max() and min() in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the max() function do in Python?

The max() function returns the largest item from an iterable or the largest of two or more arguments.

beginner

What does the min() function do in Python?

The min() function returns the smallest item from an iterable or the smallest of two or more arguments.

beginner

How can you find the maximum number in a list [3, 7, 2, 9]?

Use max([3, 7, 2, 9]) which will return 9.

beginner

How can you find the minimum value among numbers 5, 10, and 1?

Use min(5, 10, 1) which will return 1.

intermediate

Can max() and min() be used with strings? How?

Yes! They compare strings alphabetically (based on Unicode). For example, max(['apple', 'banana', 'cherry']) returns 'cherry' because 'c' comes after 'a' and 'b'.

What will max([4, 9, 1, 7]) return?

A 4

B 7

C 9

D 1

max() returns the largest number, which is 9.

What does min('dog', 'cat', 'bat') return?

A 'bat'

B 'cat'

C 'dog'

D Error

Strings are compared alphabetically. 'bat' comes before 'cat' and 'dog'.

Which of these is a valid way to use max()?

A max(3, 5, 2)

B All of the above

C max('a', 'z', 'm')

D max([3, 5, 2])

All options are valid uses of max().

What will min([]) do?

A Raise a ValueError

B Return None

C Return 0

D Return an empty list

min() raises a ValueError if given an empty iterable.

How does max() decide which item is largest when given strings?

A By string length

B Randomly

C By number of vowels

D Alphabetically (Unicode order)

max() compares strings alphabetically using Unicode order.

Explain how to use max() and min() with a list of numbers.

Think about finding the highest and lowest scores in a game.

Describe what happens if you use max() or min() on strings.

Think about dictionary order.

Practice

1. What does the max() function do in Python?

easy

A. Finds the largest item in a list or among values

B. Finds the smallest item in a list or among values

C. Sorts the list in ascending order

D. Removes duplicates from a list

Solution

1. Step 1: Understand the purpose of max()

   The max() function is used to find the biggest or largest item from a list or multiple values.

2. Step 2: Compare with other options

   Options A, C, and D describe different functions or actions, not what max() does.

3. Final Answer:

   Finds the largest item in a list or among values -> Option A

4. Quick Check:

   max() = largest item [OK]

Hint: max() returns the biggest value from inputs [OK]

Common Mistakes:

• Confusing max() with min()
• Thinking max() sorts the list
• Assuming max() removes duplicates

2. Which of the following is the correct way to find the minimum value in a list named nums?

easy

A. minimum(nums)

B. min(nums)

C. nums.min()

D. min = nums

Solution

1. Step 1: Recall the syntax of min()

   The correct syntax to find the smallest value in a list is min(list_name). So, min(nums) is correct.

2. Step 2: Check other options for errors

   minimum(nums) uses a non-existent function minimum(). nums.min() tries to call min() as a method on the list, which is invalid. min = nums assigns min to the list, which is incorrect usage.

3. Final Answer:

   min(nums) -> Option B

4. Quick Check:

   min(list) = smallest value [OK]

Hint: Use min(list_name) to get smallest value [OK]

Common Mistakes:

• Using min as a method like nums.min()
• Trying to assign min to a variable incorrectly
• Using a wrong function name like minimum()

3. What is the output of this code?

numbers = [3, 7, 2, 9, 5]
print(max(numbers))
print(min(numbers))

medium

A. 9 and 2

B. 3 and 5

C. 7 and 2

D. Error

Solution

1. Step 1: Identify the list values

   The list numbers contains [3, 7, 2, 9, 5].

2. Step 2: Find max and min values

   The largest value is 9 and the smallest value is 2.

3. Final Answer:

   9 and 2 -> Option A

4. Quick Check:

   max = 9, min = 2 [OK]

Hint: max() and min() find biggest and smallest values [OK]

Common Mistakes:

• Mixing up max and min results
• Assuming print shows the whole list
• Syntax errors from missing parentheses

4. The following code gives an error. What is the problem?

values = [10, 20, 30]
print(max(values, key=abs))

medium

A. The key function abs() is unnecessary here

B. max() cannot be used with lists

C. The code runs without error and prints 30

D. abs() is not defined

Solution

1. Step 1: Understand max() with key parameter

   The key parameter lets max() compare items by a function result. Here, abs returns absolute values, which are the same as the original values since all are positive.

2. Step 2: Check if code runs correctly

   Since abs is a built-in function and the list is valid, the code runs without error and returns the largest value, 30.

3. Final Answer:

   The code runs without error and prints 30 -> Option C

4. Quick Check:

   max(values, key=abs) = 30 [OK]

Hint: max() with key=abs works fine; abs() is built-in [OK]

Common Mistakes:

• Thinking abs() is undefined
• Believing max() can't use key parameter
• Assuming code causes error

5. Given the list words = ['apple', 'banana', 'grape', 'kiwi'], which code finds the word with the shortest length?

hard

A. max(words)

B. max(words, key=len)

C. min(words)

D. min(words, key=len)

Solution

1. Step 1: Understand the key parameter with len()

   Using key=len tells min() to compare words by their length, not alphabetically.

2. Step 2: Identify shortest word

   Among the words, 'kiwi' has the shortest length (4 letters). So min(words, key=len) returns 'kiwi'.

3. Final Answer:

   min(words, key=len) -> Option D

4. Quick Check:

   min by length = 'kiwi' [OK]

Hint: Use min(list, key=len) to find shortest string [OK]

Common Mistakes:

• Using max() instead of min() for shortest
• Not using key=len and getting alphabetical result
• Assuming min(words) finds shortest word