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Python_List_Intro.py
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# This program shows the difference between a strings and lists | |
# with a quick introduction to using functions with a list | |
# This is my typical grocery list stored as one single STRING | |
grocery_list_for_Joe = ['eggs, milk, dandruff shampoo, holy grail, 2 african swallows, coconut'] | |
#print(grocery_list_for_Joe) | |
# Below is my grocery list created as a LIST instead of a STRING: | |
grocery_list_for_Joe = ['eggs', 'milk', 'dandruff shampoo', 'holy grail', '2 african swallows', 'coconut'] | |
#print(grocery_list_for_Joe) | |
# Creating a list takes a bit more than creating a string. | |
# But, a list is more useful than a string because it can be manipulated. | |
# For example, we can print the third item in our list (called the INDEX position) inside square brackets ([]): | |
#print(grocery_list_for_Joe[2]) | |
# WAIT! isn't this the third item on our list? Yes, but lists in Python are 0-based, meaning the first item in a list can be selected using syntax like [0]. | |
# If the first item in a list is [0], then the second item in the list [1] | |
# You can also switch out an item in the list much more easily than you could than w/ a string. | |
# Let's say I need yogurt instead of dandruff shampoo, I can easily replace it. | |
#grocery_list_for_Joe[2] = 'yogurt' | |
#print(grocery_list_for_Joe) | |
# now the item in index postion 2 in my list, is replaced with 'yogurt' | |
# I can also show a subset of the items in my list by using a colon (:) inside square brackets. | |
#For example, to see the third to sixth items in my list (items from Monty Python) I would type the following: | |
#print(grocery_list_for_Joe[3:6]) | |
# In other words, writing [3:6] is the same as saying "show the items from the index postion 3 up to index position 6" | |
# Or "show items 3, 4, 5" | |
# Lists can be used to store all sorts of items, like numbers: | |
some_numbers = [1, 2, 5, 10, 25] | |
#print(some_numbers) | |
#print(some_numbers[2]) | |
# ADDING ITEMS TO A LIST | |
# To add items to a list, we use the append function. | |
# Remember a function is a chunk of code that we can reuse, that tells Python to do something | |
# For this case, the append function adds items to the end a list | |
# For example, let's add the item, avocado, to the end of my grocery list: | |
grocery_list_for_Joe.append('avocado') | |
#print(grocery_list_for_Joe) | |
# You can keep adding to your grocery list | |
# I'm going to add three more items | |
grocery_list_for_Joe.append('dragon egg') | |
grocery_list_for_Joe.append('apple') | |
grocery_list_for_Joe.append('banana') | |
#print(grocery_list_for_Joe) | |
# To add items to our list, we used the APPEND function | |
# Remember, a function is a chunk of code that tells Python to perform a specific action | |
# The function we just used (append), adds an item to the end of a list. | |
# REMOVING ITEMS FROM A LIST | |
# Let's say I realize I already have an item in my grocery list | |
# To remove items from a list, use the del command (short for delete). | |
# For example, to remove the fifth item in grocery_list_for_Joe, coconut, write: | |
del grocery_list_for_Joe[5] | |
#print(grocery_list_for_Joe) | |
# Remember that postions in a list start at zero, so grocery_list_for_joe[5] refers to the sixth item in my grovcery list. | |
# I realized I don't need those items I just recently added (dragon egg, 2 african swallows, banana) | |
# So I am going to remove those items: | |
del grocery_list_for_Joe[4] | |
del grocery_list_for_Joe[5] | |
del grocery_list_for_Joe[6] | |
#print(grocery_list_for_Joe) | |
# LIST ARITHMETIC | |
# lists can also contain numbers and even store other lists | |
# We can join lists by adding them, just like with adding numbers, using a (+) sign. | |
# For example, suppose we two lists: list1, containing the numbers 1 through 4, and list2, containing some words. | |
# We can add them together using the print function and the + sign: | |
list1 = [1, 2, 3, 4] | |
list2 = ['I', 'tripped', 'over', 'and', 'hit', 'the', 'floor'] | |
#print(list1 + list2) | |
# We can also add the two lists and set the result equal to another variable. | |
list3 = ['I', 'ate', 'the', 'choclate', 'and', 'I', 'want', 'more'] | |
list4 = list1 + list3 | |
print(list4) | |
# So our new variable (list4) is equal to list1 and list3 together | |
# the above is an adapted version of Jason R. Briggs, from the book, Python For Kids | |
# from the chapter: Strings, Lists, Tuples and Maps |
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