lists 2

Question 2

what does .insert do

Answer 2

A list method to insert a specific index in a list

Question 3

what 2 inputs are used for .insert

Answer 3

1. The index you want to insert into.

2.The element you want to insert at the specified index.

example

store_line = [“Karla”, “Maxium”, “Martim”, “Isabella”]

store_line.insert(2, “Vikor”)
print(store_line)

output: = [‘Karla’, ‘Maxium’, ‘Vikor’, ‘Martim’, ‘Isabella’]

Question 4

What is the function of .pop

Answer 4

A list method to remove a specific index or from the end of the list

Question 5

what is the single input .pop requires

Answer 5

The index for the element you want to remove.

example:

[‘Python’, ‘Data Structures’, ‘Balloon Making’, ‘Algorithms’]

cs_topics.pop(2)
print(cs_topics)

Would output:

[‘Python’, ‘Data Structures’, ‘Algorithms’]

Question 6

how do we find what element was deleted using .pop

Answer 6

imply assign a variable to the call of the .pop() method. In this case, we assigned it to removed_element.

example:

removed_element = cs_topics.pop()
print(cs_topics)
print(removed_element)

Would output:

[‘Python’, ‘Data Structures’, ‘Balloon Making’, ‘Algorithms’]

‘Clowns 101’

We don’t have to save the removed value to any variable if we don’t care to use it later.

Question 7

how do we target the end of a list using .pop

Answer 7

dont add any index number in the .pop just keep it .pop()

Question 8

what is range() method

Answer 8

Creates a sequence of intagers

Question 9

how do you create a range

Answer 9

So, if we want the numbers from 0 through 9, we use range(10) because 10 is 1 greater than 9:

my_range = range(10)
print(my_range)

Would output:

range(0, 10)

Question 10

how do we make it so the range object becomes a list when we print it

Answer 10

The list() function takes in a single input for the object you want to convert.

We use the list() function on our range object like this:

print(list(my_range))

Would output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Question 11

what inputs can you give a .range( ?, ?, ? )

Answer 11

If we use a third input, we can create a list that “skips” numbers.

For example, range(2, 9, 2) will give us a list where each number is 2 greater than the previous number:

my_range2 = range(2, 9, 2)
print(list(my_range2))

Would output:

[2, 4, 6, 8]

Question 12

what is the len() function

Answer 12

we’ll need to find the number of items in a list, usually called its length.

We can do this using a built-in function called len().

Question 13

how do we apply the len( ) function

Answer 13

When we apply len() to a list, we get the number of elements in that list:

my_list = [1, 2, 3, 4, 5]

print(len(my_list))

Would output:

5

Question 14

how do you Calculate the length of list and save it to a variable

Answer 14

long_list = [1, 5, 6, 7, -23, 69.5, True, “very”, “long”, “list”, “that”, “keeps”, “going.”, “Let’s”, “practice”, “getting”, “the”, “length”]

ong_list_len = len(long_list)
print(long_list_len)

Question 15

what is slicing a list

Answer 15

In Python, often we want to extract only a portion of a list. Dividing a list in such a manner is referred to as slicing.

Question 16

how do you slice a list

Answer 16

• We can do this using the following syntax: letters[start:end], where:

1. start is the index of the first element that we want to include in our selection. In this case, we want to start at “b”, which has index 1.
2. end is the index of one more than the last index that we want to include. The last element we want is “f”, which has index 5, so end needs to be 6. index needs to be one above the number you want to end on

Question 17

explain example of slice

Answer 17

Take the list fruits as our example:

fruits = [“apple”, “cherry”, “pineapple”, “orange”, “mango”]

If we want to select the first n elements of a list, we could use the following code:

fruits[:n]

For our fruits list, suppose we wanted to slice the first three elements.

The following code would start slicing from index 0 and up to index 3. Note that the fruit at index 3 (orange) is not included in the results.

print(fruits[:3])

Would output:

[‘apple’, ‘cherry’, ‘pineapple’]

Question 18

what does .count method do

Answer 18

counts occurrences of an item in a list.

Question 19

how to use .count

Answer 19

letters = [“m”, “i”, “s”, “s”, “i”, “s”, “s”, “i”, “p”, “p”, “i”]

If we want to know how many times i appears in this word, we can use the list method called .count():

num_i = letters.count(“i”)
print(num_i)

Would output:

4

Question 19

how can you use .count() to count element appearances in a two-dimensional list.

Answer 19

Let’s use the list number_collection as an example:

number_collection = [[100, 200], [100, 200], [475, 29], [34, 34]]

If we wanted to know how often the sublist [100, 200] appears:

num_pairs = number_collection.count([100, 200])
print(num_pairs)

Question 20

what does .sort do

Answer 20

Often, we will want to sort a list in either numerical (1, 2, 3, …) or alphabetical (a, b, c, …) order.

We can sort a list using the method .sort().

Question 21

what does .sort(reverse=True)

Answer 21

.sort() also provides us the option to go in reverse. Instead of sorting in ascending order like we just saw, we can do so in descending order.

names.sort(reverse=True)
print(names)

Question 22

what does sorted do ( different to .sort )

Answer 22

it comes before a list, instead of after as all built-in functions do.
It generates a new list rather than modifying the one that already exists.

Question 23

what does the .zip function do

Answer 23

The zip() function allows us to quickly combine associated data-sets without needing to rely on multi-dimensional lists.

The zip() function takes two (or more) lists as inputs and returns an object that contains a list of pairs. Each pair contains one element from each of the inputs.

Question 24

why would the output show a list of random letters and numbers

names_and_heights = zip(names, heights)
print(names_and_heights)

Answer 24

zip object at 0x7f1631e86b48>

This zip object contains the location of this variable in our computer’s memory.

Question 25

How would be convert the random letters and numbers outputed by using the .zip function using list

Answer 25

it is fairly simple to convert this object into a useable list by using the built-in function list():

converted_list = list(names_and_heights)
print(converted_list)

Outputs:

[(‘Jenny’, 61), (‘Alexus’, 70), (‘Sam’, 67), (‘Grace’, 64)]

Question 26

how would we use .zip to combine two data sets

Answer 26

data set:
names = [“Jenny”, “Alexus”, “Sam”, “Grace”]
heights = [61, 70, 67, 64]

solution:
names_and_heights = zip(names, heights)

Question 27

why does the .zip create round brackets instead of square brackets

[(‘Jenny’, 61), (‘Alexus’, 70), (‘Sam’, 67), (‘Grace’, 64)]

Answer 27

1.Our data set has been converted from a zip memory object to an actual list (denoted by [ ])

2.Our inner lists don’t use square brackets [ ] around the values. This is because they have been converted into tuples (an immutable type of list).

Question 28

what is a tuples in python

Answer 28

Python tuples are a type of data structure that is very similar to lists. The main difference between the two is that tuples are immutable, meaning they cannot be changed once they are created. This makes them ideal for storing data that should not be modified, such as database records.