Notes in Python fundamentals

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☝️ What does the deck cover? Python fundamentals, from print("hello world") up, including:

- core language features, e.g. data types, dunder methods, mutability and assignment, scope, generators, decorators, context managers, inheritance, pattern matching, ...

- key parts of the standard library, e.g. regular expressions, type hints, the debugger, itertools, functools, abstract base classes, path manipulation, concurrency...

It starts simple but gets advanced. The deck helped me learn Python fast, and I continue to use it daily as a professional Python programmer.

✏️ How to use? You can't learn programming through Anki alone. But Anki can vastly speed up your learning, used alongside other resources. If you're newish to Python, try reviewing the cards in order of date created, because later cards build on earlier ones. If you're comfortable with Python, try searching for a topic of interest (say, set or generator). Notes about the standard library's module foobar are tagged python_foobar.

Status	Last Update	Fields
Published	07/10/2024	def f(): x = 1 x = 2 f() print(x)
Published	07/10/2024	def func(): global x x = 1 x = 2 func() print(x)
Published	07/10/2024	def func(): def nested(): global x x = 1 nested() x = 2 func() print(x)
Published	07/10/2024	def func(): def nested(): nonlocal x x = 1 x = 3 nested() print("func:", x) x = 2 func() print("global:", x) …
Published	07/10/2024	def func(): def nested(): def nested2(): nonlocal x x = 100 print("nested2:", x) x = 50 neste…
Published	07/10/2024	Python. A {{c1::docstring}} is {{c2::a string literal which is the first expression in a class, function or module}} and is automatically stored in it…
Published	07/10/2024	def func(): print('first') func() def func(): print('second') func()
Published	07/10/2024	for i in range(3): print(i) if i == 1: break else: print('end')
Published	07/10/2024	print("foo", "bar", sep="baz", end="qux")
Published	07/10/2024	get my_string's length
Published	07/10/2024	create a string object from obj
Published	07/10/2024	convert my_string to upper case, returning a new string
Published	07/10/2024	text = "ababab" print(text.replace("a", "c"))
Published	07/10/2024	replace the first two occurrences of "foo" in my_string by "bar", returning a new string
Published	07/10/2024	def func(): global x x = 1 func() print(x)
Published	07/10/2024	lst = ["a", "b", "c", "d", "e"] print(lst[0], lst[-1])
Published	07/10/2024	my_list = ['a', 'b', 'c', 'd', 'e'] print(my_list[1:4])
Published	07/10/2024	text = "foo bar foo bar" print(text.find("bar"))
Published	07/10/2024	get the index of the first occurrence of "foo" in my_string, starting from index 5
Published	07/10/2024	get the index of the first occurrence of "foo" in my_string, between index 10 and 20
Published	07/10/2024	text = "abababab" i = text.count("abab") print(i)
Published	07/10/2024	get the number of non-overlapping occurrences of "foo" in my_string, between indexes 5 and 13
Published	07/10/2024	t = 'AaBbCcDd' print(t[::2]) print(t[1::2])
Published	07/10/2024	t = "12345" print(t[::-1]) print(t[::-2])
Published	07/10/2024	t = "12345" print(t[1:-1])
Published	07/10/2024	print(5 // 2)
Published	07/10/2024	print(-5 // 2)
Published	07/10/2024	print(5 % 2)
Published	07/10/2024	t = (1, 2) t[1] = 3
Published	07/10/2024	s = "hello" s[1] = "u"
Published	07/10/2024	a = 1 b = a print(a is b) b = 2 print(a is b)
Published	07/10/2024	a = [1, 2] b = a print(a is b) b[0] = 3 print(a is b) print(a, b)
Published	07/10/2024	a = [1, 2] b = a print(a is b) b = 3 print(a is b) print(a, b)
Published	07/10/2024	a = [1, 2] b = a[:] print(a is b) print(a, b)
Published	07/10/2024	a = [1] b = [0, a] print(b) print(a in b) b[1] = 'test' print(b) print(a in b)
Published	07/10/2024	a = [1] b = [0, a] print(a, b) print(a in b) b[1][0] = "test" print(a, b) print(a in b) print(a is b[1])
Published	07/10/2024	a = [1] b = [a] c = [b] print(a in b) print(a in c) print(a in c[0])
Published	07/10/2024	text = "hello world" print("world" in text)
Published	07/10/2024	import copy a = [1] b = [0, a] c = copy.copy(b) print(c is b) print(c[1] is b[1]) print(b[1] is a)
Published	07/10/2024	print("foo" "bar")
Published	07/10/2024	text = " I met a traveller " words = text.split() print(words)
Published	07/10/2024	text = "a b c d" words = text.split(None, 2) print(words)
Published	07/10/2024	text = "ABBA"words = text.split("B")print(words)
Published	07/10/2024	t = "hel lo"print(list(t))
Published	07/10/2024	def func(): passprint(func())
Published	07/10/2024	x = [0, 1, 2, 3] x[1] = [] print(x)
Published	07/10/2024	x = [0, 1, 2, 3] x[1:2] = [] print(x)
Published	07/10/2024	x = [0, 1, 2, 3]x[1:3] = []print(x)
Published	07/10/2024	x = [0, 1, 2, 3] x[::2] = [] print(x)
Published	07/10/2024	x = [0, 1, 2, 3] x[::2] = [7, 8] print(x)
Published	07/10/2024	x = [0, 1, 2, 3] y = x.pop() print(x) print(y)
Published	07/10/2024	x = [0, 10, 20, 30] y = x.pop(1) print(x) print(y)
Published	07/10/2024	x = [4, 5, 6, 5] x.remove(5) print(x)
Published	07/10/2024	x = [0, 1, 2, 3]x.remove(4)print(x)
Published	07/10/2024	x = [0, 1, 2] x.append(3) print(x)
Published	07/10/2024	x = [0, 1, 2] x.append([3 ,4]) print(x) print(x[3])
Published	07/10/2024	x = [0, 1, 2] x.extend([3, 4]) print(x)
Published	07/10/2024	x = [0, 1, 2] x.extend(3) print(x)
Published	07/10/2024	for i in range(5): if i == 2: continue print(i, end=" ")
Published	07/10/2024	x = () print(type(x)) x = (1) print(type(x)) x = (1,) print(type(x))
Published	07/10/2024	data = {"a": 1, "b": 2, "c": 3} print(data["a"])
Published	07/10/2024	data = {"a": 1, "a": 2, "c": 3} print(data["a"])
Published	07/10/2024	data = {'a': 1, 'b': 2, 'c': 3} data['a'] = 4 print(data)
Published	07/10/2024	data = {"a": 1, "b": 2} data["c"] = 3 print(data)
Published	07/10/2024	data = {"a": 1, "b": 2}data[66] = 77print(data)
Published	07/10/2024	data = {x: "abc"[x] for x in range(3)} print(data)
Published	07/10/2024	if condition: x = 1 else: x = 2
Published	07/10/2024	seq = ["a", "b", "c"] x = "-".join(seq) print(x)
Published	07/10/2024	x = 2 y = 3 print(1 < x < y < 4)
Published	07/10/2024	x = (i**2 for i in range(4))print(x)
Published	07/10/2024	x = tuple(i**2 for i in range(4)) print(x)
Published	07/10/2024	x = [0, 1] print(x[2])
Published	07/10/2024	x = {"a": 0, "b": 1} print(x["c"])
Published	07/10/2024	a, b, c = [1, 2, 3, 4, 5] print(a, b, c)
Published	07/10/2024	a, b, *c = [1, 2, 3, 4, 5] print(a, b, c)
Published	07/10/2024	*a, b, c = [1, 2, 3, 4, 5] print(a, b, c)
Published	07/10/2024	a, *b, c = [1, 2, 3, 4, 5]print(a, b, c)
Published	07/10/2024	a, b, c = [1, 2, 3, 4, 5] print(a, b, c)
Published	07/10/2024	x = [4, 5, 6, 7] print(x) print(*x)
Published	07/10/2024	text = "foo bar baz "x = text.rsplit()print(x)
Published	07/10/2024	foo = lambda x: x+1 bar = foo(1) print(bar)
Published	07/10/2024	foo = lambda x: x+1 print(type(foo))
Published	07/10/2024	func = lambda: 1 if x else 2 x = True print(func()) x = False print(func())
Published	07/10/2024	def func(x=[]): x.append(1) return x for i in range(4): print(func())
Published	07/10/2024	def func(x=[1], y=[99]): x[0], y[0] = y[0], x[0] print(x, y) for i in range(4): func()
Published	07/10/2024	def func(x): return x print("here") print(func(1))
Published	07/10/2024	x = [[0]]*3 print(x) x[2][0] = 1 print(x) print(x[1] is x[2])
Published	07/10/2024	x = (0,) * 3 print(x) y = [1] * 3 print(y)
Published	07/10/2024	x = 1, 2 print(type(x))
Published	07/10/2024	x, *y = 1, 2, 3 print(type(x)) print(type(y))
Published	07/10/2024	x = ['a', 'b', 'c', 'd']for a, b in enumerate(x): print(a, b)
Published	07/10/2024	yield (index, item) pairs from my_stream, counting from 5
Published	07/10/2024	def out(): def inn(): nonlocal x x = 5 inn() out()
Published	07/10/2024	def out(): global x x = 5out()print(x)
Published	07/10/2024	x = ([],) x[0] = 1 print(x)
Published	07/10/2024	x = [] x[0] = 999 print(x)
Published	07/10/2024	x = ([],) x[0].append("a") x[0].append("b") print(x)
Published	07/10/2024	x = {'a': 1, 'b': 2} y = {'b': 3, 'c': 4} x.update(y) print(x)
Published	07/10/2024	for collection in [[], (), {}, [1], (1,), {"a": 1}]: print(bool(collection), end=" ")
Published	07/10/2024	x = 1 or 3 print(x) x = 1 and 3 print(x)
Published	07/10/2024	x = 0 or 3 print(x) x = 0 and 3 print(x)
Published	07/10/2024	def foo(): print("here") return False x = foo() and False print(x) y = False and foo() print(y)
Published	07/10/2024	def foo(): print("here") return False x = foo() or True print(x) y = True or foo() print(y)
Published	07/10/2024	def foo(): print("here") return 1 x = [foo(), foo(), foo()] print('x:', x)
Published	07/10/2024	def foo(): global y y += 1 y = 0 x = (foo() for i in range(3)) print(y) next(x) print(y)
Published	07/10/2024	x = not "bloop" print(x)
Published	07/10/2024	y = [bool(i) for i in ("", "0", "None", "False")] print(*y)
Published	07/10/2024	func = lambda x=1, y=1: x + yprint(func())print(func(2))print(func(2, 3))
Published	07/10/2024	x = [0, 0, 1, 0, 1] if any(x): print("yes") else: print("no")
Published	07/10/2024	x = [0, "", 0.0, False]if any(x): print("yes")else: print("no")
Published	07/10/2024	x = [1, 2, 3] if all(x): print("yes") else: print("no")
Published	07/10/2024	def func(): yield 1 yield 2 yield 3 print(type(func)) print(type(func()))
Published	07/10/2024	def func(): output = 0 while True: new = yield output output = new genr = func() print(next(genr)) print(next(genr)) print(ne…
Published	07/10/2024	def func(): output = 0 while True: new = yield output output = new genr = func() print(next(genr)) print(next(genr)) print(ge…
Published	07/10/2024	def func(): output = 0 while True: new = yield output output = new if new is not None else output genr = func() print(next(g…
Published	07/10/2024	def func(): output = 0 while True: new = yield output output = new if new is not None else output genr = func() print(genr.s…
Published	07/10/2024	class MyClass: pass MyClass.x = 1 print(MyClass.x)
Published	07/10/2024	text = "abcabcabc" y = "".join( [ char.upper() for char in text if char != "a" ] ) print(y)
Published	07/10/2024	def func(): pass func.x = 5 print(func.x)
Published	07/10/2024	def func(): print("here") return func func()()()
Published	07/10/2024	text = "Hello world" x = text.lower()[::-1].title() print(x)
Published	07/10/2024	class Foo: x = 1 foo = Foo() print(foo.x)
Published	07/10/2024	a = [1, 2, 3] b = [4, 5, 6] for i in zip(a, b): print(i)
Published	07/10/2024	a = [1, 2] b = [3, 4, 5] for i in zip(a, b): print(i)
Published	07/10/2024	a = "hello" b = "world" print(*zip(a, b)), sep='\n')
Published	07/10/2024	strings = ["a", "ab", "abc", "abcd", "abcde"] for string in strings: print(string.rjust(4, "_"))
Published	07/10/2024	strings = ["a", "aa", "aaa", "aaaa", "aaaaa"] for string in strings: print(string.center(6, "_"))
Published	07/10/2024	def wrap(func): return 1 @wrap def foo(): return 2 print(foo, type(foo))
Published	07/10/2024	def wrap(func): def wrapped(arg): return func(arg) + 1 return wrapped @wrap def foo(x): return x print(foo(1))
Published	07/10/2024	def wrap(func): def wrapped(y=2): return func(y) return wrapped @wrap def foo(x=1): return x print(foo())
Published	07/10/2024	x = [ ['a','a','a'], ['b','b','b'], ['c','c','c'], ] y = zip(*x) print(list(y))
Published	07/10/2024	a = [1, 2, 3] b = a c = [5, 6] a += c print(a, b, c, sep='\n')
Published	07/10/2024	a = [1, 2, 3] b = a c = [5, 6] a = a + c print(a, b, c, sep='\n')
Published	07/10/2024	x = {1, 2, 3} y = {2, 3, 4} print(x \| y)
Published	07/10/2024	x = {1, 2, 3} y = {2, 3, 4} print(x & y)
Published	07/10/2024	x = {1, 2, 3} y = {2, 3, 4} print(x - y) print(y - x)
Published	07/10/2024	x = {1, 2, 3} y = {2, 3, 4} print(x ^ y)
Published	07/10/2024	x = {1, 2, 3}y = {}print(x & y)
Published	07/10/2024	x = {1, 2, 3} y = set() print(x & y)
Published	07/10/2024	x = ["when", "a", "knight", "won", "his", "spurs"] x.sort() print(x)
Published	07/10/2024	x = ["a", "b", 2, 1] x.sort() print(x)
Published	07/10/2024	x = ["a", "b", 2, 1] x.sort(key=str) print(x)
Published	07/10/2024	sort list_of_strings in place by the last character
Published	07/10/2024	x = {char.lower() for char in "Foo Bar" if char} print(x) print(type(x))
Published	07/10/2024	class Thing(): def __init__(self): self.x = 0 def __call__(self, arg): self.x = arg print(self.x) thing = Thing() pr…
Published	07/10/2024	class Foo: def __init__(self, x, y): self.x = x self.y = y def px(self): print(self.x) return self def py(self): …
Published	07/10/2024	def foo(func, x): return func(x) print(foo(lambda x: x * 3, 8)
Published	07/10/2024	words = ['abc', 'def', 'ghi'] t = [''.join(chars) for chars in zip(*words)] print(t)
Published	07/10/2024	for i in range(1, 3): print(i) print(i)
Published	07/10/2024	x = [1, 2, 3] y = x.reverse() print(x) print(y)
Published	07/10/2024	print(True + True) print(True * 3 + True / 2) print(5 * False) print(10 ** False)
Published	07/10/2024	print(True / False)
Published	07/10/2024	from functools import reduce foo = reduce(lambda x, y: x + y, [1, 2, 3, 4]) print(foo)
Published	07/10/2024	from functools import reduce print(reduce(lambda x, y: x+y, [1]))
Published	07/10/2024	from functools import reduce print(reduce(lambda x, y: x+y, [1], 9))
Published	07/10/2024	Python. Give some examples of built-in sequences.
Published	07/10/2024	x, y = [1, 2]print(x, y)
Published	07/10/2024	x, y = 'hi' print(x, y)
Published	07/10/2024	mdy = "OCT/04/1992" date = mdy.split("/") dmy = f"{date[1]}/{date[0]}/{date[2]}"
Published	07/10/2024	color, (x, y, z) = "red", (1, 2, 3) print(color, x, y, z)
Published	07/10/2024	start_points = [(1, 1), (2, 5), (-3, -4)] end_points = [(1, -1), (3, 6), (3, -4)] for start, end in zip(start_points, end_points): if start[0] ==…
Published	07/10/2024	name = "Ken Thompson" year = 2020 print(f"{name} turned {year - 1943} in {year}.")
Published	07/10/2024	Python. Give some examples of built-in non-sequence iterables.
Published	07/10/2024	Python. What are iterators?
Published	07/10/2024	Python. Give some examples of iterators.
Published	07/10/2024	matrix = [[1,2], [3,4]]flattened = [ item for row in matrix for item in row]print(flattened)
Published	07/10/2024	Python. List comprehensions are to lists as {{c1::generator expressions}} are to generators.
Published	07/10/2024	def func(*args): print(type(args)) print(args) print(sum(args)) func(1, 2, 3)
Published	07/10/2024	def foo(sequence): return [sequence[1::2], sequence[0::2]] print(foo('0123456'))
Published	07/10/2024	dict1 = {'a': 1, 'b': 2}dict2 = {'b': 3, 'c': 4}dict3 = {dict1, dict2, 'c': 5}print(dict3)
Published	07/10/2024	dict1 = {'a': 1, 'b': 2}dict2 = {'b': 3, 'c': 4}foo = {dict1, dict2}print(foo, type(foo))
Published	07/10/2024	def counter(maximum): i = 0 while i < maximum: val = (yield i) if val is not None: i = val else: …
Published	07/10/2024	def counter(maximum): i = 0 while i < maximum: yield i i += 1 it = counter(3) for _ in range(4): print(next(it))
Published	07/10/2024	def counter(maximum): i = 0 while i < maximum: yield i i += 1 it = counter(3) for _ in range(5): print(next(it, 'exhau…
Published	07/10/2024	def func(): x = 1 def inner_func(): print(x) inner_func() x = 0 func()
Published	07/10/2024	Python. In what order are namespaces searched?
Published	07/10/2024	def foo(): lst = [] for i in range(4): lst.append(lambda: i) print([f() for f in lst]) foo()
Published	07/10/2024	nums = [1, 2, 3, 4, 5] for n in nums: if n % 2 == 0: print(2**n)
Published	07/10/2024	def gen(stream): for n in stream: if n % 2 == 0: return else: yield nnums = [1, 3, 4, 1, 2]for n in gen(nums): …
Published	07/10/2024	x, y = {1: 'a', 2: 'b'} print(x, y)
Published	07/10/2024	def palindromic(sequence): for from_left, from_right in zip(sequence, sequence[::-1]): if from_left != from_right: return Fals…
Published	07/10/2024	print(reversed(x**2 for x in range(4)))
Published	07/10/2024	print(type(sorted((2, 3, 1))))
Published	07/10/2024	def foo(x, *, y): return x + y print(foo(1, 1))
Published	07/10/2024	def foo(x, *, y): return x + yprint(foo(1, y=2))
Published	07/10/2024	def foo(**attributes): print(type(attributes)) return attributes.popitem() print(foo( name='Cosmo', age=29, day='11/25/2020', …
Published	07/10/2024	def func(x, y, z): return (x - y) * z print(func(y=1, z=3, x=2))
Published	07/10/2024	def func(x, y, z): return (x - y) * z print(func(x=1, 0, 2))
Published	07/10/2024	from functools import reduce numbers = [1, 2, 3, 4, 5] product = reduce(lambda x, y: x * y, numbers) print(product)
Published	07/10/2024	w = {1, 2, 3, 4, 5} x = {1, 2, 3} y = {2, 3, 4} print(w - (x & y) == (w - x) \| (w - y))
Published	07/10/2024	w = {1, 2, 3, 4, 5} x, y = (w,) print(x, y)
Published	07/10/2024	dict1 = {'a': 1, 'b': 2} dict2 = {'b': 3, 'c': 4} new = {dict1, dict2} print(type(new)) print(new)
Published	07/10/2024	Python. Why do you need to be cautious when using assert statements?
Published	07/10/2024	assert (1 == 2, 'Failed')
Published	07/10/2024	my_list = ['long_item', 'another_long_item', 'yet_another_long_item']
Published	07/10/2024	f = open("my_file.txt", 'w') f.write("blah blah") f.close()
Published	07/10/2024	foo = (3, 1, 4, 2) bar = sorted(foo) print(type(bar))
Published	07/10/2024	foo = (3, 1, 4, 2) bar = reversed(foo) print(type(bar))
Published	07/10/2024	Python. A {{c1::single leading underscore}} in a name conventionally indicates that {{c2::the name is private}}.
Published	07/10/2024	Python. To avoid a name shadowing a built-in, the convention is {{c1::to add a trailing underscore}}.
Status	Last Update	Fields