Dictionary and Tuples Flashcards
What is the syntax for creating a tuple?
my_tuple = (1, 2, 3).
How to create a single-element tuple?
Add a trailing comma: my_tuple = ('item',).
What is the key difference between a list and a tuple?
Tuples are immutable; lists are mutable.
How to access an element in a tuple?
Use indexing: my_tuple[0] (e.g., (1,2,3)[1] → 2).
How to slice a tuple?
Use slicing: my_tuple[start:end:step] (e.g., (1,2,3,4)[1:3] → (2,3)).
What method counts occurrences of a value in a tuple?
.count(value) (e.g., (1,2,2).count(2) → 2).
What method returns the index of a value in a tuple?
.index(value) (e.g., (1,2,3).index(2) → 1).
How to concatenate two tuples?
Use + (e.g., (1,2) + (3,4) → (1,2,3,4)).
How to repeat a tuple?
Use * (e.g., (1,2) * 2 → (1,2,1,2)).
How to convert a list to a tuple?
Use tuple(): tuple([1,2,3]) → (1,2,3).
How to unpack a tuple?
Assign to variables: a, b = (1, 2) → a=1, b=2.
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What is the syntax for creating a dictionary?
my_dict = {'key': 'value'}.
How to access a value in a dictionary?
Use the key: my_dict['key'] (e.g., {'a':1}['a'] → 1).
How to add or update a key-value pair?
Assign directly: my_dict['new_key'] = 'new_value'.
How to safely access a value without raising KeyError?
Use .get(key) (e.g., my_dict.get('key') → value or None).
What method removes a key and returns its value?
.pop(key) (e.g., {'a':1}.pop('a') → 1).
How to remove all items from a dictionary?
Use .clear(): my_dict.clear() → {}.
What method returns all keys in a dictionary?
.keys() (e.g., {'a':1}.keys() → ['a']).
What method returns all values in a dictionary?
.values() (e.g., {'a':1}.values() → [1]).
What method returns key-value pairs as tuples?
.items() (e.g., {'a':1}.items() → [('a',1)]).
How to check if a key exists in a dictionary?
Use in: 'key' in my_dict → True or False.
How to merge two dictionaries?
Use .update(): {'a':1}.update({'b':2}) → {'a':1,'b':2}.
How to create a dictionary from two lists?
Use zip(): dict(zip(keys, values)) (e.g., dict(zip(['a'],[1])) → {'a':1}).
How to create a dictionary with default values?
Use defaultdict from collections or .setdefault().
What is dictionary comprehension?
{k: v for k, v in iterable} (e.g., {x: x*2 for x in range(3)} → {0:0,1:2,2:4}).
How to copy a dictionary?
Use .copy(): new_dict = my_dict.copy().
