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3.10-3.11 Lists and Searches

Basic Operations

#Defining the List
aList= [1,4,2,6,7,3,]
# Accessing Elements in a list
print(aList[1])


#Storing Element at an Index to a variable
Element = aList[3]
print(Element)


#Setting an Element at an Index to a variable
element = 4
aList[5]= element
print(aList[5])

#Insert a value at a certain index
aList.insert(3, 10)
print(aList[3])

#Adding another value to the list (append)
aList.append(5)
print(aList)

#Removing a value from the List at a specific Index
aList.remove(2)
print(aList)

#Accessing the Length of a list
print(len(aList))



4
6
4
10
[1, 4, 2, 10, 6, 7, 4, 5]
[1, 4, 10, 6, 7, 4, 5]
7

PopCorn hack #1

  • Create and define your own list and insert a value at a certain index
# Enter code here

list = [5, 6, 1, 7, 5]
list.insert(4, 5)
print(list)

[5, 6, 1, 7, 5, 5]

Finding the Minimum Value in a List

nums = [30, 45, 95, 56, 73, 98, 25]
min_value = nums[4]  # Start with the first element as the minimum

for score in nums:
    if score < min_value:
            min_value = score


print(min_value)  # Display the minimum value

25

PopCorn hack #2

  • Using the code above try to find the maximum value in the list
list = [30, 45, 95, 56, 73, 98, 25]
maxValue = list[4]

for score in list:
    if score > maxValue:
            maxValue = score

print(maxValue)

98

Sum of Even Numbers in a list solution

# Defining numbers in list
nums = [7, 5, 10, 6, 9, 4, 3, 12]
sum_even = sum([score for score in nums if score % 2 == 0])  # Using for loop to work through each number in the list and using mod to interpret if any numbers have a remainder of 0
print(sum_even)

32

Determining Outputs for code Segments with Length function

#Defining the list
words = ['old', 'computer', 'science', 'far', 'potato']
new_words = []
for word in words:
    if len(word) != 3: #if the length of the word is not equal to three
        new_words.append(word)  #adds it to a new list if the length is not equal to three

print(new_words)

['computer', 'science', 'potato']

If Else Statements with Lists

  • index: organizing the data by assigning a reference value to each element
  • Put the number is order either ascending or descending
  • Search starts with middle number first which is found by adding the highest and lowest index number and dividing it by 2
  • This divides the range by 2
  • Repeat this process by shrinking the range each time till the desired target is found
  • Every time the process is repeated and leads to a target it is considered a comparison
  • Each element in a list is examined in the order of the first element till the desired target
  • Order doesn’t matter

Homework Hack 1

  • What will be the middle index number in a Binary Search given the set of number: 3, 6, 12, 14, 50, 53
  • Which of the following lists can a Binary Search be used to find the desired target
  • This is a multiple choice question
fruits = ['Apple', 'Carrot', 'Mango', 'Peach']
A = [1, 3, 5, 8, 9, ]
B = [6, -1, 5, 12, 8]

# binary search doesn't work for the fruits
    # but B works on A
# the middle index would be 2

Homework Hack 2

  • Given a provided list perform two of the basic operations
list = [8, 10, 35, 39, 49, 52]
list.remove(35)
list.append(2)
print(list)

[8, 10, 39, 49, 52, 2]