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Python Dictionaries Exercises

4 exercises that build on the Python Dictionaries lesson, from easy to hard. Each one is checked in your browser when you press Check. Stuck? Use the hint before peeking at the solution.

What this lesson covers: A dictionary stores pairs of keys and values, so you can look up a value by a meaningful key, such as a name or an ID, instead of by its position. By the end you can create a dictionary, read values with [] and get(), add, change and delete entries, loop over keys and values, and count things with a dictionary. You will practise: Update the cafe menu; Predict the stock report; Fix the letter counter; Average grade per student.

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1. Update the cafe menu

Write code Easy

Change the menu dictionary: add "juice" with the price 2.75, change the price of "coffee" to 2.25, then print how many items the menu has.

Your code 
menu = {"tea": 1.5, "coffee": 2.0, "cake": 3.25}

# your code here





  
  

  
  
  



    
  
    

  

    
2. Predict the stock report

    Predict the output
    Medium
    
  

  
Read the code and type exactly what it will print. Then press Check to run it and compare.

  
    

  

    Read this code
    

      
      
    

  

  
stock = {"pens": 10, "pads": 4}
stock["pens"] = stock["pens"] - 3
stock["clips"] = 50
print(stock)
print(stock.get("tape", 0), len(stock))
for item in stock:
    print(item)

  
  
  

  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    

  
    

  

    
3. Fix the letter counter

    Fix the bug
    Medium
    
  

  
This code should count how many times each letter appears in word and print {'m': 1, 'i': 4, 's': 4, 'p': 2}, but it crashes with a KeyError. Fix it.

  
    

  

    Your code
    

      
      
      
      
    

  

  
word = "mississippi"
counts = {}
for letter in word:
    counts[letter] += 1
print(counts)

  
  
  
  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    
  
    

  

    
4. Average grade per student

    Write code
    Hard
    
  

  
grades maps each student to a list of marks. Build a new dictionary averages that maps each name to their average mark rounded to 1 decimal place. Then store the name of the student with the highest average in best and print Top student: <name>.

  
    

  

    Your code
    

      
      
      
      
    

  

  
grades = {"Asha": [88, 92, 79], "Ben": [65, 70, 58], "Chen": [95, 98, 91]}
averages = {}
best = ""

# fill averages, then find best


  
  
  
  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    
  
  

    Next lessonPython Dictionary Methods
    
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