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Python Sequences

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Len, Min, and Max

3:04 with Ashley Boucher

Get important information about your Python sequences with the functions `len`, `min`, and `max`.

Lexicographical ordering is very similar to alphabetical ordering, but it considers additional characters besides the letters of the alphabet.

Some of the basic rules in Python are that:

  1. Uppercase letters come earlier than lowercase letters. This means that A < Z < a < z.

  2. Numbers come earlier than letters. This means that 0 < 9 < A < a.

  3. Space characters come before all printable characters.

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    In this video, we're gonna discuss some more Python functions that are common to 0:00
    all sequences, len, min, and max. 0:03
    These three functions are built-in Python functions that all receive one argument, 0:06
    an iterable. 0:10
    Len, for length, will return the length of the passed sequence. 0:11
    Min will return the smallest element in the sequence, and 0:14
    max will return the largest. 0:17
    Min and max works for all sequences, even strings, but 0:19
    only if every element in the sequence is of the same type. 0:22
    If you try to determine the max element in a sequence that contains both strings and 0:25
    integers, you'll get an error. 0:29
    We'll start with len. 0:31
    Len is a very useful function you'll probably use quite often. 0:32
    I'm gonna copy and paste in a simple sequence, 0:35
    a tuple where the elements are the numbers 1 through 10. 0:37
    To get the length of nums, that is the number of elements inside nums, 0:42
    the code is len(nums). 0:48
    Great, it returned 10, just like we knew already. 0:51
    To obtain the max or the largest element in the sequence, we use the max function. 0:55
    Also 10, it's the largest integer in the sequence. 1:03
    And then, min. 1:06
    It returns 1, the smallest integer in the sequence. 1:10
    Now, these functions don't just work with lists and tuples. 1:13
    They're common to all Python sequences. 1:16
    Let's take a look at how they work with strings. 1:18
    How many characters are in our string? 1:26
    The len function will tell us. 1:28
    Looks like there are 9. 1:33
    Max and min for strings works by finding the characters closest to the end and 1:35
    the beginning of the alphabet, respectively. 1:39
    In this example, max returns u because it's closest to z, 1:46
    or the end of the alphabet. 1:49
    What do you think min will return? 1:51
    If you guessed e, you'd be right. 1:53
    But what happens if you have a string that also contains numbers, 2:00
    like this, for example? 2:03
    The 2019 in this string is not an integer, it's part of the string. 2:13
    But it's also probably not one you think of when you think of the alphabet. 2:17
    So how does the comparison work? 2:20
    Well, when comparing strings in all types of sequences, 2:22
    Python uses something called lexicographical ordering. 2:25
    See the teacher's notes for more information on this. 2:28
    But in this example, it's relevant to know that Python considers 2:30
    strings that are numbers to be smaller than strings that are letters. 2:33
    The max of this string will still be u, but the min will be different. 2:37
    As you can see, min returned the string 0. 2:51
    All right, now that you've tackled len, min and 2:54
    max, join me in the next video to learn about membership testing. 2:56
    Which is just a fancy term for finding out whether a sequence contains a given item. 3:00

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