Python Crash Course
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Common Functions and Methods in Lists

let's conclude our discussion on lists by discussing various functions associated with them.

Functions

As mentioned previously, a function is a piece of code that is called by name. It can be passed data to operate on and can optionally return data. Let's look at some examples of functions that can be applied to lists:

‍The len function

len simply returns the number of characters in a sequence.

numbers = [3, 5, 6, 7, 9] length_of_numbers = len( numbers ) print(length_of_numbers)

‍>> 5

The output as expected is 5, since that's how many elements we have in the list numbers .

‍The **max** function

max will return the greatest element in a list

numbers = [3, 5, 6, 7, 9] maximum_number = max( numbers ) print(maximum_number)

>> 9

  • W‍hat if we had a list of strings? how would max work then?
n‍ames = ["Thomas", "Gio", "Zack", "Adam"] print(max(names))

>> Zack

When dealing with max in a list of strings, the maximum value would be the string that appears last based on alphabetical order.

We can conclude that max works differently depending on which data type you're using with it.

What if the list has a mix of strings and numbers?

let's inject a number in our list:

n‍ames = ["Thomas", "Gio", "Zack", "Adam", 1] print(max(names))

TypeError: '>' not supported between instances of 'int' and 'str'

You get an error. The data types are incompatible.

‍The min function

Let's try the min function, and as you might have guessed, the min function will do the exact opposite of the max function.

n‍ames = ["Thomas", "Gio", "Zack", "Adam", 1] print(max(names))

‍>> Gio

It will return the string that shows up first, based on alphabetical order.

Intuitively, for integers, min would return the smallest value:

numbers = [3, 5, 6, 7, 9] minimum_number = min( numbers ) print(minimum_number)

‍>> 3

‍‍The sorted function

Another useful function that we can use for lists is sorted. sorted will take in a list as an argument and sort it from smallest to largest :

numbers = [3, 5, 6, 7, 9] sorted_number = sorted( numbers ) print(sorted_number)

>> [3, 5, 6, 7, 9]

we can do the same thing to our names list:

n‍ames = ["Thomas", "Gio", "Zack", "Adam"] sorted_names = sorted(names) print(sorted_names)

>‍> ['Adam', 'Gio', 'Thomas', 'Zack']

‍sorted will sort a list of words alphabetically.

‍Methods

As mentioned previously, a method is a function associated with an object. Let's look at some common methods in lists:

The join method

The join method is actually a string method that takes in as an argument a list of strings. What it's going to do is return a string consisting of every element on that list joined by the string.

joined_string = '-'.join(['january', 'february', 'march']) print(joined_string)

>> january-february-march

Instead of a hyphen -, you could also do a blank space.

joined_string = ' '.join(['january', 'february', 'march']) print(joined_string)

>> january february march

The format method

format replaces curly brackets { } in a string with any other string value:

formatted_string = "this person is {}, {}, and {}".format('tall', 'slim', 'blonde') print(formatted_string)

>> this person is tall, slim, and blonde

The append method

Another useful method is the append method. As the name suggests, you can use this method to append any value to a list.

months = ['January', 'February', 'March'] months.append('April') print(months)

>> ['January', 'February', 'March', 'April']

This concludes our discussion on lists. In the next article, we will have a look at tuples.

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