Python dict Built-in methods

Python dictionaries have several built-in methods that allow you to perform various operations on them. Here is a list of commonly used dictionary methods:

clear(): Removes all items from the dictionary.

my_dict = {'a': 1, 'b': 2, 'c': 3}
my_dict.clear()
print(my_dict)  # Output: {}

copy(): Returns a shallow copy of the dictionary.

original = {'a': 1, 'b': 2, 'c': 3}
copied = original.copy()
print(copied)  # Output: {'a': 1, 'b': 2, 'c': 3}

get(key, default=None): Returns the value for the specified key if it exists, otherwise returns the default value.
```
my_dict = {'a': 1, 'b': 2, 'c': 3}
value = my_dict.get('d', 'default')
print(value)  # Output: 'default'
```
items(): Returns a view object displaying a list of the dictionary's key-value pairs as tuples.
```
my_dict = {'a': 1, 'b': 2, 'c': 3}
for key, value in my_dict.items():
    print(key, value)
```

keys(): Returns a view object displaying a list of the dictionary's keys.

my_dict = {'a': 1, 'b': 2, 'c': 3}
for key in my_dict.keys():
    print(key)

values(): Returns a view object displaying a list of the dictionary's values.

my_dict = {'a': 1, 'b': 2, 'c': 3}
for value in my_dict.values():
    print(value)

pop(key, default=None): Removes and returns the value for the specified key. If the key is not found and a default value is provided, it returns the default value; otherwise, it raises a KeyError.
```
my_dict = {'a': 1, 'b': 2, 'c': 3}
value = my_dict.pop('b')
print(value)  # Output: 2
print(my_dict)  # Output: {'a': 1, 'c': 3}
```
popitem(): Removes and returns an arbitrary key-value pair as a tuple. If the dictionary is empty, it raises a KeyError.
```
my_dict = {'a': 1, 'b': 2, 'c': 3}
key, value = my_dict.popitem()
print(key, value)
```
setdefault(key, default=None): Returns the value for the specified key if it exists, otherwise sets the key to the specified default value and returns the default value.
```
my_dict = {'a': 1, 'b': 2, 'c': 3}
value = my_dict.setdefault('d', 4)
print(value)  # Output: 4
print(my_dict)  # Output: {'a': 1, 'b': 2, 'c': 3, 'd': 4}
```

Common Dictionary Operations in Python:
- Operations include creating, accessing, modifying, and deleting key-value pairs.
```
# Example
my_dict = {'a': 1, 'b': 2, 'c': 3}
```
Python dict keys() Method:
- The keys() method returns a view of all keys in the dictionary.
```
# Example
keys = my_dict.keys()
```
values() and items() Methods in Python Dictionaries:
- The values() method returns a view of all values, and items() returns key-value pairs.
```
# Example
values = my_dict.values()
items = my_dict.items()
```
How to Use get() Method with Dictionaries in Python:
- The get() method retrieves the value for a given key, or a default value if the key is not present.
```
# Example
value = my_dict.get('a', 'Key not found')
```

Updating and Modifying Dictionaries in Python:

Use assignment to update or add key-value pairs.

# Example
my_dict['d'] = 4  # Add a new key-value pair
my_dict['a'] = 10  # Update an existing value

Python Dictionary pop() and popitem() Methods:
- The pop() method removes and returns the value for a given key.
- The popitem() method removes and returns the last key-value pair.
```
# Example
popped_value = my_dict.pop('b')
popped_item = my_dict.popitem()
```
Dictionary Comprehension vs dict Methods in Python:
- Dictionary comprehension is a concise way to create dictionaries.
- Dict methods (keys(), values(), items()) provide dynamic views on dictionary contents.
```
# Example
squared_dict_comp = {key: value**2 for key, value in my_dict.items()}
squared_dict_method = dict((key, value**2) for key, value in my_dict.items())
```