How do I Fix this Python Variable Issue?

Question

Alright, if you run the below code in Python it only prints the first letter of the question variable, however it prints the rest just fine. This only happens \when I have the for loop function inside of my Python script. Any ideas on how to fix it so I get the entire question variable printing?

    import random
    global nouns
    global verbs
    global question
    nouns =["website","browser","server","printer","computer","disc","software","desktop","a internet connection","the internet","site","forum","smf forum","phpbb forum","money making website","money making blog","firefox","chrome","opera","",""]
    verbs = ["cosntruct","build","create","design","update","reconstruct","clean","fix","repair","browse","discover","formualte","form","plan"]
    question = ["How do I","How would I", "how do i", "how would i", "what is a", "what is the", "how would i", "how should i", "when does a", "When does a", "How should I"]


    def q_gen():
       global nouns
       global verbs
       global question
       noun_pick = random.choice(nouns)
       verb_pick = random.choice(verbs)
       question = random.choice(question)
       create = question+" "+verb_pick+" "+noun_pick+"?"
       print create

    num_count = 0
    for num_count in range(1, 100):
       num_count=num_count+1
       q_gen()

I was interested and ran the script. Some of these are gold. "how should i clean the internet?" Indeed, how should I clean the internet? — Corey
– Corey, Commented Dec 9, 2010 at 2:54

Wesley · Accepted Answer · 2010-12-09 03:09:07Z

9

This is happening because you are overwriting the global variable question with one of the values of question at this line:

question = random.choice(question)

This means that the following occurs:

question = [...] # question is a list of strings
question = random.choice(question) # question is a single string
question = random.choice(question) # question is a character from that string

The solution is to replace the variable name with something else:

question_pick = random.choice(question)
create = question_pick+" "+verb_pick+" "+noun_pick+"?"

A few notes on style

There are a number of improvements you can make to your code. These changes could improve readability, improve performance, and otherwise make your code more idiomatic.

Declaring variables. This is not done in Python. When you assign to a variable, it springs into existence. This includes for statements
```
global a # Unnecessary and dangerous
a = 0
```

Iteration. When you say for x in ..., you're executing a suite of statements again and again. Each time you go through the suite, x is assigned to the next item. You do not need to assign or increment x yourself.

x = 0 # Not necessary; x is about to be assigned to the first
      # element of range(10), which is 0
for x in range(10):
    ...
    x = x + 1 # Not necessary; as soon as this statement is done,
              # x will be assigned to the next element of range(10)

Globals.
- You don't need them. When you use name = ..., you are creating a module-level variable. Each variable is accessible everywhere in your module (that is, in your current .py file)
- They're dangerous. If some other module is using a variable named name, you could be in for a nasty surprise. Keep this in mind if you plan to develop this code further.
String formatting. The idea is that you create a template, then put tags where you want values dropped in. The %s tag means "Interpret the next variable as a string and put it here".
```
create = "%s %s %s?" % (question, verb_pick, noun_pick)
```
Style. Python has a style guide known as PEP 8. Making sure your code adheres to PEP 8 keeps it readable and makes it look more similar to other Python code. For example, operators should be surrounded by a single space, there should be a single space after a comma, etc.

edited Dec 9, 2010 at 3:09

answered Dec 9, 2010 at 2:40

Wesley

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2 Comments

eldarerathis Over a year ago

Don't forget to change question to question_pick on the last line :)

Wesley Over a year ago

Ah, crumbs. Thanks eldarerathis and carl. And I even specifically copied that line out so I'd have a chance to change it.

idbrii · Accepted Answer · 2010-12-09 02:41:15Z

This line modifies your global variable:

 question = random.choice(question)

And after the first time, random.choice is given a string instead of a list, so it randomly picks a letter. From then on, random.choice is given a single character string, so it always uses the same letter.

This error occurred because you unnecessarily used global. Writing it without global would give a compile error because question was modified.

Here's the code without global:

import random
nouns =["website","browser","server"]
verbs = ["construct","build","create"]
question = ["How do I","How would I", "how do i"]

def q_gen():
    noun_pick = random.choice(nouns)
    verb_pick = random.choice(verbs)
    question_pick = random.choice(question)
    create = question_pick+" "+verb_pick+" "+noun_pick+"?"
    print create

for num_count in range(1, 100):
    q_gen()

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