Misunderstanding logic

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January 1st, 2013, 04:54 AM

jomiscli

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Join Date: Dec 2012

Posts: 26

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Misunderstanding logic

Hey in the python book I am learning out of one of the challenges asks me to print a list of words in random order without repeating any. I accomplished it but I do not understand why my while and if statement operators work. I am still extremely new to programming and Python so if it's a stupid question, I'm sorry! Here is the code:

Code:

import random

words = ["Wordone",
         "Wordtwo",
         "Wordthree",
         "Wordfour",
         "Wordfive",
         "Wordsix",
         "Wordseven",
         "Wordeight",
         "Wordnine",
         "Wordten",]

words_2 = []

words_length = len(words)

while words_length != -1:
    random_word = random.choice(words)
    words_length -= 1

    if words_length != 9:
        words_2.append(random_word)
        words.remove(random_word)

for i in words_2:
    print(i)

Thanks! Happy New Year!

January 1st, 2013, 08:20 AM

b49P23TIvg

Contributing User

Join Date: Aug 2011

Posts: 3,347

Time spent in forums: 1 Month 2 Weeks 3 Days 6 h 53 m 17 sec
Reputation Power: 383

Program works because, having miscounted by 1 in the loop you inserted extra code to let the loop run an extra time. Please run your program with the "instructive print statement". 9 isn't a completely special number. You could use 2 or 7 also.

Code:

import random

words = ["Wordone",
         "Wordtwo",
         "Wordthree",
         "Wordfour",
         "Wordfive",
         "Wordsix",
         "Wordseven",
         "Wordeight",
         "Wordnine",
         "Wordten",]

words_2 = []

words_length = len(words)

while words_length != -1:
    # instructive print statement follows #############################
    print('%d %s'%(words_length,str(words)))
    random_word = random.choice(words)
    words_length -= 1

    if words_length != 9:
        words_2.append(random_word)
        words.remove(random_word)

for i in words_2:
    print(i)

Let's fix the program, because yours won't work when words has 7 items.

Code:

import random
import string

words = list(string.digits)

words_2 = []

while words:            # in other words, stop when the list is empty.
    random_word = random.choice(words)
    words_2.append(random_word)
    words.remove(random_word)

print('\n'.join(words_2))



################# another way:



words = 'a b c wordsSEVEN'.split()
words_2 = words[:]                        # copy the words
random.shuffle(words_2)                   # shuffle them
print('\n'.join(words_2))                 # display the words

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January 2nd, 2013, 01:41 AM

jomiscli

Registered User

Join Date: Dec 2012

Posts: 26

Time spent in forums: 10 h 38 m 35 sec
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Thank you!

January 2nd, 2013, 06:42 PM

jomiscli

Registered User

Join Date: Dec 2012

Posts: 26

Time spent in forums: 10 h 38 m 35 sec
Reputation Power: 0

Thanks for the information. I really like the:

Code:

.spilt()
.join()
random.shuffle()

I just started python like 2 weeks ago, my first programming language. I am VERY limited on the different tools I can use for certain things. My code is based off just what I learned in the first 5 chapters of the book I am reading from, lol.

I think another issue I am having is creating and understanding certain algorithms. I know this is essential and I am pretty good at math but not beyond like algebra, not because I am stupid but because I've never taken the classes. Any advice on how to learn this a little better too outside of actually taking a more advanced math class?

Thank you again! I will get much use out of the info you shared with me

Misunderstanding logic

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