Quiz 2 Endg 233

String

Sequence of characters that can be stored in a variable

String literal

string value specified in the source code of a program

Give an example of a string literal

any text in between quotation marks

The string type is a special construct known as a

sequence type

What is a sequence type

A type that specifies a collection of objects ordered from left to right

What is the index position of a string

The first character is at index 0, the second character is at index 1

How are strings assigned?

Strings can be assigned to variables just like other data types. For example, str1 = 'Hello' or str1 = str2

What is an Empty String?

An empty string is a sequence type with 0 elements, created using two quotes (e.g., my_str = '').

How do you find the length of a string?

The len() function is used to find the length (number of characters) of a string.

What does the len() function do?

It finds the number of characters in a string

How do you access characters in a string?

Index Positions, variable[index], —> this accesses the characters from left to right, negative numbers access characters from the right

What is String Concatenation?

It combines strings together (***without adding spaces)

What would ‘New’ + ‘York’ result in?

‘NewYork’

Are strings mutable?

Strings are immutable they cannot be changed in place. Instead a new string is created each time.

How do you make changes to a string if its immutable?

You create a new string with the desired modifications

What is an empty string

string with 0 characters, they are used as placeholders

Can you change individual characters in a string in Python? Why or why not?

No, you cannot change individual characters in a string in Python. Strings are immutable, meaning that once created, they cannot be altered in place. If you want to change a string, you create a new string with the desired modifications.

Unicode

Unicode is a character encoding standard that assigns a unique number (code point) to every possible character, including letters, numbers, symbols, and more. Python uses Unicode to represent characters as code points, allowing it to work with a wide range of characters from different languages and scripts.

Code Point

numerical value that represents a specific character in the Unicode standard

Escape Sequence

two item sequence in a string that represents a special character using a backlash followed by a specific character

What is \n

newline

\\

backslash

\’

single quote

\”

double quote

How do you create a raw string?

add an r before a string literal

Give an example of formatting a raw string

r’text’

What do raw strings do

escape sequences are treated as literal characters, not interpreted

what does the ord() function do?

returns the encoded integer value for a string of length one—> helpful in finding the numerical encoding of a character

what does the chr() function do

it returns a string of one character for an encoded integer —> you can convert an encoded value back into a character

What does ‘Jen\nJoe\\nMaya\\\nAlex’

Jen

Joe\nMaya\

Alex

What is a formatted string literal / f-string?

allows a programmer to create a string with placeholder expressions that are evaluated as the program executes

How do you start a formatted string?

f’blahblah’

What does the equal sign do in an f-string

it prints both the expression and the result Ex: f'{2*4=}' produces the string "2*4=8".

What do double braces do in an f-string?

They place a curly brace x: f'{{Jeff Bezos}}: Amazon' produces the string "{Jeff Bezos}: Amazon".

What does format specification inside a repacement field do?

Allows a values formatting in the string to be customized

How is a format specification introduced inside a replacement field

a colon is used to separate the WHAT from the HOW Ex: {4:.2f} formats 4 as 4.00.

What does a presentation type do in a format specification

determines how to represent a value in text form, such as an integer (4), a floating point (4.0), a fixed precision decimal (4.000), a percentage (4%), a binary (100), etc.

what does the format specification :s do?

string(can be omitted as it is defult)

what does the format specification :d do?

decimal(integer values only) 12:03d —> 012

what does the format specification :b do?

binary(integer values only)

what does the format specification :x/X do?

Hexadecimal in lowercase(x) and upper case(X) int values only

what does the format specification :e do?

exponent notation (e to the___)

what does the format specification :f do?

fixed point notation(six places of precision)

what does the format specification :.[precision]f do?

fixed-point notation(you can specify how many decimals!

what does the format specification :0[precision]d do?

leading 0 notation —> 4:03d would be 004

What is a container

construct used to group related values together and contains references to other objects instead of data

What is a list

a container created by surrounding a sequence of variables or literals with brackets [ ].

What is a list item called

An element

the index in a list

starts with 0

How do you access a specific item in a list

listname[index]

Are lists mutable?

Lists are mutable so, you can update list elements

How do you add an element to a list

list.append(value)

How do you remove an element from a list

list.pop(i) —> removes the element at index i from list

list.remove(value) —> removes the first element that is value

len(list)

length of list

list1+list2

Produce a new list by concatenating list2 to the end of list1.

min(list)

Find the element in the list with the smallest value. All elements must be of the same type

max(list)

Find the element in the list with the largest value. All elements must be of the same type.

sum(list)

Find the sum of all elements of a list (numbers only).

list.index(val)

Find the index of the first element in the list whose value matches val.

list.count(val)

Count the number of occurrences of the value val in the list.

Define tuple

stores a collection of data, like a list, but is immutable. supports len, indexing and other sequence functions

how is a tuple generated

creating a list of csv like (5,15,30)

When is a tuple used

Used when context of values is known ex latitude and longitude are always in a specific order

What is a set, and what are its properties

A set is an unordered collection of unique elements

• Elements are unordered: Elements in the set do not have a position or index.

• Elements are unique: No elements in the set share the same value.

What does the set() function do

it accepts a sequence-type iterable object(list, tuple,string)

How do you make a set literal?

{value,val,v} same can be done with set([1,2,3])

What happens if you pass a list into set()

it causes any duplicates to be omitted in the created set

What happens if you try to access an index in a set

RUNTIME error, there is no order!

What does remove() and pop() do to a set

removes a specific value, pop removes a random value

len(set)

number of elements in a set

set1.update(set2)

adds the elements in set2 to set1

set.add(value)

adds value into the set

set.remove(value)

removes value from the set

set.clear()

clears all elements from the set

set.intersection(a,b,c)

Returns a new set containing only the elements in common between set and all provided sets.

set.union(set_a, set_b, set_c...)

Returns a new set containing all of the unique elements in all sets.

set.difference(set_a, set_b, set_c...)

Returns a set containing only the elements of set that are not found in any of the provided sets.

set_a.symmetric_difference(set_b)

Returns a set containing only elements that appear in exactly one of set_a or set_b

Dictionaries include

Key:Value Pairs

curly braces to surround key:value pairs

createes dictionary contents

How to access dictionary entries

dictionary[key]

dict[k] = v

Adds a new key-value pair

del dict[k]

deletes value

Sequence types include

string, list, and tuple are containers for collections of objects ordered by position in the sequence

Mapping Type includes

dict type

Which types are immutable

tuple

Is a list invalid if it has multiple types?

No

Do dictionaries use the append function?

No

What is the syntax for tuples

parentheses

What is a membership operator

in and not in operators which yield True or False. Can be used to check if a string is a substring

Membership in dictionary

implies that a specific key exists in the dictionary, does not return value

What is an implicit conversion

type conversion automatically made by interpreter5.5

While loop

A while loop is a construct that repeatedly executes an indented block of code (known as the loop body) as long as the loop's expression is True.

sentinel value

a value that when evaluated by the loop expression causes the loop to terminate.

For loop

loops over each element in a container one at a time, assigning a variable with the next element that can then be used in the loop body.

How do you iterate a for loop backwards

for name in reversed(list)

range(Y)

sequence of all non-negative integers less than Y

range(X,Y)

Sequence of integers >=X and less than Y

range(X,Y,Z)

>=X and <Y, incrementing by Z

When should you use a for loop

when the number of iterations is computable or when accessing the elements of a container