# Python Chapter 7 >>>

##Lists and Tuples

**Sequence** - an object that holds multiple items of data stored one after the other. You can perform operations on a sequence to examine and manipulate the items stored in it. (Java has atomic data)

**Lists and tuples are sequence types**

**List** is an object that contains multiple data items. It is mutable is an Array -  it is dynamic, items can be added and removed. You can use methods index, slice to work with them. It can hold different types.

    info = ['Jen', 7, 15.5]

    numbers = list(range(5))

**element** - each item in a List

**iteratable** - object?

**Tuple** is immutable is a Hash?

**repetition operator** - makes multiple copies of a list and joins them together
list * n  n is the repetition operator

print function can be used to display an entire list

list() function can convert certain types of objects to lists

Difference between Lists and Arrays - Arrays are more limited

###Iterating over a list

    numbers = [1,2,3,4]
    for n in numbers:
      print(n)

### Concatenating Lists

repetition operator

p.297

repetition operator
list1 = [a,b,c]
list2 = [1,2,3]
list3 = list1 + list2

print(list3)

>> [a,b,c,1,2,3]

**=+ (augmentation operator** - concatenates two lists and reassigns the variable on the left)

### List Slicing

p.299
When you slice a list you get a span of elements from within the list.

list_name[start : end]

start is inclusive
end is exclusive

##Iterate over a list with a for loop

    mylist = [1,2,3]
    for element in mylist:
      print(element * element)

## Indexing

first position - 0
last position - n-1

**try except structure block** - test to see if

Length of List - len(mylist)

    mylist = [1,2,3,4,5,6,7,8,9]
    index = 10
    if (index , len(mylist):
      print(mylist[index])
    else:
      print("The index is too large.")

**smallest negative index** - -n elements

## Finding Items in Lists with the *in operator*

## List methods and built-in functions

**append(item)** - p.303 used to add items to a list

**index(item)** - p.305

**insert(index, item)** - p.307

**sort()** - p.307

**remove(item)** - p.308

**reverse()** - p.309

## The del Statement

    *mylist = [1,2,3,4,5,6]
    print('Before deletion', mylist)
    del_mylist[2]
    print('After deletion', mylist)

**** -

**** -

    NUM_DAYS = 5
    sales = [0] * NUM_DAYS
    index = 0
    print("Enter the sales for the day: >>")
    while index < NUM_DAYS:
      print('Days' index + 1, ":", sep=' ', end=' ")
      sales[index] = float(input())
      index += 1

    print("Here are the sales for the days you entered: ")
    for value in sales:
      print(value)

with a for loop

    NUM_DAYS = 5
    sales = [0] * NUM_DAYS
    index = 0

    print("Enter the sales for the day: >>")

    for index in range(0, NUM_DAYS):
      print('Days' index + 1, ":", sep=' ', end=' ")
      sales[index] = float(input())
      index += 1

    print("Here are the sales for the days you entered: ")
    for value in sales:
      print(value)
Diana