Dictionary and Sets

Question 1

What is a dictionary?

Answer 1

An object that stores a collection of data.

Question 2

A dictionary has two parts. What are they?

Answer 2

key

value

Question 3

How can you locate a specific value

Answer 3

using key.

Question 4

Webster analogy

Answer 4

words = keys
definition = values

Question 5

Key-Value pairs are often referred as?

Answer 5

Mappings

Question 6

Why is key-value pairs referred as mappings?

Answer 6

Because each key is mapped to a value

Question 7

Create a simple dictionary and explain..

Answer 7

lastname = {‘Ryan’: ‘Higa’, ‘Hanna’ : ‘Martin’, ‘Justin : Timber’}
»> lastname
»> lastname [‘Ryan’] –ryan = key
then it gives u value lastname : Higa.

Question 8

Keys must be what?

Answer 8

immutable objects. cannot be lists

Question 9

Syntax for adding new elements

Answer 9

phonebook[‘Sakura’] = ‘Tokyo, Japan’

Question 10

Can you have duplicate keys in the dictionary?

Answer 10

Nope. Even if you do it will just replace.

Question 11

Syntax for deleting?

Answer 11

del phonebook[“Sakura”]

Question 12

Syntax for checking if sakura is in the dictionary

Answer 12

if ‘Sakura’ not in phonebook
print(“Sorry not in the set”)
if ‘Sakura’ in phonebook
print(“In the phonebook”)

Question 13

How do you get the number of elements in a dictionary?

Answer 13

using len function.

Eg. len(phonebook)

Question 14

How do you create an empty dictionary?

Answer 14

dictionaryname = {} or dict()

Question 15

syntax for using loop and printing something in a dictionary

Answer 15

for key in phonebook:
print(key) #for key
print(phonebook[key]) # for value

Question 16

What does the clear method do?

Answer 16

It clears all the elements of the dictionary

phonebook.clear()

Question 17

What does the get method do?

Answer 17

gets a value from the dictionary.

Question 18

Will it raise an exception is key is not found?

Answer 18

No, the method returns default.

Question 19

How to print everything in dictionary

Answer 19

phonebook.items()

Question 20

How to print only the keys

Answer 20

phonebook.keys()

Question 21

how to print only the values

Answer 21

phonebook.values()

Question 22

What is a set?

Answer 22

A set is a collection of unique values and works like a mathematical set.

Question 23

Name the rules of set.

Answer 23

All the elements in the set must be unique
they are unordered.
the elements can be of different data types.

Question 24

How do you create a set?

Answer 24

must use a built in function

myset = set()

Question 25

How do you create an empty set?

Answer 25

myset = set()

Question 26

How do you create a set with a,b,c?

Answer 26

myset = set(['a','b','c'])

Question 27

What happens if you create a set like this : myset('aabbc')

Answer 27

well the repeating wont be in a set. Instead just this : a,b,c

Question 28

How to get the number of elements in the set?

Answer 28

len(myset)

Question 29

How to add 1 and 2 to myset?

Answer 29

myset. add(1) | myset. add(2)

Question 30

How to add 4,5,6,7,8,9 to myset?

Answer 30

myset.update([4,5,6,7,8,9)]

Question 31

How to remove a, b and c from myset?

Answer 31

myset. remove('a') myset. remove('b') myset. remove('c')

Question 32

How to remove all the items from myset?

Answer 32

myset.clear()

Question 33

How to print all the elements from myset using loops (for loop)?

Answer 33

for count in myset: | print (count)

Question 34

newset = set([1,2,3]) | Check if 1 is in the newset and print if found

Answer 34

if 1 in newset: | print("Found")

Question 35

newset = set([1,2,3]) | Check if 7 is in the newset and print if not found

Answer 35

if 7 not in newset: | print("Not found")

Question 36

Find the union of the following sets: set1=set([1,2,3]) set2=set([3,4,5])

Answer 36

set3=set1.union(set2)

Question 37

Find the intersection of the following sets: set1=set([1,2,3]) set2=set([3,4,5])

Answer 37

set3=set1.intersection(set2)

Question 38

Find the difference of the following sets set1=set([1,2,3]) set2=set([3,4,5])

Answer 38

set3=set1.difference(set2) | it will print 1,2

Question 39

Find the symmetric difference of the following sets : set1=set([1,2,3]) set2=set([3,4,5]) Also what will be the output?

Answer 39

set1.symmetric_difference(set2) output: 1,2,4,5

Question 40

What is another way of finding symmetric difference ? | Using what operator?

Answer 40

^ | set1 ^ set2

Question 41

How to find the subset of the following sets : set1 = set[(1,2,3,4)] set2=set[(2,3)]

Answer 41

set2.issubset(set1) | Output : True

Question 42

What does set1.issubset(set2) return?

Answer 42

False.

Question 43

How to find the superset of the following sets : set1 = set[(1,2,3,4)] set2=set[(2,3)]

Answer 43

set1.issuperset(set2)

Question 44

Another way to find if set2 is a subset of set1?

Answer 44

set2 <= set1

Question 45

Another way to find if set2 is SUPERSET Of set1?

Answer 45

set2 >= set1

Question 46

When you execute this : what are the elements stored? | myset = set ('Jupiter')

Answer 46

j,u,p,i,t,e,r | not ordered of course

Question 47

How to store "JUPITER"

Answer 47

myset = set(['Jupiter'])

Question 48

What is the difference between discard and remove in set?

Answer 48

remove raises a KeyError Exception whereas discard does not.

Question 49

What is serializing an object?

Answer 49

It is the process of converting the object to a stream of bytes that can be saved to a file for later retrieval.

Question 50

What is object serialization in phyton known as?

Answer 50

pickling

Question 51

Explain the steps to pickle/ serialize an object :

Answer 51

- Open a binary file for writing - call the pickle model's method dump for pickling object n write it to a special file - close the file after pickling.

Question 52

What is the mode for binary writing?

Answer 52

'wb'

Question 53

Syntax for pickling

Answer 53

``` import pickle dic = {"Peter" : "Spiderman", "Kitty" : "Shadowcat"} outputfile = open ("file.dat", "wb") pickle.dump = (dic, outputfile) outputfile.close() ```

Question 54

What is the mode for binary reading?

Answer 54

"rb"

Question 55

Syntax for unpickling

Answer 55

``` import pickle read = open ("data.dat". "rb") a = pickle.load(infile) print a read.close() ```