Dictionaries

Question 1

What types of lists, tuples, and strings can you convert to dicts?

Answer 1

dict([‘a’, ‘b’], [‘c’, ‘d’]) = {‘a’:’b’, ‘c’:’d’}
dict((‘a’, ‘b’), (‘c’, ‘d’)) = {‘a’:’b’, ‘c’:’d’}
dict(‘ab’, ‘cd’) = {‘a’:’b’, ‘c’:’d’}

Question 2

How to replace dict key x with ‘y’?

Answer 2

dict[x] = ‘y’

Question 3

Can you have {‘a’ : ‘b’, ‘a’ : ‘c’}?

Answer 3

No, dict keys need to be unique

Question 4

How do you merge dict x with dict y?

Answer 4

x.update(y)

It’s kinda like list.extend(y)

Question 5

How to delete a key:value?

Answer 5

del dict[key]

Question 6

How to delete everything from a dict?

Answer 6

dict.clear()

it’s a dict method

Question 7

how to see if ‘x’ is in dict?

Answer 7

‘x’ in dict

Gives boolean

Question 8

How do you get a key without an error function if it isn’t there?

Answer 8

dict.get(key, ‘it’s not there’)

Returns ‘it’s not there’ if key doesn’t exist

Question 9

How to get all keys in a list?

Answer 9

dict.keys()

Question 10

How to get all values in a list?

Answer 10

dict.values()

Question 11

How to get all items in a list as tuple items in a list?

Answer 11

list(dict.items())

Question 12

Difference between set and tuple?

Answer 12

set = {x, y}
tuple = (x, y)

Sets don’t have an order and are ridiculously fast, tuples do but are like lists in that you can’t change them directly

Question 13

Things to remember about sets

Answer 13

Don't have an order
best time (better than linear)
can't have more than one of a type of thing in them