python: shorthand notes on Python features from AOC

Programming_Languages/Python/python_advent_learnings.md

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+# Python advent learnings
+
+### Construct paths without hard-coding absolute path
+
+```py
+puzzle_input_path = os.path.join(os.path.dirname(__file__), "data/test_input.txt")
+
+```
+
+### Read file by line and store in variable
+
+```py
+puzzle_input_path = os.path.join(os.path.dirname(__file__), "data/test_input.txt")
+
+def getPuzzleInput(file_path):
+    with open(file_path, "r") as file:
+        return [line.strip() for line in file]
+
+
+puzzle_input = getPuzzleInput(puzzle_input_path)
+
+```
+
+### Conditional tests for members of arrays
+
+Check that all elements are greater than zero:
+
+```py
+if all(element >= 0 for element in array):
+    print('All elements greater than 0')
+```
+
+Check if any element is less than 0:
+
+```py
+if any(element < 0 for element in array):
+    print('There is an element that is less than 0')
+```
+
+### Check for substring:
+
+```py
+text = "latest test"
+if "test" in text:
+    return True
+```
+
+### Control flow in loop
+
+```py
+for counter_values in games:
+    colour = counter_values[1]
+    count = int(counter_values[0])
+    if colour in initial_values.keys() and count > initial_values[colour]:
+        break
+else:
+    valid_games_count += game_number
+```
+
+The use of the `else` clause here is a special feature of Python. The `else` clause after a `for` loop will normally only execute when the loop has finished iterating over the list, but not when the loop is terminated by a `break` statement.
+
+The `else` clause is executed if the `for` loop completes normally. If the `break` statement is executed (i.e., if any count in `counter_values` is greater than the corresponding count in `initial_values`), the `for` loop is terminated and the `else` clause is skipped.
+
+Here the combination of a `for` loop and the `break` statement creates `if, else` logic. If the break condition is not reached, then the `else` block runs for every iteration of the loop.