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Reworked notebook: Added more detail to constraints and test cases. Reworked code and unit test.

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Donne Martin 2015-06-27 06:39:33 -04:00
parent 83e6b5b44d
commit fea843789b
1 changed files with 71 additions and 26 deletions
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97
sorting-searching/quick-sort.ipynb
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@ -13,10 +13,11 @@
"source": [ "source": [
"## Problem: Implement quick sort.\n", "## Problem: Implement quick sort.\n",
"\n", "\n",
"* [Clarifying Questions](#Clarifying-Questions)\n", "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n",
"* [Test Cases](#Test-Cases)\n", "* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n", "* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n", "* [Code](#Code)\n",
"* [Unit Test](#Unit-Test)\n",
"* [Pythonic-Code](#Pythonic-Code)" "* [Pythonic-Code](#Pythonic-Code)"
] ]
}, },
@ -24,9 +25,11 @@
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
"source": [ "source": [
"## Clarifying Questions\n", "## Constraints and Assumptions\n",
"\n", "\n",
"* Is a naiive quicksort (ie not in-place) ok?\n", "*Problem statements are often intentionally ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
"\n",
"* Are you looking for a naiive solution (ie not in-place)?\n",
" * Yes" " * Yes"
] ]
}, },
@ -73,7 +76,7 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 1,
"metadata": { "metadata": {
"collapsed": false "collapsed": false
}, },
@ -98,25 +101,6 @@
" return left + [pivot_value] + right" " return left + [pivot_value] + right"
] ]
}, },
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"print('Empty input')\n",
"data = []\n",
"print(quick_sort(data))\n",
"print('One element')\n",
"data = [5]\n",
"print(quick_sort(data))\n",
"print('Two or more elements')\n",
"data = [5, 1, 7, 2, 6, -3, 5, 7, -1]\n",
"print(quick_sort(data))"
]
},
{ {
"cell_type": "markdown", "cell_type": "markdown",
"metadata": {}, "metadata": {},
@ -128,17 +112,78 @@
}, },
{ {
"cell_type": "code", "cell_type": "code",
"execution_count": null, "execution_count": 2,
"metadata": { "metadata": {
"collapsed": true "collapsed": true
}, },
"outputs": [], "outputs": [],
"source": [ "source": [
"def quick_sort(arr): \n", "def quick_sort_alt(arr): \n",
" if len(arr) <= 1:\n", " if len(arr) <= 1:\n",
" return arr\n", " return arr\n",
" else:\n", " else:\n",
" return qsort([x for x in arr[1:] if x<arr[0]]) + [arr[0]] + qsort([x for x in arr[1:] if x>=arr[0]])" " return quick_sort_alt([x for x in arr[1:] if x<arr[0]]) + [arr[0]] + quick_sort_alt([x for x in arr[1:] if x>=arr[0]])"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Unit Test\n",
"\n",
"*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand. You generally will not be asked to write a unit test like what is shown below.*"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Empty input\n",
"One element\n",
"Two or more elements\n",
"Success: test_quick_sort\n",
"\n",
"Empty input\n",
"One element\n",
"Two or more elements\n",
"Success: test_quick_sort\n",
"\n"
]
}
],
"source": [
"from nose.tools import assert_equal\n",
"\n",
"class Test(object):\n",
" def test_quick_sort(self, func):\n",
" print('Empty input')\n",
" data = []\n",
" func(data)\n",
" assert_equal(data, [])\n",
"\n",
" print('One element')\n",
" data = [5]\n",
" func(data)\n",
" assert_equal(data, [5])\n",
"\n",
" print('Two or more elements')\n",
" data = [5, 1, 7, 2, 6, -3, 5, 7, -1]\n",
" data = func(data)\n",
" assert_equal(data, sorted(data))\n",
" \n",
" print('Success: test_quick_sort\\n')\n",
"\n",
"if __name__ == '__main__':\n",
" test = Test()\n",
" test.test_quick_sort(quick_sort)\n",
" test.test_quick_sort(quick_sort_alt)"
] ]
} }
], ],