mirror of
https://github.com/rasbt/python_reference.git
synced 2024-10-06 04:59:28 +00:00
oddities
This commit is contained in:
rasbt
parent
5defb60d6e
commit
e6d80b066b
331
.ipynb_checkpoints/not_so_obvious_python_stuff-checkpoint.ipynb
Normal file
331
.ipynb_checkpoints/not_so_obvious_python_stuff-checkpoint.ipynb
Normal file
|
|
@ -0,0 +1,331 @@
|
|||
{
|
||||
"metadata": {
|
||||
"name": "",
|
||||
"signature": "sha256:437ca0df14a08cf4fd584f91122010286928f287ae14c5ac1ce8230abe9dbf9a"
|
||||
},
|
||||
"nbformat": 3,
|
||||
"nbformat_minor": 0,
|
||||
"worksheets": [
|
||||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"Sebastian Raschka \n",
|
||||
"last updated: 04/15/2014"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"All code was executed in Python 3.4"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# A collection of not so obvious Python stuff you should know!"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Sections\n",
|
||||
"- [The C3 class resolution algorithm for multiple class inheritance](#c3_class_res)\n",
|
||||
"- [The behavior of += for lists](#pm_in_lists)\n",
|
||||
"- [`True` and `False` in the datetime module](#datetime_module)\n",
|
||||
"- [Some Python Oddity that I cannot explain, yet](#python_oddity)\n",
|
||||
"- [Shallow vs. deep copies if list contains other structures and objects](#shallow_vs_deep)\n",
|
||||
"- [Picking True values from and and or expressions](#false_true_expressions)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='c3_class_res'></a>\n",
|
||||
"## The C3 class resolution algorithm for multiple class inheritance"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"If we are dealing with multiple inheritance, according to the newer C3 class resolution algorithm, the following applies: \"class A should be checked before class B\".\n",
|
||||
"\n",
|
||||
"If you want to learn more, please read the [original blog](http://python-history.blogspot.ru/2010/06/method-resolution-order.html) post by Guido van Rossum.\n",
|
||||
"\n",
|
||||
"(Original source: [http://gistroll.com/rolls/21/horizontal_assessments/new](http://gistroll.com/rolls/21/horizontal_assessments/new))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"class A(object):\n",
|
||||
" def foo(self):\n",
|
||||
" print(\"class A\")\n",
|
||||
"\n",
|
||||
"class B(object):\n",
|
||||
" def foo(self):\n",
|
||||
" print(\"class B\")\n",
|
||||
"\n",
|
||||
"class C(A, B):\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
"C().foo()"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"class A\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 2
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='pm_in_lists'></a>\n",
|
||||
"## The behavior of `+=` for lists"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"If we are using the `+=` operator on lists, we extend the list by modifying the object directly. However, if we use the assigment via `my_list = my_list + ...`, we create a new list object, which can be demonstrated by the following code:\n",
|
||||
"\n",
|
||||
"(Original source: [http://stackoverflow.com/questions/2347265/why-does-behave-unexpectedly-on-lists](http://stackoverflow.com/questions/2347265/why-does-behave-unexpectedly-on-lists))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"list_a = []\n",
|
||||
"print('ID of list_a', id(list_a))\n",
|
||||
"list_a += [1]\n",
|
||||
"print('ID of list_a after `+= [1]`', id(list_a))\n",
|
||||
"list_a = list_a + [2]\n",
|
||||
"print('ID of list_a after `list_a = list_a + [2]`', id(list_a))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"ID of list_a 4356439144\n",
|
||||
"ID of list_a after `+= [1]` 4356439144\n",
|
||||
"ID of list_a after `list_a = list_a + [2]` 4356446112\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 3
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='datetime_module'></a>\n",
|
||||
"## `True` and `False` in the datetime module\n",
|
||||
"\n",
|
||||
"\"it often comes as a big surprise for programmers to find (sometimes by way of a hard-to-reproduce bug) that,\n",
|
||||
"unlike any other time value, midnight (i.e. datetime.time(0,0,0)) is False.\n",
|
||||
"A long discussion on the python-ideas mailing list shows that, while surprising,\n",
|
||||
"that behavior is desirable\u2014at least in some quarters.\"\n",
|
||||
"\n",
|
||||
"(Original source: [http://lwn.net/SubscriberLink/590299/bf73fe823974acea/](http://lwn.net/SubscriberLink/590299/bf73fe823974acea/))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"import datetime\n",
|
||||
"\n",
|
||||
"print('\"datetime.time(0,0,0)\" (Midnight) evaluates to', bool(datetime.time(0,0,0)))\n",
|
||||
"\n",
|
||||
"print('\"datetime.time(1,0,0)\" (1 am) evaluates to', bool(datetime.time(1,0,0)))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"\"datetime.time(0,0,0)\" (Midnight) evaluates to False\n",
|
||||
"\"datetime.time(1,0,0)\" (1 am) evaluates to True\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 4
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='python_oddity'></a>\n",
|
||||
"## Some Python Oddity that I cannot explain, yet"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"a = 1\n",
|
||||
"b = 1\n",
|
||||
"print('a is b', bool(a is b))\n",
|
||||
"True\n",
|
||||
"\n",
|
||||
"a = 999\n",
|
||||
"b = 999\n",
|
||||
"print('a is b', bool(a is b))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"a is b True\n",
|
||||
"a is b False\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 5
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='shallow_vs_deep'></a>\n",
|
||||
"## Shallow vs. deep copies if list contains other structures and objects\n",
|
||||
"\n",
|
||||
"List modification of the original list does affect shallow copies, but not deep copies if the list contains compound objects."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"from copy import deepcopy\n",
|
||||
"\n",
|
||||
"my_first_list = [[1],[2]]\n",
|
||||
"my_second_list = [[1],[2]]\n",
|
||||
"print('my_first_list == my_second_list:', my_first_list == my_second_list)\n",
|
||||
"print('my_first_list is my_second_list:', my_first_list is my_second_list)\n",
|
||||
"\n",
|
||||
"my_third_list = my_first_list\n",
|
||||
"print('my_first_list == my_third_list:', my_first_list == my_third_list)\n",
|
||||
"print('my_first_list is my_third_list:', my_first_list is my_third_list)\n",
|
||||
"\n",
|
||||
"my_shallow_copy = my_first_list[:]\n",
|
||||
"print('my_first_list == my_shallow_copy:', my_first_list == my_shallow_copy)\n",
|
||||
"print('my_first_list is my_shallow_copy:', my_first_list is my_shallow_copy)\n",
|
||||
"\n",
|
||||
"my_deep_copy = deepcopy(my_first_list)\n",
|
||||
"print('my_first_list == my_deep_copy:', my_first_list == my_deep_copy)\n",
|
||||
"print('my_first_list is my_deep_copy:', my_first_list is my_deep_copy)\n",
|
||||
"\n",
|
||||
"print('\\nmy_third_list:', my_third_list)\n",
|
||||
"print('my_shallow_copy:', my_shallow_copy)\n",
|
||||
"print('my_deep_copy:', my_deep_copy)\n",
|
||||
"\n",
|
||||
"my_first_list[0][0] = 2\n",
|
||||
"print('after setting \"my_first_list[0][0] = 2\"')\n",
|
||||
"print('my_third_list:', my_third_list)\n",
|
||||
"print('my_shallow_copy:', my_shallow_copy)\n",
|
||||
"print('my_deep_copy:', my_deep_copy)"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"my_first_list == my_second_list: True\n",
|
||||
"my_first_list is my_second_list: False\n",
|
||||
"my_first_list == my_third_list: True\n",
|
||||
"my_first_list is my_third_list: True\n",
|
||||
"my_first_list == my_shallow_copy: True\n",
|
||||
"my_first_list is my_shallow_copy: False\n",
|
||||
"my_first_list == my_deep_copy: True\n",
|
||||
"my_first_list is my_deep_copy: False\n",
|
||||
"\n",
|
||||
"my_third_list: [[1], [2]]\n",
|
||||
"my_shallow_copy: [[1], [2]]\n",
|
||||
"my_deep_copy: [[1], [2]]\n",
|
||||
"after setting \"my_first_list[0][0] = 2\"\n",
|
||||
"my_third_list: [[2], [2]]\n",
|
||||
"my_shallow_copy: [[2], [2]]\n",
|
||||
"my_deep_copy: [[1], [2]]\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 7
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='false_true_expressions'></a>\n",
|
||||
"## Picking `True` values from `and` and `or` expressions\n",
|
||||
"\n",
|
||||
"If both values of in a `or` expression are True, Python will select the first one, and the second one in `and` expressions\n",
|
||||
"\n",
|
||||
"(Original source: [http://gistroll.com/rolls/21/horizontal_assessments/new](http://gistroll.com/rolls/21/horizontal_assessments/new))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"result = (2 or 3) * (5 and 7)\n",
|
||||
"print('2 * 7 =', result)"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"2 * 7 = 14\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 9
|
||||
}
|
||||
],
|
||||
"metadata": {}
|
||||
}
|
||||
]
|
||||
}
|
||||
331
not_so_obvious_python_stuff.ipynb
Normal file
331
not_so_obvious_python_stuff.ipynb
Normal file
|
|
@ -0,0 +1,331 @@
|
|||
{
|
||||
"metadata": {
|
||||
"name": "",
|
||||
"signature": "sha256:437ca0df14a08cf4fd584f91122010286928f287ae14c5ac1ce8230abe9dbf9a"
|
||||
},
|
||||
"nbformat": 3,
|
||||
"nbformat_minor": 0,
|
||||
"worksheets": [
|
||||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"Sebastian Raschka \n",
|
||||
"last updated: 04/15/2014"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"All code was executed in Python 3.4"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# A collection of not so obvious Python stuff you should know!"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Sections\n",
|
||||
"- [The C3 class resolution algorithm for multiple class inheritance](#c3_class_res)\n",
|
||||
"- [The behavior of += for lists](#pm_in_lists)\n",
|
||||
"- [`True` and `False` in the datetime module](#datetime_module)\n",
|
||||
"- [Some Python Oddity that I cannot explain, yet](#python_oddity)\n",
|
||||
"- [Shallow vs. deep copies if list contains other structures and objects](#shallow_vs_deep)\n",
|
||||
"- [Picking True values from and and or expressions](#false_true_expressions)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='c3_class_res'></a>\n",
|
||||
"## The C3 class resolution algorithm for multiple class inheritance"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"If we are dealing with multiple inheritance, according to the newer C3 class resolution algorithm, the following applies: \"class A should be checked before class B\".\n",
|
||||
"\n",
|
||||
"If you want to learn more, please read the [original blog](http://python-history.blogspot.ru/2010/06/method-resolution-order.html) post by Guido van Rossum.\n",
|
||||
"\n",
|
||||
"(Original source: [http://gistroll.com/rolls/21/horizontal_assessments/new](http://gistroll.com/rolls/21/horizontal_assessments/new))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"class A(object):\n",
|
||||
" def foo(self):\n",
|
||||
" print(\"class A\")\n",
|
||||
"\n",
|
||||
"class B(object):\n",
|
||||
" def foo(self):\n",
|
||||
" print(\"class B\")\n",
|
||||
"\n",
|
||||
"class C(A, B):\n",
|
||||
" pass\n",
|
||||
"\n",
|
||||
"C().foo()"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"class A\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 2
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='pm_in_lists'></a>\n",
|
||||
"## The behavior of `+=` for lists"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"If we are using the `+=` operator on lists, we extend the list by modifying the object directly. However, if we use the assigment via `my_list = my_list + ...`, we create a new list object, which can be demonstrated by the following code:\n",
|
||||
"\n",
|
||||
"(Original source: [http://stackoverflow.com/questions/2347265/why-does-behave-unexpectedly-on-lists](http://stackoverflow.com/questions/2347265/why-does-behave-unexpectedly-on-lists))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"list_a = []\n",
|
||||
"print('ID of list_a', id(list_a))\n",
|
||||
"list_a += [1]\n",
|
||||
"print('ID of list_a after `+= [1]`', id(list_a))\n",
|
||||
"list_a = list_a + [2]\n",
|
||||
"print('ID of list_a after `list_a = list_a + [2]`', id(list_a))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"ID of list_a 4356439144\n",
|
||||
"ID of list_a after `+= [1]` 4356439144\n",
|
||||
"ID of list_a after `list_a = list_a + [2]` 4356446112\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 3
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='datetime_module'></a>\n",
|
||||
"## `True` and `False` in the datetime module\n",
|
||||
"\n",
|
||||
"\"it often comes as a big surprise for programmers to find (sometimes by way of a hard-to-reproduce bug) that,\n",
|
||||
"unlike any other time value, midnight (i.e. datetime.time(0,0,0)) is False.\n",
|
||||
"A long discussion on the python-ideas mailing list shows that, while surprising,\n",
|
||||
"that behavior is desirable\u2014at least in some quarters.\"\n",
|
||||
"\n",
|
||||
"(Original source: [http://lwn.net/SubscriberLink/590299/bf73fe823974acea/](http://lwn.net/SubscriberLink/590299/bf73fe823974acea/))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"import datetime\n",
|
||||
"\n",
|
||||
"print('\"datetime.time(0,0,0)\" (Midnight) evaluates to', bool(datetime.time(0,0,0)))\n",
|
||||
"\n",
|
||||
"print('\"datetime.time(1,0,0)\" (1 am) evaluates to', bool(datetime.time(1,0,0)))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"\"datetime.time(0,0,0)\" (Midnight) evaluates to False\n",
|
||||
"\"datetime.time(1,0,0)\" (1 am) evaluates to True\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 4
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='python_oddity'></a>\n",
|
||||
"## Some Python Oddity that I cannot explain, yet"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"a = 1\n",
|
||||
"b = 1\n",
|
||||
"print('a is b', bool(a is b))\n",
|
||||
"True\n",
|
||||
"\n",
|
||||
"a = 999\n",
|
||||
"b = 999\n",
|
||||
"print('a is b', bool(a is b))"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"a is b True\n",
|
||||
"a is b False\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 5
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='shallow_vs_deep'></a>\n",
|
||||
"## Shallow vs. deep copies if list contains other structures and objects\n",
|
||||
"\n",
|
||||
"List modification of the original list does affect shallow copies, but not deep copies if the list contains compound objects."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"from copy import deepcopy\n",
|
||||
"\n",
|
||||
"my_first_list = [[1],[2]]\n",
|
||||
"my_second_list = [[1],[2]]\n",
|
||||
"print('my_first_list == my_second_list:', my_first_list == my_second_list)\n",
|
||||
"print('my_first_list is my_second_list:', my_first_list is my_second_list)\n",
|
||||
"\n",
|
||||
"my_third_list = my_first_list\n",
|
||||
"print('my_first_list == my_third_list:', my_first_list == my_third_list)\n",
|
||||
"print('my_first_list is my_third_list:', my_first_list is my_third_list)\n",
|
||||
"\n",
|
||||
"my_shallow_copy = my_first_list[:]\n",
|
||||
"print('my_first_list == my_shallow_copy:', my_first_list == my_shallow_copy)\n",
|
||||
"print('my_first_list is my_shallow_copy:', my_first_list is my_shallow_copy)\n",
|
||||
"\n",
|
||||
"my_deep_copy = deepcopy(my_first_list)\n",
|
||||
"print('my_first_list == my_deep_copy:', my_first_list == my_deep_copy)\n",
|
||||
"print('my_first_list is my_deep_copy:', my_first_list is my_deep_copy)\n",
|
||||
"\n",
|
||||
"print('\\nmy_third_list:', my_third_list)\n",
|
||||
"print('my_shallow_copy:', my_shallow_copy)\n",
|
||||
"print('my_deep_copy:', my_deep_copy)\n",
|
||||
"\n",
|
||||
"my_first_list[0][0] = 2\n",
|
||||
"print('after setting \"my_first_list[0][0] = 2\"')\n",
|
||||
"print('my_third_list:', my_third_list)\n",
|
||||
"print('my_shallow_copy:', my_shallow_copy)\n",
|
||||
"print('my_deep_copy:', my_deep_copy)"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"my_first_list == my_second_list: True\n",
|
||||
"my_first_list is my_second_list: False\n",
|
||||
"my_first_list == my_third_list: True\n",
|
||||
"my_first_list is my_third_list: True\n",
|
||||
"my_first_list == my_shallow_copy: True\n",
|
||||
"my_first_list is my_shallow_copy: False\n",
|
||||
"my_first_list == my_deep_copy: True\n",
|
||||
"my_first_list is my_deep_copy: False\n",
|
||||
"\n",
|
||||
"my_third_list: [[1], [2]]\n",
|
||||
"my_shallow_copy: [[1], [2]]\n",
|
||||
"my_deep_copy: [[1], [2]]\n",
|
||||
"after setting \"my_first_list[0][0] = 2\"\n",
|
||||
"my_third_list: [[2], [2]]\n",
|
||||
"my_shallow_copy: [[2], [2]]\n",
|
||||
"my_deep_copy: [[1], [2]]\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 7
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<br>\n",
|
||||
"<br>\n",
|
||||
"<a name='false_true_expressions'></a>\n",
|
||||
"## Picking `True` values from `and` and `or` expressions\n",
|
||||
"\n",
|
||||
"If both values of in a `or` expression are True, Python will select the first one, and the second one in `and` expressions\n",
|
||||
"\n",
|
||||
"(Original source: [http://gistroll.com/rolls/21/horizontal_assessments/new](http://gistroll.com/rolls/21/horizontal_assessments/new))"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"collapsed": false,
|
||||
"input": [
|
||||
"result = (2 or 3) * (5 and 7)\n",
|
||||
"print('2 * 7 =', result)"
|
||||
],
|
||||
"language": "python",
|
||||
"metadata": {},
|
||||
"outputs": [
|
||||
{
|
||||
"output_type": "stream",
|
||||
"stream": "stdout",
|
||||
"text": [
|
||||
"2 * 7 = 14\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"prompt_number": 9
|
||||
}
|
||||
],
|
||||
"metadata": {}
|
||||
}
|
||||
]
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user