Iteration

.spellcheck_exceptions_dictionary.txt

@@ -94,6 +94,13 @@ piNY
 psf
 tzYhv
 https
+dev
+lmCu
+ro
+wz
+iter
+tp
+typeobj
 
 
 # pythons implementations:

README.md

@@ -7,6 +7,8 @@
 - An in-depth study of Python's:
   - Interpreter.
     - This focuses on [CPython](https://github.com/python/cpython).
+    - [Annotations on the actual interpreter implementation](https://github.com/praisetompane/python_implementation_study_cpython)
+      - They are prefixed with "Praise:"
   - Python's design, implementation and ecosystem.
 
 ## Language Details
@@ -24,27 +26,30 @@
   - structuring projects:
 - [package index](https://pypi.org)
 - [extending and embedding](https://docs.python.org/3.11/extending/index.html)
+  - [PEP Index](https://www.python.org/dev/peps/)
 - [developer contribution guide](https://devguide.python.org/)
 - memory model:
   - [computational complexity cost model](https://ocw.mit.edu/courses/6-006-introduction-to-algorithms-fall-2011/pages/readings/python-cost-model/)
 - history:
   - [The Story of Python, by Its Creator, Guido van Rossum](https://www.youtube.com/watch?v=J0Aq44Pze-w)
 
-## Testing
-  - [pytest](https://docs.pytest.org/en/latest/index.html#)
+## Community
+- [Discord](https://discuss.python.org)
 
 ## Use Cases
   - [Applications of Python](https://www.python.org/about/apps/)
 
 ## Learning Resources
   - [roadmap](https://roadmap.sh/python)
   - [practice problems](https://www.hackerrank.com/domains/python?filters%5Bstatus%5D%5B%5D=unsolved&badge_type=python)
+  - [What Does It Take To Be An Expert At Python?](https://www.youtube.com/watch?v=7lmCu8wz8ro)
 
 ## Spell Check
 ```shell
 pyspelling -c spellcheck.yaml
 ```
 
+
 # References:
 
 ## Legend:

src/applications/standard_library/3_built_in_types/4_iterator_types/fibonacci.py

@@ -0,0 +1,13 @@
+def fibonacci():
+    a = 0
+    b = 1
+    while True:
+        yield a
+        a = b
+        b = a + b
+
+
+for n in fibonacci():
+    if n > 50:
+        break
+    print(n)

src/applications/standard_library/3_built_in_types/4_iterator_types/remote_control.py

@@ -0,0 +1,23 @@
+class RemoteControlIterator:
+    def __init__(self):
+        self.channels = ['HBO', 'SABC2', 'MNET', 'ESPN']
+        self.current_channel = -1
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        self.current_channel += 1
+        if self.current_channel == len(self.channels):
+            raise StopIteration
+
+        return self.channels[self.current_channel]
+
+
+if __name__ == "__main__":
+    r = RemoteControlIterator()
+
+    try:
+       print(f"Channel {next(r)}")
+    except StopIteration:
+       print("All Channel Explored. Goodbye")

standard_library/3_built_in_types/4_iterator_types/0_iterators.py

@@ -0,0 +1,70 @@
+"""
+  def iterator:
+    - formal:
+      - in words: an object that represents a stream of data.
+
+    - properties:
+      - forward and reserve traversal.
+      - can only be traversed once.
+    - plain english: ???
+
+    - intuition: ???
+
+    - properties: ???
+
+    - examples: ???
+
+    - use cases: ???
+
+    - proof: None. It is a definition.
+
+  References:
+    PEP 234 – Iterators. https://peps.python.org/pep-0234/
+"""
+
+collection = [i for i in range(5)]
+
+print("Forward Iteration with next(forward_iterator)")
+forward_iterator = iter(collection)
+print(f"Type: {type(forward_iterator)}")
+print(f"Print next element {next(forward_iterator)}")
+print(f"Print next element {next(forward_iterator)}")
+print(f"Print next element {next(forward_iterator)}")
+print(f"Print next element {next(forward_iterator)}")
+print(f"Print next element {next(forward_iterator)}")
+# print(f"Print next element {next(forward_iterator)}")
+print("\n")
+
+print("Forward Iteration with __next__")
+forward_iterator_2 = iter(collection)
+print(f"Print next element {forward_iterator_2.__next__()}")
+print(f"Print next element {forward_iterator_2.__next__()}")
+print(f"Print next element {forward_iterator_2.__next__()}")
+print(f"Print next element {forward_iterator_2.__next__()}")
+print(f"Print next element {forward_iterator_2.__next__()}")
+# print(f"Print next element {forward_iterator)}")
+print("\n")
+
+print("Reverse Iteration")
+reverse_iterator = reversed(collection)
+print(f"Type: {type(forward_iterator)}")
+print(f"Print next element {next(reverse_iterator)}")
+print(f"Print next element {next(reverse_iterator)}")
+print(f"Print next element {next(reverse_iterator)}")
+print(f"Print next element {next(reverse_iterator)}")
+print(f"Print next element {next(reverse_iterator)}")
+# print(f"Print next element {next(reverse_iterator)}")
+print("\n")
+
+# Single Travel Example
+collection = [i for i in range(5)]
+iterator = iter(collection)
+
+print("First pass of the iterator")
+for v in iterator:
+    print(v)
+
+# This next pass will fail, because we have exhausted the iterator's single pass
+print("Second pass of the iterator")
+for v in iterator:
+    print(v)

standard_library/3_built_in_types/4_iterator_types/1_generators.py

@@ -0,0 +1,43 @@
+"""    
+  def generator | generator function: 
+    - formal: 𝑓: any ↦ Generator Iterator
+        - in words: a function that creates and returns a Generator Iterator.
+
+    - plain english: ???
+
+    - intuition: ???
+
+    - properties: ???
+
+    - examples:
+      - useful example: src/applications/math/fibonacci.py
+
+    - use cases: ???
+
+    - proof: None. It is a definition.
+
+  References:
+    PEP 255 – Simple Generators. https://www.python.org/dev/peps/pep-0255/#motivation
+
+"""
+
+
+def generate_infinite_numbers():
+    """
+    Generate infinite numbers
+    """
+    number = 0
+    while True:
+        yield number
+        number += 1
+
+
+def generator_expression():
+    sum(i * i for i in range(10))
+
+
+if __name__ == "__main__":
+    for number in generate_infinite_numbers():
+        print(number)
+
+    # print(generator_expression())