Python Lists
Last updated
Last updated
After this lesson, you will be able to:
Create lists in Python.
Print out specific elements in a list.
Perform common list operations.
A list is Python's name for an array. They function very similarly to Javascript arrays.
If you want to access a specific element, you access it with bracket notations in the same way as Javascript. For example, to print 'Steve', we would write: print(my_class[2]).
len()To get the length of a list, use len(list_name). For example:
append()To add something on the end of a list, use list_name.append(item). For example:
insert()To add an element in a list at a specific index, use list_name.insert(index, item). For example:
pop()There are two ways to use pop(); with no parameters or with an index. If no parameter is set, pop() will remove the last item from a list and return it, otherwise it will remove the item at that specific index. For example:
Declare a list with the names of your classmates
Print out the length of that list
Add a new classmate
Print the 3rd name on the list
Delete the first name on the list
Move the last name on the list to be the second name
Answers ```python # 1. Declare a list with the names of your classmates classmates = ["James", "Tamis", "Parker", "Nhu", "Brad", "Q", "Kelly", "Paulo", "Doug"] # 2. Print out the length of that list print(len(classmates)) # 3. Add a new classmate classmates.append("Rome") print(classmates) # 4. Print the 3rd name on the list print(classmates[2]) # 5. Delete the first name on the list print(classmates.pop(0)) # 6. Move the last name on the list to be the second name classmates.insert(1, classmates.pop()) print(classmates) ```
These actions can only be used with lists of numbers.
sum()This is used when you want to add all the numeric items in your list. For example:
min() and max()These will find the smallest and largest number in your list. For example:
Declare a list of numbers
Print out the largest difference between numbers
Print the mean of all the numbers
Answers
```python # Declare a list of numbers numberz = [4, 10, 8, 9, 77, 21, 3, 4] # Print out the largest difference between numbers big_diff = max(numberz) - min(numberz) print(big_diff) # Print the mean of all the numbers avg = sum(numberz)/len(numberz) print(avg) ```
