Python 3.X 麻烦，必须遍历一个列表，在另一个列表中调用函数，对齐宽度

Question

With this python assignment, I am trying to get the end result of producing a star for a movie rating. I am having difficulties because even with one to one help, I cannot decipher how to return the list seen below in the instructions.

instructions

"Write a function called count_ratings that will take a list of asterisks that represent an individuals rating for a given app and return a list of the number of 5 stars, 4 stars, 3 stars, 2 stars, and 1 star ratings. For example, if you called this function and passed it the list [" ", " *", "****", "* ","*****", "****", "**"] it would return the list [1, 1, 2, 2, 1] (where this means there are (1) 1-star rating, (1) 2-star rating, (2) 3-star rating, (2) 4-star ratings and (1) 5-star rating.)"*

At which I did that correctly, or at least I thought But as I went on to the further instructions.

1. Write a function called print_ratings that takes no parameters. This function will:

◦ Use the code at the end of the section to create a ratings variable that represents the list of ratings that you are going to use to in this program.

ratings = ["*****", " ", " ", " ", " ", "***", "*****", "****", "****","*",

" ", " ", "* ", "***", "*****", "*****", "*****", "*****", "*****"]

• Call the count_ratings function passing it the list of ratings. • Take the list that count_ratings returns and iterate through it and print out the rating

breakdown based on what the count_ratings function returns. Suppose count_ratings returns the following list [4, 2, 4, 2, 6], you want to print a histogram of this count. See the example output below.

1. Call print_ratings from main .
2. Run your code to verify that it works correctly.

At which I had done correctly, but.. as I tried calling the variable the error was stated as 'name 'count_list' is not defined' This is the end result of the output

5 Stars: |# # # # # # # |

4 Stars: |# # |

3 Stars: |# # # # |

2 Stars: |# # |

1 Stars: |# # # # |

The list must be printed in descending order, labeled as shown above.

• Each ' # ' represents one rating of X number of stars. So in the example provided,there are six entries with 5 stars, two entries with 4-stars and etc.

• Each visual representation of the count must be left justified, with a total width of 25. Place the pipe symbol to the left and right of the printed line

Here is where I got to, any help is needed, because I cannot find the solution after switching out variables and parameters I also need help because justifying the code seems to boggle me.

def count_ratings(st):
   count_list = [0,0,0,0,0]
   for i in st:
   if st == "*":
         count_list[0] = count_list[0] + 1

   elif st == "**":
         count_list[1] = count_list[1] + 1
   elif st == "***":
         count_list[2] = count_list[2] + 1

   elif st == "****":
         count_list[3] = count_list[3] + 1  
   else:
        if st == "*****":
         count_list[4] = count_list[4] + 1
   return count_list
def print_ratings():
   ratings = ["*****", "***", "**", "*****", "****", "**", "*", "***","**","*","**","*","*****","****","*****"]
   count_ratings(ratings)
   for i in count_list:
     print (count_list)
def main(): # defining the main
   process_user_word() # calling the process user word
   print_ratings()
main()

Answer 1

Three bugs with your code:

1. count_list is not defined in print_ratings() because you're using it within the scope of a different function, count_ratings() One approach to fixing this can be to bring the count_list into print_ratings() , and then passing it as an argument into count_ratings() .

2. When you use a for-each loop in python, ex. for i in st , i is the individual element, and st is the array. So in count_ratings() , all your if-clauses should use i instead of st .

3. process_user_word() is not defined. Not sure if you didn't provide it on purpose or not.

Here's the working code:

def count_ratings(st, count_list):
   for i in st:
      if i == "*":
         count_list[0] = count_list[0] + 1
      elif i == "**":
         count_list[1] = count_list[1] + 1
      elif i == "***":
         count_list[2] = count_list[2] + 1
      elif i == "****":
         count_list[3] = count_list[3] + 1  
      else:
         if i == "*****":
            count_list[4] = count_list[4] + 1

   return count_list

def print_ratings():
   ratings = ["*****", "***", "**", "*****", "****", "**", "*", "***","**","*","**","*","*****","****","*****"]
   count_list = [0,0,0,0,0]
   count_list = count_ratings(ratings, count_list)

   for i in count_list:
     print(count_list)

def main(): # defining the main
   print_ratings()

main()