Exam 2 Review for Python :(

dictionary

object that stores a collection of data

key

the immutable identity for the element in a dictionary

dictionary = {key1:value1}

format for creating a dictionary

false

true or false: dictionaries are sorted

dictionary[key]

general format for retrieving value from dictionary

true

true or false: a keyerror is returned if you call a dictionary with a nonexistent key

in

operator used to test whether a key is in a dictionary

true

true or false: dictionaries are mutable

dictionary[key]=value

format to add or change a key-pair value in a dictionary

del dictionary[key]

format to delete a key-value pair

len function

used to obtain number of elements in a dictionary

true

true or false: Values stored in a single dictionary can be of different types

dict()

built in function that creates an empty dictionary

clear method

deletes all the elements in a dictionary, leaving it empty

get method

gets a value associated with specified key from the dictionary

dictionary.get(key, default)

format for get method (returns default if key is not found)

items method

returns all the dictionaries keys and associated values; Each element in dictionary view is a tuple which contains a key and its associated value

keys method

returns all the dictionaries keys as a sequence

pop method

returns value associated with specified key and removes that key-value pair from the dictionary

dictionary.pop(key, default)

format for pop method; default is returned if key not found

popitem method

returns a randomly selected key-value pair as a tuple and removes that key-value pair from the dictionary

values method

returns all the dictionaries values as a sequence

set

object that stores a collection of data in same way as mathematical set

false

true or false: sets cannot have elements of different data types

set()

format of function used to create an empty set

‘a’,’b’,’c’

what a set contains if set(‘abc’) is passed

‘abc’

what a set contains if set([‘set’])

true

true or false: sets are mutable

add method

adds an element to a set

update method

adds a group of elements to a set

remove method

removes the specified item from the set WITH CAUSING A KEYERROR

discard method

removes the specified item from the set WITHOUT CAUSING A KEYERROR

clear method

clears all the elements of the set

union of two sets

a set that contains all the elements of both sets

set1.union(set2)

union method format

set1 l set2

operator for union method

intersection of two sets

a set that contains only the elements found in both sets

set1.intersection(set2)

format for intersection method

set1 & set2

operator for intersection method

difference of two sets

a set that contains the elements that appear in the first set but do not appear in the second set

set1.difference(set2)

difference method format

set1 - set2

difference method operator

Symmetric difference of two sets

a set that contains the elements that are not shared by the two sets

set1.symmetric_difference(set2)

symmetric_difference method format

set1 ^ set2

symmetric_difference method operator

subset

small set that is in a bigger set

superset

a large set that contains all the elements of a smaller set

setA.issubset(setB)

To determine whether set A is subset of set B

setA <= setB

To determine whether set A is subset of set B operator

setA.issuperset(setB)

To determine whether set A is superset of set B

setA >= setB

To determine whether set A is superset of set B operator

Serialize an object

convert the object to a stream of bytes that can easily be stored in a file (turning an object into computer words)

pickling

term meaning serializing an object

pickle

what you import to pickle and stuff

pickle.dump(object, file)

function to pickle objects to a file

unpickling

retrieving pickled object

pickle.load(file)

format to get pickled object from a file

{‘a’,’b’,’c’,’d’,’e’,’f’}

set1= {‘a’,’b’,’c’,’d’}

set2={‘c’,’d’,’e’,’f’}

set3=set1 | set2

{‘c’,’d’}

set1= {‘a’,’b’,’c’,’d’}

set2={‘c’,’d’,’e’,’f’}

set3=set1 & set2

{‘a’,’b’}

set1= {‘a’,’b’,’c’,’d’}

set2={‘c’,’d’,’e’,’f’}

set3=set1 - set2

{‘e’,’f’}

set1= {‘a’,’b’,’c’,’d’}

set2={‘c’,’d’,’e’,’f’}

set3= set2- set1

{‘a’,b’,’e’,’f’}

set1= {‘a’,’b’,’c’,’d’}

set2={‘c’,’d’,’e’,’f’}

set3=set1 ^ set2

sequence

an object that contains multiple items of data

list

an object that contains multiple data items and is mutible

list(object)

function converting objects to list

element

an item in a list

true

true or false lists can hold items of different types

list=[item1, item2, item3]

format for list assignment statement

repetition operator

makes multiple copies of a list and joins them together

index

a number specifying the position of an element in a list

0

index of first element in a list

-1

index of last element in a list

IndexError

raised if invalid index is used YOU CAN ONLY USE THE INDEX YOU HAVE

len function

returns the length of a sequence such as a list

eg: size = len(my_list)

mutable sequence

a sequence in which the items in the sequence can be changed

list[x] = new_value

format to assign a new value to a list element

concatenate

joining two things together

augmented assignment operator

+= used to concatenate lists

slice

a span of items that are taken from a sequence

list[start:end]

list slice format————-will not include end value

false

true or false, this will cause a IndexError

list=[1,2,3,4,5,6,7,8]

print(list[0:20])

append(item)

METHOD used to add items to a list- item is appended to the end of the existing list

index(item)

METHOD returning the index of the first element in the list containing item

-raises ValueError if item not in the list

insert(index, item)

METHOD used to insert item at position index in the list

sort()

METHOD used to sort the elements of the list in ascending order

remove(item)

METHOD used to remove the first occurrence of item in list

reverse()

METHOD used to reverse the order of the elements in the list

del list[x]

STATEMENT removing an element from a specific index in a list

min(list)

FUNCTION returning the item that has the lowest value in a sequence

max(list)

FUNCTION returning the item that has the highest value in a sequence

two-dimensional lists

a list that contains other lists as its elements

tuple

an immutable sequence

tuple_name=(item1, item2)

tuple format assignment statement

tuple(list)

turns list into tuple

cookie

a small file that contains information about the browsing session

“writing data to”

saving data on a file

output file

a file that data is written to

“reading data from”

process of retrieving data from a file

input file

a file from which data is read

open the file, process the file, close the file

the three steps when a program uses a file