From e0b8a991933a6a983e69393e03b5a026515d8ac4 Mon Sep 17 00:00:00 2001
From: Louis Oliphant <ltoliphant@wisc.edu>
Date: Sun, 27 Oct 2024 22:43:19 -0500
Subject: [PATCH] Finished Lec 23
---
.../Lec_23_Function_References.ipynb | 264 ++++++++
...Lec_23_Function_References_Solution.ipynb} | 578 ++++++++++--------
2 files changed, 572 insertions(+), 270 deletions(-)
rename f24/Louis_Lecture_Notes/23_Function_References/{Lec_23_Function_References_Solution_Oliphant.ipynb => Lec_23_Function_References_Solution.ipynb} (90%)
diff --git a/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References.ipynb b/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References.ipynb
index 52fdc1c..8949d1b 100644
--- a/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References.ipynb
+++ b/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References.ipynb
@@ -45,6 +45,7 @@
},
{
"cell_type": "code",
+<<<<<<< HEAD
"execution_count": 1,
"metadata": {},
"outputs": [
@@ -59,6 +60,11 @@
"output_type": "execute_result"
}
],
+=======
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+>>>>>>> f9e9c99 (finished lec 23 function references)
"source": [
"# Warmup 2: Trace Recursion by hand .... possible exam question\n",
"\n",
@@ -85,11 +91,19 @@
"\n",
"- [Python for Everybody, 10.8](https://runestone.academy/ns/books/published/py4e-int/dictionaries/toctree.html)\n",
"\n",
+<<<<<<< HEAD
"As we have learned previously, all variables in Python refer to objects.\n",
"\n",
"This is also true for functions -- their name refers to a function object, and it gives us more power as programmers.\n",
"\n",
"## Learning Objectives\n",
+=======
+ "As we have learned previously, all variables contain references to objects.\n",
+ "\n",
+ "This is also true for function names, and it gives us more power as programmers.\n",
+ "\n",
+ "**Learning Objectives:**\n",
+>>>>>>> f9e9c99 (finished lec 23 function references)
"\n",
"- Define a function reference and trace code that uses function references.\n",
"- Explain the default use of sorted() on lists of tuples, and dictionaries.\n",
@@ -98,6 +112,7 @@
]
},
{
+<<<<<<< HEAD
"cell_type": "markdown",
"metadata": {},
"source": [
@@ -137,6 +152,8 @@
]
},
{
+=======
+>>>>>>> f9e9c99 (finished lec 23 function references)
"cell_type": "code",
"execution_count": null,
"metadata": {},
@@ -146,6 +163,7 @@
"# try this in Python Tutor\n",
"\n",
"x = [1,2,3]\n",
+<<<<<<< HEAD
"y = x\n",
"\n",
"def f(some_list): # what is f? \n",
@@ -156,6 +174,22 @@
"g = f # what is g?\n",
"\n",
"# TODO: Try calling the function using the variable g\n"
+=======
+ "y = x # y holds a reference to the same object as x\n",
+ "\n",
+ "def f(some_list): # f is the name of the function\n",
+ " return some_list[-1]\n",
+ "\n",
+ "z = f(y) # z stores the result of a call to f\n",
+ "\n",
+ "g = f # g holds a reference to the same function as f\n",
+ "\n",
+ "# TODO: similar to calling f() and storing the result in z, but now call g and store the results in z2\n",
+ "\n",
+ "\n",
+ "print(z)\n",
+ "print(z2)"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -181,12 +215,17 @@
"cell_type": "markdown",
"metadata": {},
"source": [
+<<<<<<< HEAD
"## Functions can be passed as arguments!\n",
"Take a look at the code below. Watch it run using [PythonTutor](https://pythontutor.com/render.html#code=def%20hammer%28%29%3A%0A%20%20%20%20print%28%22tap%20tap%20tap%22%29%0A%0Adef%20call_n_times%28f,%20n%29%3A%0A%20%20%20%20for%20i%20in%20range%28n%29%3A%0A%20%20%20%20%20%20%20%20f%28%29%0A%0Acall_n_times%28hammer,%203%29&cumulative=false&curInstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false). Then modify the code to finish the `screwdriver()` function and write a line of code to call `call_n_times()` passing in as arguments your `screwdriver` function and the value 5."
+=======
+ "[PythonTutor Link](https://pythontutor.com/visualize.html#code=def%20hammer%28%29%3A%0A%20%20%20%20print%28%22tap%20tap%20tap%22%29%0A%20%20%20%20%0Adef%20call_n_times%28f,%20n%29%3A%0A%20%20%20%20for%20i%20in%20range%28n%29%3A%0A%20%20%20%20%20%20%20%20f%28%29%0A%0Acall_n_times%28hammer,%203%29&cumulative=false&curInstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false)"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
"cell_type": "code",
+<<<<<<< HEAD
"execution_count": 2,
"metadata": {},
"outputs": [
@@ -202,6 +241,13 @@
],
"source": [
"# function references can be passed as arguments ...Wow!\n",
+=======
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# function references can be passed as arguments ... Wow!\n",
+>>>>>>> f9e9c99 (finished lec 23 function references)
"\n",
"# first: try this in Python Tutor\n",
"\n",
@@ -291,7 +337,15 @@
"source": [
"We already did the math behind `manhattan_distance` and `euclidean_distance` for you!\n",
"\n",
+<<<<<<< HEAD
"**Hint:** `distance_algo` should be a reference to a function that calculates distance between two points.\n",
+=======
+ "Finish writing the `calculate_distances()` function, which should go over every point in `left_point`\n",
+ "and print the point, the matching point in `right_point` and the distance between them.\n",
+ "\n",
+ "**Hint:** The `distance_algo` parameter should be a reference to a function that calculates the distance between two points.\n",
+ "\n",
+>>>>>>> f9e9c99 (finished lec 23 function references)
"\n",
"Then, call calculate_distances measuring first in manhattan_distance, then euclidean_distance."
]
@@ -326,7 +380,18 @@
"cell_type": "markdown",
"metadata": {},
"source": [
+<<<<<<< HEAD
"### Explain the default use of sorted() on lists of tuples, and on dictionaries.\n"
+=======
+ "### Explain the default use of sorted() on lists of tuples, and on dictionaries.\n",
+ "\n",
+ "The `sort()` method and the `sorted()` function have two optional arguments, `key` and `reverse`. These\n",
+ "arguments control how the list will be sorted. The `reverse` argument defaults to `False`, but if you set\n",
+ "it to true then the list will be sorted in reverse order.\n",
+ "\n",
+ "Take a look at the help function for `sorted()` in the cell below then try sorting the `populations` \n",
+ "list, first in sorted order then in reverse sorted order."
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -335,14 +400,20 @@
"metadata": {},
"outputs": [],
"source": [
+<<<<<<< HEAD
"# first... did you know that sort/sorted takes a 2nd argument called reverse?\n",
"\n",
"populations = [55, 77, 33, 99, 22]\n",
"# TODO: sort populations in reverse"
+=======
+ "# print out the help for the sorted function and read about the reverse and key parameters\n",
+ "help(sorted)"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
"cell_type": "code",
+<<<<<<< HEAD
"execution_count": 1,
"metadata": {},
"outputs": [
@@ -362,6 +433,40 @@
"output_type": "execute_result"
}
],
+=======
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "populations = [55, 77, 33, 99, 22]\n",
+ "# TODO: sort populations then sort again in reverse order"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## The `key` parameter in `sort()` and `sorted()`\n",
+ "\n",
+ "The `key` parameter is a function that can be used to customize how the list will be sorted.\n",
+ "This is especially useful when sorting things where it is not clear what their order should be or if you\n",
+ "want to change the default soriting behavior. The function that should be passed to `key` takes as input\n",
+ "one item at a time from the list and it should return something that the `sort()` or `sorted()`\n",
+ "function does know how to sort, like a string or a number.\n",
+ "\n",
+ "For example, take a look at the `owhockey_badgers` list below. Notice that the list contains tuples.\n",
+ "If you were to call `sort()` or `sorted()` on this list, the default behavior would be to sort using the first\n",
+ "item in each tuple, then the second, and so on.\n",
+ "\n",
+ "Run the code in the cell below to see the default sorting behavior."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+>>>>>>> f9e9c99 (finished lec 23 function references)
"source": [
"# Sorting part 1....how are lists of tuples sorted?\n",
"# olympic womens hockey badgers...first, last, age\n",
@@ -371,7 +476,12 @@
" (\"Amanda\", \"Kessel\", 30),\n",
" (\"Alex\", \"Cavalenni\", 30), \n",
" (\"Caroline\", \"Harvey\", 19),\n",
+<<<<<<< HEAD
" (\"Abbey\", \"Roque\", 24)\n",
+=======
+ " (\"Abbey\", \"Roquet\", 24),\n",
+ " (\"Abbey\", \"Roques\", 27)\n",
+>>>>>>> f9e9c99 (finished lec 23 function references)
" ]\n",
"\n",
"\n",
@@ -381,6 +491,20 @@
]
},
{
+<<<<<<< HEAD
+=======
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "If you want to have the list sorted by the age of each player, then you need to tell\n",
+ "the sorting algorithm which item to sort by. You can create a function that takes\n",
+ "as input a single item from the list and returns the value that you want to be used\n",
+ "when sorting. In the cell below three such functions are created to return the\n",
+ "item from the tuple that you want to use when sorting the list."
+ ]
+ },
+ {
+>>>>>>> f9e9c99 (finished lec 23 function references)
"cell_type": "code",
"execution_count": null,
"metadata": {},
@@ -396,7 +520,20 @@
"def select2(some_tuple):\n",
" return some_tuple[2]\n",
"\n",
+<<<<<<< HEAD
"# Test these functions on the tuple (\"Mike\", \"Gurmail\", \"Cole\")\n"
+=======
+ "# TODO: Test these functions on the tuple (\"Mike\", \"Louis\", \"Cole\")\n",
+ "test_tuple = (\"Mike\", \"Louis\", \"Cole\")\n",
+ "\n"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Try using each of these select functions as the key when sorting the `owhockey_badgers` list."
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -408,6 +545,7 @@
"# call sorted using the 'key' argument \n",
"# sort and sorted can take a parameter named key\n",
"# key is a reference to a function!\n",
+<<<<<<< HEAD
"sorted(owhockey_badgers, key=select2)"
]
},
@@ -427,12 +565,18 @@
"outputs": [],
"source": [
"# sort the list of tuples based on the age\n"
+=======
+ "# TODO: Try sorting by first name, last name, and age\n",
+ "\n",
+ "sorted(owhockey_badgers, key=...)"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
+<<<<<<< HEAD
"### Using `lambda`\n",
"- `lambda` functions are a way to abstract a function reference\n",
"- lambdas are simple functions with:\n",
@@ -446,6 +590,13 @@
"```python \n",
"lambda parameters: expression\n",
"```"
+=======
+ "The default behavior when sorting a list of dictionaries, is to fail. Python does not\n",
+ "know how to sort dictionaries. In this case you must have a `key` function that can extract\n",
+ "the right value so Python will know how to sort. Try sorting without passing a key function\n",
+ "to sort the list of dictionaries then write a function to get the `age` key from the dictionary\n",
+ "and use that when sorting."
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -454,6 +605,7 @@
"metadata": {},
"outputs": [],
"source": [
+<<<<<<< HEAD
"# sorting part 3....using lambdas\n",
"\n",
"'''\n",
@@ -464,12 +616,96 @@
"sorted(owhockey_badgers, key = lambda each_tuple : each_tuple[-1])\n",
"\n",
"# read the lambda as: my no-name function has each_tuple as a parameter\n",
+=======
+ "people = [\n",
+ " {'first':'Louis', 'last':'Oliphant', 'age':53},\n",
+ " {'first':'Becky', 'last':'Brown', 'age':52},\n",
+ " {'first':'Sam', 'last':'Luna-Nelson', 'age':26},\n",
+ " {'first':'Sally', 'last':'Fields', 'age':47}\n",
+ "]\n",
+ "\n",
+ "##TODO: first try sorting without passing a function for the key parameter\n",
+ "\n",
+ "sorted(people)\n",
+ " "
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "\n",
+ "##TODO: finish the get_age() function that takes a single dictionary and returns\n",
+ "## the age key from the dictionary.\n",
+ "\n",
+ "def get_age(d):\n",
+ " #return the 'age' key\n",
+ " pass\n",
+ "\n",
+ "##TODO: use the get_age function as the key and try sorting again\n",
+ "\n",
+ "sorted(people, key=...)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Using `lambda` functions\n",
+ "- `lambda` functions are a way to abstract a function reference\n",
+ "- lambdas are simple functions with:\n",
+ " - multiple possible parameters\n",
+ " - single **expression** line as the function body\n",
+ "- lambdas are useful abstractions for:\n",
+ " - mathematical functions\n",
+ " - lookup operations\n",
+ "- lambdas are often associated with a collection of values within a list\n",
+ "- Syntax:\n",
+ " \n",
+ "```python \n",
+ "lambda parameters: expression\n",
+ "```\n",
+ "\n",
+ "Here are some examples of creating a function using this lambda notation. Note that the variable holds the *function*. Below each creation of the function is a call to the function.\n",
+ "\n",
+ "```python\n",
+ "f = lambda a : a + 10\n",
+ "print(f(1))\n",
+ "```\n",
+ "```\n",
+ "11\n",
+ "```\n",
+ "```python\n",
+ "f2 = lambda a, b : a * b\n",
+ "print(f2(3,4))\n",
+ "```\n",
+ "```\n",
+ "12\n",
+ "```\n",
+ "\n",
+ "Let's use a lambda function to sort the `owhockey_badgers` tuple by the age (i.e. the last field)."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "\n",
+ "sorted(owhockey_badgers, key = lambda each_tuple : each_tuple[-1])\n",
+ "\n",
+ "# read the lambda as: my no-name function has each_tuple from owhockey_badgers as a parameter\n",
+>>>>>>> f9e9c99 (finished lec 23 function references)
"# and returns each_tuple[-1] (the last element)\n",
"# the variable 'each_tuple' is like a function parameter"
]
},
{
"cell_type": "code",
+<<<<<<< HEAD
"execution_count": 5,
"metadata": {},
"outputs": [
@@ -490,6 +726,15 @@
"def no_name(x):\n",
" return len(x[0])\n",
"'''"
+=======
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# TODO: sort the people list of dictionaries by the last name\n",
+ "\n",
+ "sorted(people, key = ...)"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -498,13 +743,20 @@
"metadata": {},
"outputs": [],
"source": [
+<<<<<<< HEAD
"# TODO: Sort the list by the length of their full name\n"
+=======
+ "# TODO: Sort the people list of dictionaries by the LENGTH of their last name\n",
+ "\n",
+ "sorted(people, key = ...)\n"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
+<<<<<<< HEAD
"### OK, I can sort a list of tuples....what about a list of dictionaries?"
]
},
@@ -562,6 +814,11 @@
"metadata": {},
"source": [
"### This is all great, but what I'd really like to do is to sort dictionaries!\n"
+=======
+ "### This is all great, but what I'd really like to do is to sort dictionaries!\n",
+ "\n",
+ "From Python 3.7 onwards, the standard dict type maintains insertion order by default ([see here](https://mail.python.org/pipermail/python-dev/2017-December/151283.html)), so a dictionary could be ordered, but what happens if you try and sort a dictionary?"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -602,7 +859,11 @@
"\n",
"# let's sort menu.items() the same way we sorted a list of tuples\n",
"\n",
+<<<<<<< HEAD
"sorted(menu.items(), key = lambda t : t[0] ) # set the sorting key to a lambda expressoin"
+=======
+ "sorted(menu.items(), key = lambda t : t[0] ) # set the sorting key to a lambda expression"
+>>>>>>> f9e9c99 (finished lec 23 function references)
]
},
{
@@ -625,6 +886,7 @@
]
},
{
+<<<<<<< HEAD
"cell_type": "code",
"execution_count": null,
"metadata": {},
@@ -634,6 +896,8 @@
]
},
{
+=======
+>>>>>>> f9e9c99 (finished lec 23 function references)
"cell_type": "markdown",
"metadata": {},
"source": [
diff --git a/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution_Oliphant.ipynb b/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution.ipynb
similarity index 90%
rename from f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution_Oliphant.ipynb
rename to f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution.ipynb
index 7c5ad1d..c4c97c8 100644
--- a/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution_Oliphant.ipynb
+++ b/f24/Louis_Lecture_Notes/23_Function_References/Lec_23_Function_References_Solution.ipynb
@@ -1,5 +1,12 @@
{
"cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Warmup"
+ ]
+ },
{
"cell_type": "code",
"execution_count": 1,
@@ -67,7 +74,7 @@
},
{
"cell_type": "code",
- "execution_count": 2,
+ "execution_count": 3,
"metadata": {},
"outputs": [
{
@@ -76,7 +83,7 @@
"16807"
]
},
- "execution_count": 2,
+ "execution_count": 3,
"metadata": {},
"output_type": "execute_result"
}
@@ -87,7 +94,7 @@
"def mystery(a, b): \n",
"# precondition: assume a > 0 and b > 0\n",
" if b == 1: \n",
- " return a;\n",
+ " return a\n",
" return a * mystery( a, b - 1 )\n",
"\n",
"# make a function call here\n",
@@ -95,18 +102,23 @@
"\n",
"#Q: What would be the result if we call\n",
"#. mystery(-3, -1) ??\n",
- "# If b starts at -1, and we subtract 1 each time we call a mystery, it will never == 1\n"
+ "# If b starts at -1, and we subtract 1 each time we call a mystery,\n",
+ "# it will never == 1\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
- "## Lecture 23: Functions are Objects!\n",
+ "# Functions are Objects!\n",
+ "\n",
+ "## Reading\n",
"\n",
- "As we have learned previously, all variables in Python are stored as objects.\n",
+ "- [Python for Everybody, 10.8](https://runestone.academy/ns/books/published/py4e-int/dictionaries/toctree.html)\n",
"\n",
- "This is also true for functions, and it gives us more power as programmers.\n",
+ "As we have learned previously, all variables contain references to objects.\n",
+ "\n",
+ "This is also true for function names, and it gives us more power as programmers.\n",
"\n",
"**Learning Objectives:**\n",
"\n",
@@ -118,18 +130,16 @@
},
{
"cell_type": "code",
- "execution_count": 3,
+ "execution_count": 4,
"metadata": {},
"outputs": [
{
- "data": {
- "text/plain": [
- "3"
- ]
- },
- "execution_count": 3,
- "metadata": {},
- "output_type": "execute_result"
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "3\n",
+ "3\n"
+ ]
}
],
"source": [
@@ -137,19 +147,20 @@
"# try this in Python Tutor\n",
"\n",
"x = [1,2,3]\n",
- "y = x\n",
+ "y = x # y holds a reference to the same object as x\n",
"\n",
- "def f(some_list): # what is f? its a function but also an object\n",
+ "def f(some_list): # f is the name of the function\n",
" return some_list[-1]\n",
"\n",
- "z = f(y) # z stores the result of a call to f\n",
+ "z = f(y) # z stores the result of a call to f\n",
"\n",
- "g = f # what is g? it is a reference to an object that is a function\n",
+ "g = f # g holds a reference to the same function as f\n",
"\n",
- "# TODO: similar to line 10, store the result of a call to g\n",
+ "# TODO: similar to calling f() and storing the result in z, but now call g and store the results in z2\n",
+ "z2 = g(y)\n",
"\n",
- "w = g(x) # calls the same function\n",
- "w"
+ "print(z)\n",
+ "print(z2)"
]
},
{
@@ -180,7 +191,7 @@
},
{
"cell_type": "code",
- "execution_count": 4,
+ "execution_count": 5,
"metadata": {},
"outputs": [
{
@@ -190,16 +201,16 @@
"tap tap tap\n",
"tap tap tap\n",
"tap tap tap\n",
- "churn churn churn\n",
- "churn churn churn\n",
- "churn churn churn\n",
- "churn churn churn\n",
- "churn churn churn\n"
+ "turn turn turn\n",
+ "turn turn turn\n",
+ "turn turn turn\n",
+ "turn turn turn\n",
+ "turn turn turn\n"
]
}
],
"source": [
- "# function references can be passed as arguments ...Wow!\n",
+ "# function references can be passed as arguments ... Wow!\n",
"\n",
"# first: try this in Python Tutor\n",
"\n",
@@ -209,7 +220,7 @@
"# then on your own: define a function called screwdriver\n",
"\n",
"def screwdriver():\n",
- " print(\"churn churn churn\")\n",
+ " print(\"turn turn turn\")\n",
"\n",
"def call_n_times(f, n):\n",
" for i in range(n):\n",
@@ -218,8 +229,7 @@
"call_n_times(hammer, 3)\n",
"\n",
"# then on your own: invoke call_n_times with screwdriver and 5 as arguments\n",
- "\n",
- "call_n_times(screwdriver, 5)\n"
+ "call_n_times(screwdriver,5)"
]
},
{
@@ -250,12 +260,12 @@
"source": [
"### Review: NamedTuples\n",
"\n",
- "We create a namedtuple `Point` with named attributes `x` and `y`. We then create lists of points we want to calculate distances between"
+ "We create a namedtuple `Point` with named attributes `x` and `y`. We then create lists of points we want to calculate distances between."
]
},
{
"cell_type": "code",
- "execution_count": 5,
+ "execution_count": 6,
"metadata": {},
"outputs": [],
"source": [
@@ -266,13 +276,17 @@
"left_points = [\n",
" Point(0, 0),\n",
" Point(3, 3),\n",
- " Point(2, 2)\n",
+ " Point(2, 2),\n",
+ " # TODO: Add another point!\n",
+ " Point(1, 1)\n",
"]\n",
"\n",
"right_points = [\n",
" Point(5, 5),\n",
" Point(0, 3),\n",
- " Point(2, 2)\n",
+ " Point(2, 2),\n",
+ " # TODO: Add another point!\n",
+ " Point(0, 0)\n",
"]"
]
},
@@ -289,26 +303,34 @@
"source": [
"We already did the math behind `manhattan_distance` and `euclidean_distance` for you!\n",
"\n",
- "**Hint:** `distance_algo` should be a reference to a function that calculates distance between two points.\n",
+ "Finish writing the `calculate_distances()` function, which should go over every point in `left_point`\n",
+ "and print the point, the matching point in `right_point` and the distance between them.\n",
+ "\n",
+ "**Hint:** The `distance_algo` parameter should be a reference to a function that calculates the distance between two points.\n",
+ "\n",
"\n",
"Then, call calculate_distances measuring first in manhattan_distance, then euclidean_distance."
]
},
{
"cell_type": "code",
- "execution_count": 6,
+ "execution_count": 10,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
- "10\n",
- "3\n",
- "0\n",
- "7.0710678118654755\n",
- "3.0\n",
- "0.0\n"
+ "MANHATTAN DISTANCE\n",
+ "Point(x=0, y=0) Point(x=5, y=5) 10\n",
+ "Point(x=3, y=3) Point(x=0, y=3) 3\n",
+ "Point(x=2, y=2) Point(x=2, y=2) 0\n",
+ "Point(x=1, y=1) Point(x=0, y=0) 2\n",
+ "EUCLIDEAN DISTANCE\n",
+ "Point(x=0, y=0) Point(x=5, y=5) 7.0710678118654755\n",
+ "Point(x=3, y=3) Point(x=0, y=3) 3.0\n",
+ "Point(x=2, y=2) Point(x=2, y=2) 0.0\n",
+ "Point(x=1, y=1) Point(x=0, y=0) 1.4142135623730951\n"
]
}
],
@@ -325,13 +347,18 @@
" dist_y = (point1.y - point2.y) ** 2\n",
" return math.sqrt(dist_x + dist_y)\n",
"\n",
+ "# TODO: Complete this function!\n",
"def calculate_distances(distance_algo):\n",
" for i in range(len(left_points)):\n",
" left_point = left_points[i]\n",
" right_point = right_points[i]\n",
- " print(distance_algo(left_point, right_point))\n",
+ " print(left_point, right_point, distance_algo(left_point, right_point))\n",
"\n",
+ "# TODO: Calculate the distance between the points using manhattan distance\n",
+ "# TODO: Calculate the distance between the points using euclidean distance\n",
+ "print(\"MANHATTAN DISTANCE\")\n",
"calculate_distances(manhattan_distance)\n",
+ "print(\"EUCLIDEAN DISTANCE\")\n",
"calculate_distances(euclidean_distance)"
]
},
@@ -339,42 +366,91 @@
"cell_type": "markdown",
"metadata": {},
"source": [
- "### Explain the default use of sorted() on lists of tuples, and on dictionaries.\n"
+ "### Explain the default use of sorted() on lists of tuples, and on dictionaries.\n",
+ "\n",
+ "The `sort()` method and the `sorted()` function have two optional arguments, `key` and `reverse`. These\n",
+ "arguments control how the list will be sorted. The `reverse` argument defaults to `False`, but if you set\n",
+ "it to true then the list will be sorted in reverse order.\n",
+ "\n",
+ "Take a look at the help function for `sorted()` in the cell below then try sorting the `populations` \n",
+ "list, first in sorted order then in reverse sorted order."
]
},
{
"cell_type": "code",
- "execution_count": 7,
+ "execution_count": 11,
"metadata": {},
"outputs": [
{
- "data": {
- "text/plain": [
- "[99, 77, 55, 33, 22]"
- ]
- },
- "execution_count": 7,
- "metadata": {},
- "output_type": "execute_result"
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Help on built-in function sorted in module builtins:\n",
+ "\n",
+ "sorted(iterable, /, *, key=None, reverse=False)\n",
+ " Return a new list containing all items from the iterable in ascending order.\n",
+ " \n",
+ " A custom key function can be supplied to customize the sort order, and the\n",
+ " reverse flag can be set to request the result in descending order.\n",
+ "\n"
+ ]
+ }
+ ],
+ "source": [
+ "# print out the help for the sorted function and read about the reverse and key parameters\n",
+ "help(sorted)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 12,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "[22, 33, 55, 77, 99]\n",
+ "[99, 77, 55, 33, 22]\n"
+ ]
}
],
"source": [
- "# first... did you know that sort/sorted takes a 2nd argument called reverse?\n",
- "\n",
"populations = [55, 77, 33, 99, 22]\n",
- "# TODO: sort populations in reverse\n",
- "sorted(populations, reverse=True)"
+ "# TODO: sort populations then sort again in reverse order\n",
+ "print(sorted(populations))\n",
+ "print(sorted(populations,reverse=True))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## The `key` parameter in `sort()` and `sorted()`\n",
+ "\n",
+ "The `key` parameter is a function that can be used to customize how the list will be sorted.\n",
+ "This is especially useful when sorting things where it is not clear what their order should be or if you\n",
+ "want to change the default soriting behavior. The function that should be passed to `key` takes as input\n",
+ "one item at a time from the list and it should return something that the `sort()` or `sorted()`\n",
+ "function does know how to sort, like a string or a number.\n",
+ "\n",
+ "For example, take a look at the `owhockey_badgers` list below. Notice that the list contains tuples.\n",
+ "If you were to call `sort()` or `sorted()` on this list, the default behavior would be to sort using the first\n",
+ "item in each tuple, then the second, and so on.\n",
+ "\n",
+ "Run the code in the cell below to see the default sorting behavior."
]
},
{
"cell_type": "code",
- "execution_count": 8,
+ "execution_count": 13,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
- "[('Abbey', 'Roque', 24),\n",
+ "[('Abbey', 'Roques', 27),\n",
+ " ('Abbey', 'Roquet', 24),\n",
" ('Alex', 'Cavalenni', 30),\n",
" ('Amanda', 'Kessel', 30),\n",
" ('Brianna', 'Decker', 30),\n",
@@ -382,7 +458,7 @@
" ('Hillary', 'Knight', 32)]"
]
},
- "execution_count": 8,
+ "execution_count": 13,
"metadata": {},
"output_type": "execute_result"
}
@@ -396,7 +472,8 @@
" (\"Amanda\", \"Kessel\", 30),\n",
" (\"Alex\", \"Cavalenni\", 30), \n",
" (\"Caroline\", \"Harvey\", 19),\n",
- " (\"Abbey\", \"Roque\", 24)\n",
+ " (\"Abbey\", \"Roquet\", 24),\n",
+ " (\"Abbey\", \"Roques\", 27)\n",
" ]\n",
"\n",
"\n",
@@ -405,18 +482,29 @@
"# what did this make? How was it sorted? "
]
},
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "If you want to have the list sorted by the age of each player, then you need to tell\n",
+ "the sorting algorithm which item to sort by. You can create a function that takes\n",
+ "as input a single item from the list and returns the value that you want to be used\n",
+ "when sorting. In the cell below three such functions are created to return the\n",
+ "item from the tuple that you want to use when sorting the list."
+ ]
+ },
{
"cell_type": "code",
- "execution_count": 9,
+ "execution_count": 14,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
- "'Gurmail'"
+ "'Mike'"
]
},
- "execution_count": 9,
+ "execution_count": 14,
"metadata": {},
"output_type": "execute_result"
}
@@ -432,28 +520,37 @@
"def select2(some_tuple):\n",
" return some_tuple[2]\n",
"\n",
- "# Test these functions on the tuple (\"Mike\", \"Gurmail\", \"Cole\")\n",
- "my_tuple = (\"Mike\", \"Gurmail\", \"Cole\")\n",
- "select1(my_tuple)\n"
+ "# TODO: Test these functions on the tuple (\"Mike\", \"Louis\", \"Cole\")\n",
+ "test_tuple = (\"Mike\", \"Louis\", \"Cole\")\n",
+ "\n",
+ "select0(test_tuple)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Try using each of these select functions as the key when sorting the `owhockey_badgers` list."
]
},
{
"cell_type": "code",
- "execution_count": 10,
+ "execution_count": 15,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[('Caroline', 'Harvey', 19),\n",
- " ('Abbey', 'Roque', 24),\n",
+ " ('Abbey', 'Roquet', 24),\n",
+ " ('Abbey', 'Roques', 27),\n",
" ('Brianna', 'Decker', 30),\n",
" ('Amanda', 'Kessel', 30),\n",
" ('Alex', 'Cavalenni', 30),\n",
" ('Hillary', 'Knight', 32)]"
]
},
- "execution_count": 10,
+ "execution_count": 15,
"metadata": {},
"output_type": "execute_result"
}
@@ -462,271 +559,218 @@
"# call sorted using the 'key' argument \n",
"# sort and sorted can take a parameter named key\n",
"# key is a reference to a function!\n",
+ "# TODO: Try sorting by first name, last name, and age\n",
"\n",
"sorted(owhockey_badgers, key=select2)"
]
},
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "The default behavior when sorting a list of dictionaries, is to fail. Python does not\n",
+ "know how to sort dictionaries. In this case you must have a `key` function that can extract\n",
+ "the right value so Python will know how to sort. Try sorting without passing a key function\n",
+ "to sort the list of dictionaries then write a function to get the `age` key from the dictionary\n",
+ "and use that when sorting."
+ ]
+ },
{
"cell_type": "code",
- "execution_count": 11,
+ "execution_count": 16,
"metadata": {},
"outputs": [
{
- "data": {
- "text/plain": [
- "[('Alex', 'Cavalenni', 30),\n",
- " ('Brianna', 'Decker', 30),\n",
- " ('Caroline', 'Harvey', 19),\n",
- " ('Amanda', 'Kessel', 30),\n",
- " ('Hillary', 'Knight', 32),\n",
- " ('Abbey', 'Roque', 24)]"
- ]
- },
- "execution_count": 11,
- "metadata": {},
- "output_type": "execute_result"
+ "ename": "TypeError",
+ "evalue": "'<' not supported between instances of 'dict' and 'dict'",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mTypeError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[16], line 10\u001b[0m\n\u001b[1;32m 1\u001b[0m people \u001b[38;5;241m=\u001b[39m [\n\u001b[1;32m 2\u001b[0m {\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mfirst\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mLouis\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mlast\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mOliphant\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mage\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;241m53\u001b[39m},\n\u001b[1;32m 3\u001b[0m {\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mfirst\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mBecky\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mlast\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mBrown\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mage\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;241m52\u001b[39m},\n\u001b[1;32m 4\u001b[0m {\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mfirst\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mSam\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mlast\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mLuna-Nelson\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mage\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;241m26\u001b[39m},\n\u001b[1;32m 5\u001b[0m {\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mfirst\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mSally\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mlast\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mFields\u001b[39m\u001b[38;5;124m'\u001b[39m, \u001b[38;5;124m'\u001b[39m\u001b[38;5;124mage\u001b[39m\u001b[38;5;124m'\u001b[39m:\u001b[38;5;241m47\u001b[39m}\n\u001b[1;32m 6\u001b[0m ]\n\u001b[1;32m 8\u001b[0m \u001b[38;5;66;03m##TODO: first try sorting without passing a function for the key parameter\u001b[39;00m\n\u001b[0;32m---> 10\u001b[0m \u001b[38;5;28;43msorted\u001b[39;49m\u001b[43m(\u001b[49m\u001b[43mpeople\u001b[49m\u001b[43m)\u001b[49m\n",
+ "\u001b[0;31mTypeError\u001b[0m: '<' not supported between instances of 'dict' and 'dict'"
+ ]
}
],
"source": [
- "# sort the list of tuples based on the last name\n",
- "sorted(owhockey_badgers, key=select1)"
+ "people = [\n",
+ " {'first':'Louis', 'last':'Oliphant', 'age':53},\n",
+ " {'first':'Becky', 'last':'Brown', 'age':52},\n",
+ " {'first':'Sam', 'last':'Luna-Nelson', 'age':26},\n",
+ " {'first':'Sally', 'last':'Fields', 'age':47}\n",
+ "]\n",
+ "\n",
+ "##TODO: first try sorting without passing a function for the key parameter\n",
+ "\n",
+ "sorted(people)\n",
+ " "
]
},
{
"cell_type": "code",
- "execution_count": 12,
+ "execution_count": 17,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
- "[('Caroline', 'Harvey', 19),\n",
- " ('Abbey', 'Roque', 24),\n",
- " ('Brianna', 'Decker', 30),\n",
- " ('Amanda', 'Kessel', 30),\n",
- " ('Alex', 'Cavalenni', 30),\n",
- " ('Hillary', 'Knight', 32)]"
+ "[{'first': 'Sam', 'last': 'Luna-Nelson', 'age': 26},\n",
+ " {'first': 'Sally', 'last': 'Fields', 'age': 47},\n",
+ " {'first': 'Becky', 'last': 'Brown', 'age': 52},\n",
+ " {'first': 'Louis', 'last': 'Oliphant', 'age': 53}]"
]
},
- "execution_count": 12,
+ "execution_count": 17,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
- "# sort the list of tuples based on the age\n",
- "sorted(owhockey_badgers, key=select2)"
+ "\n",
+ "##TODO: finish the get_age() function that takes a single dictionary and returns\n",
+ "## the age key from the dictionary.\n",
+ "\n",
+ "def get_age(d):\n",
+ " #return the 'age' key\n",
+ " return d['age']\n",
+ "\n",
+ "##TODO: use the get_age function as the key and try sorting again\n",
+ "\n",
+ "sorted(people, key=get_age)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
- "### Using `lambda`\n",
+ "### Using `lambda` functions\n",
"- `lambda` functions are a way to abstract a function reference\n",
"- lambdas are simple functions with:\n",
" - multiple possible parameters\n",
- " - single expression line as the function body\n",
+ " - single **expression** line as the function body\n",
"- lambdas are useful abstractions for:\n",
" - mathematical functions\n",
" - lookup operations\n",
"- lambdas are often associated with a collection of values within a list\n",
- "- Syntax: \n",
+ "- Syntax:\n",
+ " \n",
"```python \n",
"lambda parameters: expression\n",
- "```\n"
+ "```\n",
+ "\n",
+ "Here are some examples of creating a function using this lambda notation. Note that the variable holds the *function*. Below each creation of the function is a call to the function.\n",
+ "\n",
+ "```python\n",
+ "f = lambda a : a + 10\n",
+ "print(f(1))\n",
+ "```\n",
+ "```\n",
+ "11\n",
+ "```\n",
+ "```python\n",
+ "f2 = lambda a, b : a * b\n",
+ "print(f2(3,4))\n",
+ "```\n",
+ "```\n",
+ "12\n",
+ "```\n",
+ "\n",
+ "Let's use a lambda function to sort the `owhockey_badgers` tuple by the age (i.e. the last field)."
]
},
{
"cell_type": "code",
- "execution_count": 13,
+ "execution_count": 18,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[('Caroline', 'Harvey', 19),\n",
- " ('Abbey', 'Roque', 24),\n",
+ " ('Abbey', 'Roquet', 24),\n",
+ " ('Abbey', 'Roques', 27),\n",
" ('Brianna', 'Decker', 30),\n",
" ('Amanda', 'Kessel', 30),\n",
" ('Alex', 'Cavalenni', 30),\n",
" ('Hillary', 'Knight', 32)]"
]
},
- "execution_count": 13,
+ "execution_count": 18,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
- "# sorting part 3....using lambdas\n",
- "\n",
- "'''\n",
- "def no_name(each_tuple):\n",
- " return each_tuple[-1]\n",
- "'''\n",
"\n",
"sorted(owhockey_badgers, key = lambda each_tuple : each_tuple[-1])\n",
"\n",
- "# read the lambda as: my no-name function has each_tuple as a parameter\n",
+ "# read the lambda as: my no-name function has each_tuple from owhockey_badgers as a parameter\n",
"# and returns each_tuple[-1] (the last element)\n",
"# the variable 'each_tuple' is like a function parameter"
]
},
{
"cell_type": "code",
- "execution_count": 14,
- "metadata": {},
- "outputs": [
- {
- "data": {
- "text/plain": [
- "[('Alex', 'Cavalenni', 30),\n",
- " ('Abbey', 'Roque', 24),\n",
- " ('Amanda', 'Kessel', 30),\n",
- " ('Hillary', 'Knight', 32),\n",
- " ('Brianna', 'Decker', 30),\n",
- " ('Caroline', 'Harvey', 19)]"
- ]
- },
- "execution_count": 14,
- "metadata": {},
- "output_type": "execute_result"
- }
- ],
- "source": [
- "# TODO: sort the list by the length of the first name\n",
- "'''\n",
- "def no_name(x):\n",
- " return len(x[0])\n",
- "'''\n",
- "sorted(owhockey_badgers, key = lambda x : len(x[0]))"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 15,
- "metadata": {},
- "outputs": [
- {
- "data": {
- "text/plain": [
- "[('Abbey', 'Roque', 24),\n",
- " ('Amanda', 'Kessel', 30),\n",
- " ('Hillary', 'Knight', 32),\n",
- " ('Brianna', 'Decker', 30),\n",
- " ('Alex', 'Cavalenni', 30),\n",
- " ('Caroline', 'Harvey', 19)]"
- ]
- },
- "execution_count": 15,
- "metadata": {},
- "output_type": "execute_result"
- }
- ],
- "source": [
- "# TODO: Sort the list by the length of their full name\n",
- "'''\n",
- "def no_name(player):\n",
- " return len(player[0]) + len(player[1])\n",
- "'''\n",
- "sorted(owhockey_badgers, key = lambda player : len(player[0]) + len(player[1]))"
- ]
- },
- {
- "cell_type": "markdown",
- "metadata": {},
- "source": [
- "### OK, I can sort a list of tuples....what about a list of dictionaries?"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 16,
+ "execution_count": 19,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
- "[{'name': 'Calvin', 'year': 2000},\n",
- " {'name': 'Blanc', 'year': 1990, 'speed': 250},\n",
- " {'name': 'Alexandria', 'year': 1980, 'speed': 100}]"
+ "[{'first': 'Becky', 'last': 'Brown', 'age': 52},\n",
+ " {'first': 'Sally', 'last': 'Fields', 'age': 47},\n",
+ " {'first': 'Sam', 'last': 'Luna-Nelson', 'age': 26},\n",
+ " {'first': 'Louis', 'last': 'Oliphant', 'age': 53}]"
]
},
- "execution_count": 16,
+ "execution_count": 19,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
+ "# TODO: sort the people list of dictionaries by the last name\n",
"\n",
- "hurricanes = [\n",
- " {\"name\": \"Calvin\", \"year\": 2000},\n",
- " {\"name\": \"Alexandria\", \"year\": 1980, \"speed\": 100},\n",
- " {\"name\": \"Blanc\", \"year\": 1990, \"speed\": 250},\n",
- "]\n",
- "\n",
- "# call sorted on hurricanes and use a lambda expression to grab the year\n",
- "sorted(hurricanes, key = lambda d : d[\"year\"], reverse=True)\n"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 17,
- "metadata": {},
- "outputs": [
- {
- "data": {
- "text/plain": [
- "[{'name': 'Alexandria', 'year': 1980, 'speed': 100},\n",
- " {'name': 'Blanc', 'year': 1990, 'speed': 250},\n",
- " {'name': 'Calvin', 'year': 2000}]"
- ]
- },
- "execution_count": 17,
- "metadata": {},
- "output_type": "execute_result"
- }
- ],
- "source": [
- "# sort hurricanes alphabetically by name\n",
- "# for you to do on your own...see the above example\n",
- "sorted(hurricanes, key = lambda d : d[\"name\"])"
+ "sorted(people, key = lambda p : p['last'])"
]
},
{
"cell_type": "code",
- "execution_count": 18,
+ "execution_count": 21,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
- "[{'name': 'Calvin', 'year': 2000},\n",
- " {'name': 'Alexandria', 'year': 1980, 'speed': 100},\n",
- " {'name': 'Blanc', 'year': 1990, 'speed': 250}]"
+ "[{'first': 'Becky', 'last': 'Brown', 'age': 52},\n",
+ " {'first': 'Sally', 'last': 'Fields', 'age': 47},\n",
+ " {'first': 'Louis', 'last': 'Oliphant', 'age': 53},\n",
+ " {'first': 'Sam', 'last': 'Luna-Nelson', 'age': 26}]"
]
},
- "execution_count": 18,
+ "execution_count": 21,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
- "# on your own, sort hurricanes by speed.....\n",
- "sorted(hurricanes, key = lambda d : d.get(\"speed\", 0))"
+ "# TODO: Sort the people list of dictionaries by the LENGTH of their last name\n",
+ "\n",
+ "sorted(people, key = lambda p : len(p['last']))\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
- "### This is all great, but what I'd really like to do is to sort dictionaries!\n"
+ "### This is all great, but what I'd really like to do is to sort dictionaries!\n",
+ "\n",
+ "From Python 3.7 onwards, the standard dict type maintains insertion order by default ([see here](https://mail.python.org/pipermail/python-dev/2017-December/151283.html)), so a dictionary could be ordered, but what happens if you try and sort a dictionary?"
]
},
{
"cell_type": "code",
- "execution_count": 19,
+ "execution_count": 22,
"metadata": {},
"outputs": [
{
@@ -735,7 +779,7 @@
"['ala mode', 'cookie', 'donut', 'hot dog', 'loaf', 'milk', 'pie']"
]
},
- "execution_count": 19,
+ "execution_count": 22,
"metadata": {},
"output_type": "execute_result"
}
@@ -750,12 +794,12 @@
" 'hot dog': 4.99}\n",
"\n",
"# sorted (dict) returns a list of the keys sorted\n",
- "sorted(menu)\n"
+ "sorted(menu)"
]
},
{
"cell_type": "code",
- "execution_count": 20,
+ "execution_count": 23,
"metadata": {},
"outputs": [
{
@@ -764,7 +808,7 @@
"dict_items([('pie', 3.95), ('ala mode', 1.5), ('donut', 1.25), ('cookie', 0.79), ('milk', 1.65), ('loaf', 5.99), ('hot dog', 4.99)])"
]
},
- "execution_count": 20,
+ "execution_count": 23,
"metadata": {},
"output_type": "execute_result"
}
@@ -776,7 +820,7 @@
},
{
"cell_type": "code",
- "execution_count": 21,
+ "execution_count": 24,
"metadata": {},
"outputs": [
{
@@ -791,7 +835,7 @@
" ('pie', 3.95)]"
]
},
- "execution_count": 21,
+ "execution_count": 24,
"metadata": {},
"output_type": "execute_result"
}
@@ -801,12 +845,12 @@
"\n",
"# let's sort menu.items() the same way we sorted a list of tuples\n",
"\n",
- "sorted(menu.items(), key = lambda t : t[0] ) # set the sorting key to a lambda expressoin"
+ "sorted(menu.items(), key = lambda t : t[0] ) # set the sorting key to a lambda expression"
]
},
{
"cell_type": "code",
- "execution_count": 22,
+ "execution_count": 25,
"metadata": {},
"outputs": [
{
@@ -821,19 +865,19 @@
" 'pie': 3.95}"
]
},
- "execution_count": 22,
+ "execution_count": 25,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# now let's turn this list of tuples into a dict\n",
- "dict(sorted(menu.items(), key=lambda thing: thing[0]))"
+ "dict(sorted(menu.items(), key = lambda t : t[0]))"
]
},
{
"cell_type": "code",
- "execution_count": 23,
+ "execution_count": 26,
"metadata": {},
"outputs": [
{
@@ -848,41 +892,14 @@
" 'loaf': 5.99}"
]
},
- "execution_count": 23,
+ "execution_count": 26,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# can you change the previous code to sort by price? \n",
- "dict(sorted(menu.items(), key=lambda thing: thing[1]))"
- ]
- },
- {
- "cell_type": "code",
- "execution_count": 24,
- "metadata": {},
- "outputs": [
- {
- "data": {
- "text/plain": [
- "{'pie': 3.95,\n",
- " 'milk': 1.65,\n",
- " 'loaf': 5.99,\n",
- " 'donut': 1.25,\n",
- " 'cookie': 0.79,\n",
- " 'hot dog': 4.99,\n",
- " 'ala mode': 1.5}"
- ]
- },
- "execution_count": 24,
- "metadata": {},
- "output_type": "execute_result"
- }
- ],
- "source": [
- "# can you sort the dictionary by the length of the name? \n",
- "dict(sorted(menu.items(), key=lambda thing: len(thing[0])))"
+ "dict(sorted(menu.items(), key = lambda t : t[1]))"
]
},
{
@@ -894,19 +911,40 @@
},
{
"cell_type": "code",
- "execution_count": 25,
+ "execution_count": 30,
"metadata": {},
- "outputs": [],
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "[1, 2, 3, 4, 5, 6, 8]\n",
+ "[{'one': 2, 'two': 1}, {'one': 5, 'two': 8}, {'one': 7, 'two': 6}]\n",
+ "{'four': 43, 'one': 8, 'three': 12, 'two': 3}\n",
+ "{'two': 3, 'one': 8, 'three': 12, 'four': 43}\n"
+ ]
+ }
+ ],
"source": [
"# Practice sorting a list of tuples\n",
+ "print(sorted((5,3,4,6,2,1,8)))\n",
"\n",
"# Practice sorting a list of dictionaries \n",
- "\n",
+ "print(sorted([{'one':5,'two':8},{'one':2,'two':1},{'one':7,'two':6}],key=lambda p: p['one']))\n",
"# Practice sorting a dictionary by keys\n",
+ "print(dict(sorted({'one':8,'two':3,'three':12,'four':43}.items(),key=lambda t: t[0])))\n",
"\n",
"# Practice sorting a dictionary by values\n",
+ "print(dict(sorted({'one':8,'two':3,'three':12,'four':43}.items(),key=lambda t: t[1])))\n",
"\n"
]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": []
}
],
"metadata": {
@@ -925,7 +963,7 @@
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
- "version": "3.11.5"
+ "version": "3.10.12"
}
},
"nbformat": 4,
--
GitLab