chapter 9 week 5 quiz

chapter 9 week 5 quiz

Quiz

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1. How are Python dictionaries different from Python lists?
   
   1.   Python lists store multiple values and dictionaries store a single value
   2.   Python lists are indexed using integers and dictionaries can use strings as indexes
   3.   Python dictionaries are a collection and lists are not a collection
   4.   Python lists can store strings and dictionaries can only store words
2. What is a term commonly used to describe the Python dictionary feature in other programming languages?
   
   1.   Closures
   2.   Associative arrays
   3.   Lambdas
   4.   Sequences
3. What would the following Python code print out?
   stuff = dict()
   print(stuff['candy'])
   1.   The program would fail with a traceback
   2.   -1
   3.   candy
   4.   0
4. What would the following Python code print out?
   stuff = dict()
   print(stuff.get('candy',-1))
   1.   0
   2.   The program would fail with a traceback
   3.   'candy'
   4.   -1
5. (T/F) When you add items to a dictionary they remain in the order in which you added them.
   
   1.   False
   2.   True
6. What is a common use of Python dictionaries in a program?
   
   1.   Building a histogram counting the occurrences of various strings in a file
   2.   Sorting a list of names into alphabetical order
   3.   Splitting a line of input into words using a space as a delimiter
   4.   Computing an average of a set of numbers
7. Which of the following lines of Python is equivalent to the following sequence of statements assuming that counts is a dictionary?
   if key in counts:
   counts[key] = counts[key] + 1
   else:
   counts[key] = 1
   1.   counts[key] = counts.get(key,0) + 1
   2.   counts[key] = (key in counts) + 1
   3.   counts[key] = key + 1
   4.   counts[key] = (counts[key] * 1) + 1
8. In the following Python, what does the for loop iterate through?
   x = dict()
   ...
   for y in x :
   ...
   1.   It loops through the keys in the dictionary
   2.   It loops through the values in the dictionary
   3.   It loops through the integers in the range from zero through the length of the dictionary
   4.   It loops through all of the dictionaries in the program
9. Which method in a dictionary object gives you a list of the values in the dictionary?
   
   1.   each()
   2.   all()
   3.   items()
   4.   values()
10. What is the purpose of the second parameter of the get() method for Python dictionaries?
    
    1.   An alternate key to use if the first key cannot be found
    2.   To provide a default value if the key is not found
    3.   The key to retrieve
    4.   The value to retrieve