emileypalmquist / python-p3-oxford-comma-lab

Oxford Comma Lab

Learning Goals

• Convert data types
• Practice iterating through lists
• Use various methods to manipulate lists and strings

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Key Vocab

• Interpreter: a program that executes other programs. Python programs require the Python interpreter to be installed on your computer so that they can be run.
• Python Shell: an interactive interpreter that can be accessed from the command line.
• Data Type: a specific kind of data. The Python interpreter uses these types to determine which actions can be performed on different data items.
• Exception: a type of error that can be predicted and handled without causing a program to crash.
• Code Block: a collection of code that is interpreted together. Python groups code blocks by indentation level.
• Function: a named code block that performs a sequence of actions when it is called.
• Scope: the area in your program where a specific variable can be called.

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Converting Types

In Python, there are a few methods available to us for converting data types. For example, it is possible to convert an integer into a float, a string that represents a number into a number type, and a string into a list or a list into a string, among other conversions. In this lesson we'll learn about converting between lists and strings, but you can learn about more of them in this tutorial on converting data types in Python.

String to List

To convert a string into a list, we can use the .split method:

"Hello World!".split()
# => ["Hello", "World!"]

The .split method uses whitespace as the separator by default. If we want to use a different separator, we can pass it as an argument:

"hippo,giraffe,monkey,horse".split(",")
# => ["hippo", "giraffe", "monkey", "horse"]

List to String

We can use Python's .join method to convert a list to a string. The syntax for the command is:

separator.join(items-to-join)

The method is called on a string which represents the separator you want to be inserted between each of the items in the list. If you want to join the items into a single string without any separators, you would call the method on an empty string:

''.join(["a", "b", "c"])
# => "abc"

On the other hand, if we want to separate each item in our list with a " :-) " ("smiley face"), we would do this:

" :-) ".join(["a", "b", "c"])
# => "a :-) b :-) c"

Instructions

To get started, run pipenv install to create your virtual environment and pipenv shell to enter the virtual environment. Then run pytest -x to run your tests. Use these instructions and pytest's error messages to complete your work in the lib/ folder.

Write a function oxford_comma() in the lib/oxford_comma.py file that takes an array of string elements as an argument and converts it into a string using the Oxford comma.

oxford_comma(["fiddleheads", "okra", "kohlrabi"])
# => "fiddleheads, okra, and kohlrabi"

Hint: You will need to refer to the section above about converting lists into strings, but note that coding this function will involve a couple of extra challenges.

This might be a challenging lab, so take your time using Google and playing around with your code. Good luck and have fun!

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Resources

• Wikipedia: Serial Comma
• DigitalOcean: How to Convert Data Types in Python 3