updated contents from Atlas repo

iterables/CACM/citation.txt

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+Examples in this directory were adapted from:
+
+Erik Meijer. 2014. The curse of the excluded middle.
+Commun. ACM 57, 6 (June 2014), 50-55. DOI=10.1145/2605176
+http://doi.acm.org/10.1145/2605176

iterables/CACM/closed_file.py

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+"""
+Erik Meijer. 2014. The curse of the excluded middle.
+Commun. ACM 57, 6 (June 2014), 50-55. DOI=10.1145/2605176
+http://doi.acm.org/10.1145/2605176
+"""
+
+with open('citation.txt', encoding='ascii') as fp:
+    get_contents = lambda: fp.read()
+
+print(get_contents())

iterables/CACM/haha.py

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+"""
+Erik Meijer. 2014. The curse of the excluded middle.
+Commun. ACM 57, 6 (June 2014), 50-55. DOI=10.1145/2605176
+http://doi.acm.org/10.1145/2605176
+"""
+
+def ha():
+    ha = 'Ha'
+    print(ha)
+    return ha
+
+# prints 'Ha' twice before showing result
+print('result ->', ha() + ha())
+
+# prints 'Ha' only once before showing reult
+ha_res = ha()  # common subexpression elimination
+print('result ->', ha_res + ha_res)

iterables/CACM/less_more.py

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+"""
+Meijer, Erik - The Curse of the Excluded Middle
+DOI:10.1145/2605176
+CACM vol.57 no.06
+"""
+
+def less_than_30(n):
+    check = n < 30
+    print('%d < 30 : %s' % (n, check))
+    return check
+
+def more_than_20(n):
+    check = n > 20
+    print('%d > 20 : %s' % (n, check))
+    return check
+
+l = [1, 25, 40, 5, 23]
+q0 = (n for n in l if less_than_30(n))
+q1 = (n for n in q0 if more_than_20(n))
+
+for n in q1:
+    print('-> %d' % n)

iterables/CACM/zero_div.py

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+"""
+Erik Meijer. 2014. The curse of the excluded middle.
+Commun. ACM 57, 6 (June 2014), 50-55. DOI=10.1145/2605176
+http://doi.acm.org/10.1145/2605176
+"""
+
+l = range(10, -1, -1)
+try:
+    res = (1/x for x in l)
+except ZeroDivisionError:
+    res = []
+
+for z in res:
+    print(z)

iterables/sentence_gen.doctest

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+>>> from sentence_gen import Sentence
+>>> s = Sentence('The time has come')
+>>> s
+Sentence('The time has come')
+>>> list(s)
+['The', 'time', 'has', 'come']
+>>> it = iter(s)
+>>> next(it)
+'The'
+>>> next(it)
+'time'
+>>> next(it)
+'has'
+>>> next(it)
+'come'
+>>> next(it)
+Traceback (most recent call last):
+  ...
+StopIteration
+
+>>> s = Sentence('"The time has come," the Walrus said,')
+>>> s
+Sentence('"The time ha... Walrus said,')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said']
+
+
+>>> s = Sentence('''"The time has come," the Walrus said,
+... "To talk of many things:"''')
+>>> s
+Sentence('"The time ha...many things:"')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said', 'To', 'talk', 'of', 'many', 'things']
+
+
+>>> s = Sentence('Agora vou-me. Ou me vão?')
+>>> s
+Sentence('Agora vou-me. Ou me vão?')
+>>> list(s)
+['Agora', 'vou', 'me', 'Ou', 'me', 'vão']

iterables/sentence_gen.py

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+"""
+Sentence: iterate over words using a generator function
+"""
+
+import re
+import reprlib
+
+RE_WORD = re.compile('\w+')
+
+
+class Sentence:
+
+    def __init__(self, text):
+        self.text = text
+
+    def __repr__(self):
+        return 'Sentence(%s)' % reprlib.repr(self.text)
+
+    def __iter__(self):
+        for match in RE_WORD.finditer(self.text):  # <1>
+            yield match.group()  # <2>
+
+# done! <3>

iterables/sentence_genexp.doctest

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+>>> from sentence_genexp import Sentence
+>>> s = Sentence('The time has come')
+>>> s
+Sentence('The time has come')
+>>> list(s)
+['The', 'time', 'has', 'come']
+>>> it = iter(s)
+>>> next(it)
+'The'
+>>> next(it)
+'time'
+>>> next(it)
+'has'
+>>> next(it)
+'come'
+>>> next(it)
+Traceback (most recent call last):
+  ...
+StopIteration
+
+>>> s = Sentence('"The time has come," the Walrus said,')
+>>> s
+Sentence('"The time ha... Walrus said,')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said']
+
+
+>>> s = Sentence('''"The time has come," the Walrus said,
+... "To talk of many things:"''')
+>>> s
+Sentence('"The time ha...many things:"')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said', 'To', 'talk', 'of', 'many', 'things']
+
+
+>>> s = Sentence('Agora vou-me. Ou me vão?')
+>>> s
+Sentence('Agora vou-me. Ou me vão?')
+>>> list(s)
+['Agora', 'vou', 'me', 'Ou', 'me', 'vão']

iterables/sentence_genexp.py

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+"""
+Sentence: iterate over words using a generator expression
+"""
+
+# BEGIN SENTENCE_GENEXP
+import re
+import reprlib
+
+RE_WORD = re.compile('\w+')
+
+
+class Sentence:
+
+    def __init__(self, text):
+        self.text = text
+
+    def __repr__(self):
+        return 'Sentence(%s)' % reprlib.repr(self.text)
+
+    def __iter__(self):
+        return (match.group() for match in RE_WORD.finditer(self.text))
+# END SENTENCE_GENEXP
+
+
+def main():
+    import sys
+    import warnings
+    try:
+        filename = sys.argv[1]
+        word_number = int(sys.argv[2])
+    except (IndexError, ValueError):
+        print('Usage: %s <file-name> <word-number>' % sys.argv[0])
+        sys.exit(1)
+    with open(filename, 'rt', encoding='utf-8') as text_file:
+        s = Sentence(text_file.read())
+    for n, word in enumerate(s, 1):
+        if n == word_number:
+            print(word)
+            break
+    else:
+        warnings.warn('last word is #%d, "%s"' % (n, word))
+
+if __name__ == '__main__':
+    main()

iterables/sentence_iter.doctest

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+>>> from sentence_iter import Sentence
+>>> s = Sentence('The time has come')
+>>> s
+Sentence('The time has come')
+>>> list(s)
+['The', 'time', 'has', 'come']
+>>> it = iter(s)
+>>> next(it)
+'The'
+>>> next(it)
+'time'
+>>> next(it)
+'has'
+>>> next(it)
+'come'
+>>> next(it)
+Traceback (most recent call last):
+  ...
+StopIteration
+
+>>> s = Sentence('"The time has come," the Walrus said,')
+>>> s
+Sentence('"The time ha... Walrus said,')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said']
+
+
+>>> s = Sentence('''"The time has come," the Walrus said,
+... "To talk of many things:"''')
+>>> s
+Sentence('"The time ha...many things:"')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said', 'To', 'talk', 'of', 'many', 'things']
+
+
+>>> s = Sentence('Agora vou-me. Ou me vão?')
+>>> s
+Sentence('Agora vou-me. Ou me vão?')
+>>> list(s)
+['Agora', 'vou', 'me', 'Ou', 'me', 'vão']

iterables/sentence_iter.py

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+"""
+Sentence: iterate over words using the Iterator Pattern, take #1
+
+WARNING: the Iterator Pattern is much simpler in idiomatic Python;
+see: sentence_gen*.py.
+"""
+
+# BEGIN SENTENCE_ITER
+import re
+import reprlib
+
+RE_WORD = re.compile('\w+')
+
+
+class Sentence:
+
+    def __init__(self, text):
+        self.text = text
+        self.words = RE_WORD.findall(text)
+
+    def __repr__(self):
+        return 'Sentence(%s)' % reprlib.repr(self.text)
+
+    def __iter__(self):  # <1>
+        return SentenceIter(self.words)  # <2>
+
+
+class SentenceIter:
+
+    def __init__(self, words):
+        self.words = words  # <3>
+        self.index = 0  # <4>
+
+    def __next__(self):
+        try:
+            word = self.words[self.index]  # <5>
+        except IndexError:
+            raise StopIteration()  # <6>
+        self.index += 1  # <7>
+        return word  # <8>
+
+    def __iter__(self):  # <9>
+        return self
+# END SENTENCE_ITER
+
+def main():
+    import sys
+    import warnings
+    try:
+        filename = sys.argv[1]
+        word_number = int(sys.argv[2])
+    except (IndexError, ValueError):
+        print('Usage: %s <file-name> <word-number>' % sys.argv[0])
+        sys.exit(1)
+    with open(filename, 'rt', encoding='utf-8') as text_file:
+        s = Sentence(text_file.read())
+    for n, word in enumerate(s, 1):
+        if n == word_number:
+            print(word)
+            break
+    else:
+        warnings.warn('last word is #%d, "%s"' % (n, word))
+
+if __name__ == '__main__':
+    main()

iterables/sentence_iter2.doctest

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+>>> from sentence_iter2 import Sentence
+>>> s = Sentence('The time has come')
+>>> s
+Sentence('The time has come')
+>>> list(s)
+['The', 'time', 'has', 'come']
+>>> it = iter(s)
+>>> next(it)
+'The'
+>>> next(it)
+'time'
+>>> next(it)
+'has'
+>>> next(it)
+'come'
+>>> next(it)
+Traceback (most recent call last):
+  ...
+StopIteration
+
+>>> s = Sentence('"The time has come," the Walrus said,')
+>>> s
+Sentence('"The time ha... Walrus said,')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said']
+
+
+>>> s = Sentence('''"The time has come," the Walrus said,
+... "To talk of many things:"''')
+>>> s
+Sentence('"The time ha...many things:"')
+>>> list(s)
+['The', 'time', 'has', 'come', 'the', 'Walrus', 'said', 'To', 'talk', 'of', 'many', 'things']
+
+
+>>> s = Sentence('Agora vou-me. Ou me vão?')
+>>> s
+Sentence('Agora vou-me. Ou me vão?')
+>>> list(s)
+['Agora', 'vou', 'me', 'Ou', 'me', 'vão']

iterables/sentence_iter2.py

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+"""
+Sentence: iterate over words using the Iterator Pattern, take #2
+
+WARNING: the Iterator Pattern is much simpler in idiomatic Python;
+see: sentence_gen*.py.
+"""
+
+import re
+import reprlib
+
+RE_WORD = re.compile('\w+')
+
+
+class Sentence:
+
+    def __init__(self, text):
+        self.text = text
+
+    def __repr__(self):
+        return 'Sentence(%s)' % reprlib.repr(self.text)
+
+    def __iter__(self):
+        word_iter = RE_WORD.finditer(self.text)  # <1>
+        return SentenceIter(word_iter)  # <2>
+
+
+class SentenceIter():
+
+    def __init__(self, word_iter):
+        self.word_iter = word_iter  # <3>
+
+    def __next__(self):
+        match = next(self.word_iter)  # <4>
+        return match.group()  # <5>
+
+    def __iter__(self):
+        return self

iterables/simplest_generators.doctest

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+>>> def gen_123():
+...     yield 1
+...     yield 2
+...     yield 3
+...
+>>> gen_123  # doctest: +ELLIPSIS
+<function gen_123 at 0x...>
+>>> gen_123()   # doctest: +ELLIPSIS
+<generator object gen_123 at 0x...>
+>>> for i in gen_123():
+...     print(i)
+1
+2
+3
+>>> g = gen_123()
+>>> next(g)
+1
+>>> next(g)
+2
+>>> next(g)
+3
+>>> next(g)
+Traceback (most recent call last):
+  ...
+StopIteration
+
+
+>>> def gen_AB():
+...     print('start')
+...     yield 'A'
+...     print('continue')
+...     yield 'B'
+...     print('end.')
+...
+>>> for c in gen_AB():
+...     print('--->', c)
+...
+start
+---> A
+continue
+---> B
+end.

iterables/vector.py

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+"""
+
+The `+` operator produces a `Vector` result.
+
+    >>> v1 = Vector(2, 4)
+    >>> v2 = Vector(2, 1)
+    >>> v1 + v2
+    Vector(4, 5)
+
+We can also implemement the `*` operator to perform scalar multiplication
+or elementwise multiplication.
+
+    >>> v = Vector(3, 4)
+    >>> abs(v)
+    5.0
+    >>> v * 3
+    Vector(9, 12)
+    >>> abs(v * 3)
+    15.0
+    >>> v25 = Vector(2, 5)
+    >>> v71 = Vector(7, 1)
+    >>> v71 * v25
+    Vector(14, 5)
+
+A vector can be used in a boolean context, where it will be considered
+_falsy_ if it has magnitude zero, otherwise it is _truthy_::
+
+    >>> bool(v)
+    True
+    >>> bool(Vector(0, 0))
+    False
+
+Vectors can have n-dimensions::
+
+    >>> v3 = Vector(1, 2, 3)
+    >>> len(v3)
+    3
+    >>> v3
+    Vector(1, 2, 3)
+    >>> abs(v3)  # doctest:+ELLIPSIS
+    3.74165738...
+    >>> v3 + Vector(4, 5, 6)
+    Vector(5, 7, 9)
+    >>> v3 * 5
+    Vector(5, 10, 15)
+    >>> v2 + v3
+    Traceback (most recent call last):
+      ...
+    ValueError: Addition applies only to vectors of equal dimensions.
+
+The `repr` of a Vector is produced with the help of the `reprlib.repr`
+function, limiting the size of the output string:
+
+    >>> Vector(*range(100))
+    Vector(0, 1, 2, 3, 4, 5, ...)
+
+"""
+
+# BEGIN VECTOR_ITER
+import math
+import numbers
+import reprlib
+
+EQ_DIMENSIONS_MSG = '%s applies only to vectors of equal dimensions.'
+
+class Vector:
+    """An n-dimensional vector"""
+
+    def __init__(self, *components):  # <1>
+        self._components = tuple(components)  # <2>
+
+    def __repr__(self):
+        return 'Vector' + (reprlib.repr(self._components))  # <3>
+
+    def __iter__(self):
+        return iter(self._components)  # <4>
+
+    def __abs__(self):
+        return math.sqrt(sum(comp*comp for comp in self)) # <5>
+
+    def __len__(self):
+        return len(self._components)  # <6>
+
+    def __add__(self, other):
+        if len(self) != len(other):
+            raise ValueError(EQ_DIMENSIONS_MSG % 'Addition')
+        return Vector(*(a+b for a, b in zip(self, other)))  # <7>
+
+    def __mul__(self, other):
+        if isinstance(other, numbers.Number):
+            return Vector(*(comp*other for comp in self))  # <8>
+        else:
+            return self.elementwise_mul(other)  # <9>
+
+    def elementwise_mul(self, other):
+        if len(self) != len(other):
+            raise ValueError(EQ_DIMENSIONS_MSG %
+                             'Elementwise multiplication')
+        return Vector(*(a*b for a, b in zip(self, other)))  # <10>
+
+    def __bool__(self):
+        return any(self)  # <11>
+# END VECTOR_ITER

iterables/vector_flex_init.py

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+"""
+A more flexible `__init__` for the Vector class
+
+A Vector can be built from an iterable:
+
+    >>> Vector([10, 20, 30])
+    Vector(10, 20, 30)
+    >>> Vector(range(1, 5))
+    Vector(1, 2, 3, 4)
+
+Or from two more arguments:
+
+    >>> Vector(100, 200)
+    Vector(100, 200)
+    >>> Vector(1, 2, 3, 4, 5)
+    Vector(1, 2, 3, 4, 5)
+
+One-dimensional vectors are not supported:
+
+    >>> Vector(99)
+    Traceback (most recent call last):
+       ...
+    TypeError: Vector() takes one iterable argument or at least 2 scalar arguments
+
+"""
+
+import reprlib
+
+
+class Vector:
+    """An n-dimensional vector"""
+
+    def __init__(self, first, *rest):  # <1>
+        if rest:
+            self._components = (first,) + tuple(rest)  # <3>
+        else:
+            try:
+                self._components = tuple(first)  # <2>
+            except TypeError:
+                raise TypeError('Vector() takes one iterable argument or at least 2 scalar arguments')
+
+    def __repr__(self):
+        return 'Vector' + reprlib.repr(self._components)