could Someone please explain how to repeate my code recursivly?

Hi,

I am new to programming and following Chris P.s book. There is an
exercise in the book to write a method similar to .sort that will
arrange an array of string in alphabetical order. I will paste the
exercise:

OK. So we want to sort an array of words, and we know how to find out
which of two words comes first in the dictionary (using <).
What strikes me as probably the easiest way to do this is to keep two
more lists around: one will be our list of already-sorted words, and
the
other will be our list of still-unsorted words. Well take our list of
words,
find the smallest word (that is, the word that would come first in
the
dictionary), and stick it at the end of the already-sorted list. All
of the
other words go into the still-unsorted list. Then you do the same
thing
again but using the still-unsorted list instead of your original list:
find
the smallest word, move it to the sorted list, and move the rest to
the
unsorted list. Keep going until your still-unsorted list is empty.

I think I covered the first bit of the exercise but when I try to
repeat my method recursively it fails.
Would you be please so kind to take a look at my code and tell me what
am I doing wrong?

puts ‘Please enter a list of words you would like to arrange’
puts ‘in alphabetical order:’

list_of_words = []
input = ‘empty’

while input != ‘’
input = gets.chomp
if input != ‘’
list_of_words.push input
end
end

def arrange some_array
recursive_arrange some_array, []
end

def recursive_arrange unsorted_array, sorted_array

Initializing the array “still_unsorted_array”

    still_unsorted_array = []

Finding the smallest word on the array “list_of_words”

    smallest = unsorted_array [0]

    unsorted_array.each do |word|
            if smallest > word
                    smallest = word
            end
    end

Adding the smallest word from the array of “unsorted words” to the

array of “sorted_words”

    sorted_array.push smallest

Adding the words from the array of “unsorted_array” to the array of

“still_unsorted_array”

with the exception of the content of variable “smallest”

    bigger = 'empty'

    unsorted_array.each do |word|
            if word != smallest
                    bigger = word
                    still_unsorted_array.push bigger
            end
    end

Clearing the array of “unsorted_array” so it can be re-used

    unsorted_array = []

Adding the smallest word from the array of “still_unsorted words” to

the array of “sorted_words”

    smallest = still_unsorted_array [0]
    still_unsorted_array.each do |word|
            if smallest > word
                    smallest = word
            end
    end

Adding the smallest word from the array of “still_unsorted words” to

the array of “sorted_words”

    sorted_array.push smallest

Adding the remaining words from the array “still_unsorted_words” to

the array of

“unsorted_words”

    still_unsorted_array.each do |word|
            if word != smallest
                    bigger = word
                    unsorted_array.push bigger
            end
    end

This is the bit I tried to call the method recursively.

    if unsorted_array == unsorted_array = []
            puts sorted_array
            else
                    recursive_arrange unsorted_array, sorted_array
    end

puts ‘unsorted array:’
puts unsorted_array
puts ‘still unsorted array:’
puts still_unsorted_array
puts ‘sorted array:’
puts sorted_array

end

arrange list_of_words

On Jan 19, 2012, at 10:39 AM, Loren wrote:

Would you be please so kind to take a look at my code and tell me what
am I doing wrong?

You’re making this far, far, far more complicated than it needs to be.
Hint 1: you only need two arrays, sorted & unsorted, all the shuffling
in & out of temporary arrays is unnecessary and just complicates your
code–this is by far most important. Hint 2: use the appropriate
functions on enumerable (parent class of array) with blocks to get rid
of the loops–maybe your book hasn’t gotten to this yet, if so don’t
worry about it, but it’s those functions that let you express the
sorting part in about 10 lines or so of code.


Scott R.
[email protected]
http://www.elevated-dev.com/
(303) 722-0567 voice

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