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fxadecimal/Yield-Magic.ipynb

Created March 12, 2021 11:44
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Yield-Magic.ipynb
{
"cells": [
{
"cell_type": "markdown",
"id": "comparative-processing",
"metadata": {},
"source": [
"# The magic of Yield"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "accompanied-dubai",
"metadata": {},
"outputs": [],
"source": [
"import pprint\n",
"pp = pprint.PrettyPrinter(indent=4)"
]
},
{
"cell_type": "markdown",
"id": "horizontal-albany",
"metadata": {},
"source": [
"## Iterators \n",
"\n",
"An iterable is any Python object capable of returning its members one at a time, permitting it to be iterated over in a for-loop.\n",
"\n",
"[https://www.pythonlikeyoumeanit.com/Module2_EssentialsOfPython/Iterables.html]()"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "color-niger",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"1\n",
"2\n",
"3\n"
]
}
],
"source": [
"l = list([1,2,3])\n",
"\n",
"for item in iter(l):\n",
" print( item )\n",
" \n",
"\n",
"\n"
]
},
{
"cell_type": "markdown",
"id": "regulated-typing",
"metadata": {},
"source": [
"## Generators\n",
"\n",
"- Either a Generator function that contains the `Yield` function\n",
"- Generator class implementing the python magic methods `__iter__()` or `__next__()`\n",
"- With `__iter__()`, returning something iteratable, that implements the `__next__()` method\n",
"\n",
"\n",
"References\n",
"- [https://wiki.python.org/moin/Generators](https://wiki.python.org/moin/Generators)\n",
"- [https://www.programiz.com/python-programming/generator](https://www.programiz.com/python-programming/generator)\n"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "hearing-bubble",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"<class 'range'>\n",
"[ '__bool__',\n",
" '__class__',\n",
" '__contains__',\n",
" '__delattr__',\n",
" '__dir__',\n",
" '__doc__',\n",
" '__eq__',\n",
" '__format__',\n",
" '__ge__',\n",
" '__getattribute__',\n",
" '__getitem__',\n",
" '__gt__',\n",
" '__hash__',\n",
" '__init__',\n",
" '__init_subclass__',\n",
" '__iter__',\n",
" '__le__',\n",
" '__len__',\n",
" '__lt__',\n",
" '__ne__',\n",
" '__new__',\n",
" '__reduce__',\n",
" '__reduce_ex__',\n",
" '__repr__',\n",
" '__reversed__',\n",
" '__setattr__',\n",
" '__sizeof__',\n",
" '__str__',\n",
" '__subclasshook__',\n",
" 'count',\n",
" 'index',\n",
" 'start',\n",
" 'step',\n",
" 'stop']\n",
"<range_iterator object at 0x1032623f0>\n",
"0\n",
"1\n",
"2\n",
"3\n",
"4\n",
"5\n",
"6\n",
"7\n",
"8\n",
"9\n"
]
}
],
"source": [
"# range was formally xrange in python2\n",
"\n",
"l = range(10) # range generator\n",
"\n",
"\n",
"# what is the python class? range!\n",
"print(type(l))\n",
"\n",
"# what are it's methods?\n",
"pp.pprint(dir(l)) # Note the __iter__ method\n",
"\n",
"\n",
"print( iter(l) ) # gives us a range_iterator to iterate over the range object\n",
"\n",
"for i in iter(l):\n",
" print(i)\n",
"\n",
"\n"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "breeding-connectivity",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"0\n",
"10\n"
]
}
],
"source": [
"def generator_function(initial_value = 0):\n",
" num = initial_value\n",
" while True:\n",
" yield num # < note the yield\n",
" num += 10\n",
" \n",
"gen = generator_function()\n",
"print( next(gen) )\n",
"print( next(gen) )\n"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "boxed-millennium",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"1\n",
"2\n",
"4\n",
"8\n",
"16\n",
"32\n",
"64\n",
"128\n",
"256\n",
"512\n"
]
}
],
"source": [
"# generator class\n",
"\n",
"class PowTwo:\n",
" def __init__(self, max=0):\n",
" self.n = 0\n",
" self.max = max\n",
"\n",
" def __iter__(self):\n",
" return self\n",
"\n",
" def __next__(self):\n",
" if self.n > self.max:\n",
" raise StopIteration\n",
"\n",
" result = 2 ** self.n\n",
" self.n += 1\n",
" return result\n",
" \n",
" \n",
"powtwo = PowTwo( 10 )\n",
"powtwo_iteratable = iter(powtwo) # calls __iter__()\n",
"\n",
"for i in range(0,10):\n",
" print( next(powtwo) ) # changes state of powtwo\n"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "designing-crowd",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"1\n",
"2\n",
"4\n",
"8\n",
"16\n",
"32\n",
"64\n",
"128\n",
"256\n",
"512\n"
]
}
],
"source": [
"# simplify the generator class to a generator function\n",
"\n",
"def PowTwoGen(max=0):\n",
" n = 0\n",
" while n < max:\n",
" yield 2 ** n\n",
" n += 1\n",
"\n",
" \n",
"powtwo_iteratable = PowTwoGen(10) \n",
"for i in range(0,10):\n",
" print( next(powtwo_iteratable) ) "
]
},
{
"cell_type": "markdown",
"id": "dirty-airfare",
"metadata": {},
"source": [
"## Yield\n",
"\n"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "adequate-slave",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"10\n",
"20\n",
"30\n",
"40\n",
"50\n",
"60\n",
"70\n",
"80\n",
"90\n",
"100\n"
]
}
],
"source": [
"\n",
"\n",
"def generator_function(initial_value = 10):\n",
" num = initial_value\n",
" while True:\n",
" yield num # < note the yield\n",
" num += 10\n",
"\n",
"gen = generator_function() \n",
"for i in range(0,10):\n",
" print( next(gen) ) # generator doesn't get resolved until we hit next\n",
" "
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "valuable-fishing",
"metadata": {},
"outputs": [],
"source": []
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.9.1"
}
},
"nbformat": 4,
"nbformat_minor": 5
}
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