This Python Challenges lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
Write a function that returns the highest score in a list. Then change it so an empty list returns None instead of raising an error.
The starter below returns the highest of three scores.
Example 1: Start here
max of an empty list raises ValueError. The guard avoids that.
def highest(scores): # define the function; it runs when you call it
if not scores: # run the indented lines only when this is true
return None # send this value back to the caller
return max(scores) # send this value back to the caller
print(highest([71, 90, 82]))
print(highest([]))
Example 2: Highest, including an empty list
Check for an empty list before you call max.
def highest(scores): # define the function; it runs when you call it
if not scores: # run the indented lines only when this is true
return None # send this value back to the caller
return max(scores) # send this value back to the caller
print(highest([71, 90, 82]))
print(highest([]))
Example 3: Count the passes
Add 1 for every score that passes.
def passes(scores): # define the function; it runs when you call it
return sum(1 for score in scores if score >= 80) # send this value back to the caller
print(passes([71, 90, 82]))
Example 4: Reverse the words
reversed walks the list from the end. list turns that walk into a new list.
def flip(words): # define the function; it runs when you call it
return list(reversed(words)) # send this value back to the caller
print(flip(["Python", "SQL", "Git"]))
max of an empty list raises ValueError. The guard avoids that.
