{
"cells": [
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"data": {
"text/html": [
"\n",
" <iframe\n",
" width=\"640\"\n",
" height=\"390\"\n",
" src=\"https://www.youtube.com/embed/M_eYSuPKP3Y\"\n",
" frameborder=\"0\"\n",
" allowfullscreen\n",
" ></iframe>\n",
" "
],
"text/plain": [
"<IPython.lib.display.YouTubeVideo at 0x104a05b70>"
]
},
"execution_count": 3,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"from IPython.display import YouTubeVideo\n",
"YouTubeVideo(\"M_eYSuPKP3Y\",width=\"640\",height=\"390\")"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<pre>\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"\n",
"</pre>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<img src=\"https://raw.githubusercontent.com/profjsb/python-bootcamp/master/Lectures/02_AdvancedDataStructures/slide1.png\" width=\"90%\">\n",
"UC Berkeley Python Bootcamp (c) J. Bloom All Rights Reserved"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"## There are four main types of collections of data (\"Sequence objects\") ##\n",
"\n",
"\t•\tLists: a mutable array of data\n",
"\t•\tTuples: ordered, immutable list\n",
"\t•\tSets: unordered collection of unique elements\n",
"\t•\tDictionaries: keyword/value lookup\n",
"\n",
"The value in each element can be whatever (type) you want.\n",
"> string is actually a sequence object"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### Tuple ###\n",
"denoted with parentheses"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"t = (12,-1)\n",
"print(type(t))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"print(isinstance(t,tuple))\n",
"print(len(t))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"t = (12,\"monty\",True,-1.23e6)\n",
"print(t[1])"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"print(t[-1])"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"t[-2:] # get the last two elements, return as a tuple"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"x = (True) ; print(type(x))\n",
"x = (True,) ; print(type(x))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"type(()), len(())"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "-"
}
},
"outputs": [],
"source": [
"type((,))"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"single-element tuples look like `(element,)`"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"cannot change a tuple\n",
"but you can create new one with concatenation"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"t[2] = False"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"type((1,\"spam\",\"eggs\", None))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"t[0:2], False, t[3:]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"## the above it \n",
"## not what we wanted... need to concatenate\n",
"t[0:2] + False + t[3:]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"y = t[0:2] + (False,) + t[3:] ; print(y)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"t*2"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### List ###\n",
"#### denoted with a brackets ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = [1,2,3] ; print(len(v), type(v))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v[0:2]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = [\"eggs\",\"spam\",-1,(\"monty\",\"python\"),[-1.2,-3.5]]\n",
"len(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v[0] =\"green egg\"\n",
"v[1] += \",love it.\"\n",
"v[-1]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"v[-1][1]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v[-1][1] = None ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = v[2:] ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# let's make a proto-array out of nested lists\n",
"vv = [ [1,2], [3,4] ]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(len(vv))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"determinant = vv[0][0]*vv[1][1] - vv[0][1]*vv[1][0]\n",
"print(determinant)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"the main point here: lists are **changeable** (\"mutable\")"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### lists can be extended & appended ###"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = [1,2,3]\n",
"v.append(4) \n",
"print(v)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"> Lists can be considered objects.\n",
"**Objects** are like animals: they know how to do stuff (like eat and sleep), they know how to interact with others (like make children), and they have characteristics (like height, weight).\n",
"\n",
"> \"Knowing how to do stuff\" with itself is called a method. In this case \"append\" is a method which, when invoked, is an action that changes the characteristics (the data vector of the list itself)."
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### List ###\n",
"#### lists can be extended, appended, and popped ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = [1,2,3]\n",
"v.append(4)\n",
"v.append([-5]) ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = v[:4]\n",
"w = ['elderberries', 'eggs']\n",
"v + w"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.extend(w) ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.pop()"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.pop(0) ; print(v) ## pop the first element"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"v.append(0)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"v = [\"hello\"] + v"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"print(v)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" * `.append()`: adds a new element\n",
" * `.extend()`: concatenates a list/element\n",
" * `.pop()`: remove an element"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"#### lists can be searched, sorted, & counted ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v = [1,3, 2, 3, 4, 1.3]\n",
"v.sort() ; print(v)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"If there isn't a natural way to compare elements, the sort will fail.\n",
"\n",
"`reverse` is a keyword of the `.sort()` method"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"import math\n",
"v = [1,3, 2, 3, 4, math.pi]\n",
"v.sort() ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.sort(reverse=True) ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"v.sort?"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"`.sort()` changes the the list in place "
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.index(4) ## lookup the index of the entry 4"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.index(3)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.count(3)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.insert(0,\"it's full of stars\") ; print(v)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"v.remove(3.0) ; print(v)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### IPython is your new best friend ##\n",
"\n",
"1. Type `v.` then the Tab button\n",
"\n",
"2. Type `v.re` then the Tab button\n",
"\n",
"3. Type `v.remove?`"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"## try it here"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": []
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### List ###\n",
"#### iteration ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"x = 1\n",
"a = ['cat', 'window', 'defenestrate']\n",
"for x in a:\n",
" print(x, len(x))\n",
" if x == \"cat\":\n",
" a.append(\"?\")\n",
"print(x)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"for i,x in enumerate(a):\n",
" print(i, x, len(x))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"b = enumerate(a)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"print(b.__next__())"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"for x in a:\n",
" print(x, end=',')"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"The syntax for iteration is... \n",
"\n",
" for variable_name in iterable:\n",
" # do something with variable_name"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"The `range()` function"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"x = list(range(4)) ; print(x)\n",
"total = 0\n",
"for val in range(4):\n",
" total += val\n",
" print(\"By adding \" + str(val) + \\\n",
" \" the total is now \" + str(total))"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"\n",
"`range`([`start`,] `stop`[, `step`])\n",
"→ list of integers"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"total = 0\n",
"for x in range(1,10,2):\n",
" total += x\n",
" print(\"By adding \" + str(x) + \\\n",
" \" the total is now \" + str(total))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"a = ['Mary', 'had', 'a', 'little', 'lamb']\n",
"for i in range(len(a)):\n",
" print(i, a[i])"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### Sets ###\n",
"#### denoted with a curly braces ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"{1,2,3,\"bingo\"}"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(type({1,2,3,\"bingo\"}))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(type({}))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(type(set()))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"set([\"spamIam\"])"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"sets have unique elements. They can be\n",
"compared, differenced, unionized, etc."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "slide"
}
},
"outputs": [],
"source": [
"a = set(\"sp\") ; b = set(\"am\"); print(a) ; print(b)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"c = set([\"m\",\"a\"])\n",
"c == b"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"\"p\" in a"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"\"ps\" in a"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q = set(\"spamIam\")\n",
"a.issubset(q)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"a | b"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q - (a | b)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q & (a | b)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"Like lists, we can use as (unordered) buckets\n",
"`.pop()` gives us a random element"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "slide"
}
},
"outputs": [],
"source": [
"# this is pretty volitile...wont be the same\n",
"# order on all machines\n",
"for i in q & (a | b):\n",
" print(i, end=' ') "
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q.remove(\"a\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q.pop()"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(q.pop())\n",
"print(q.pop())"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(q.pop())\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"print(q)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"q.pop()"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"## Dictionaries ##\n",
"denoted with a curly braces and colons"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"d = {\"favorite cat\": None, \"favorite spam\": \"all\"}"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"these are key: value, key: value, ..."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(d[\"favorite cat\"])\n",
"d[0] ## this is not a list and you dont have a keyword = 0"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"e = {\"favorite cat\": None, \"favorite spam\": \"all\", \\\n",
" 1: 'loneliest number'}\n",
"e[1] == 'loneliest number'"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"dictionaries are **UNORDERED**<sup>*</sup>. \n",
">You cannot assume that one key comes before or after another\n",
"\n",
"<sup>*</sup> you can use a special type of ordered dict if you really need it:\n",
"\n",
"https://docs.python.org/3.1/whatsnew/3.1.html#pep-372-ordered-dictionaries"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### 4 ways to make a Dictionary ###"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# number 1...you've seen this\n",
"d = {\"favorite cat\": None, \"favorite spam\": \"all\"}"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# number 2\n",
"d = dict(one = 1, two=2,cat = 'dog') ; print(d)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# number 3 ... just start filling in items/keys\n",
"d = {} # empty dictionary\n",
"d['cat'] = 'dog'\n",
"d['one'] = 1\n",
"d['two'] = 2\n",
"d"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# number 4... start with a list of tuples\n",
"mylist = [(\"cat\",\"dog\"), (\"one\",1),(\"two\",2)]\n",
"print(dict(mylist))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"dict(mylist) == d"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"list(d)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"#### Dictionaries: they can be complicated (in a good way) ####"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"d = {\"favorite cat\": None, \"favorite spam\": \"all\"}"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"d = {'favorites': {'cat': None, 'spam': 'all'}, \\\n",
" 'least favorite': {'cat': 'all', 'spam': None}}\n",
"print(d['least favorite']['cat'])"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"remember: the backslash (\\) allows you to across break lines. Not technically needed when defining a dictionary or list"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"phone_numbers = {'family': [('mom','642-2322'),('dad','534-2311')],\\\n",
" 'friends': [('Billy','652-2212')]}"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"for group_type in ['friends','family']:\n",
" print(\"Group\",group_type,\":\",sep=\" \")\n",
" for info in phone_numbers[group_type]:\n",
" print(\"\\t\",info[0],info[1],sep=\" \")"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# this will return a list, but you dont know in what order! \n",
"list(phone_numbers.keys())"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"list(phone_numbers.values())[-1]"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"`.keys()` and `.values()`: are called `methods` on dictionaries"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"for group_type in list(phone_numbers.keys()):\n",
" print(\"Group\",group_type,\":\",sep=\" \")\n",
" for info in phone_numbers[group_type]:\n",
" print(\"\\t\",info[0],info[1],sep=\" \")"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"we cannot ensure ordering here of the groups"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"groups = list(phone_numbers.keys())\n",
"groups.sort()\n",
"for group_type in groups:\n",
" print(\"Group\",group_type,\":\",sep=\" \")\n",
" for info in phone_numbers[group_type]:\n",
" print(\"\\t\",info[0],info[1],sep=\" \")"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"`.items()` is a handy method,\n",
"returning key,value pairs with each iteration"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"for group_type, vals in phone_numbers.items():\n",
" print(\"Group\",group_type,\":\",sep=\" \")\n",
" for info in vals:\n",
" print(\"\\t\",info[0],info[1],sep=\" \")"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"Some examples of getting values:"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"phone_numbers['co-workers']"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"'co-workers' in phone_numbers"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(phone_numbers.get('co-workers'))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "skip"
}
},
"outputs": [],
"source": [
"phone_numbers.get('friends') == phone_numbers['friends']"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Defaults in a `get`"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(phone_numbers.get('co-workers',\"all alone\"))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"phone_numbers.get?"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"#### setting values ####\n",
"\n",
"you can edit the values of keys and also `.pop()` & `del` to remove certain keys"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"\"BFFs\" in phone_numbers.keys()"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# add to the friends list\n",
"phone_numbers['friends'].append((\"Marsha\",\"232-1121\"))\n",
"print(phone_numbers)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"## billy's number changed\n",
"phone_numbers['friends'][0][1] = \"532-1521\""
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"phone_numbers['friends'][0] = (\"Billy\",\"532-1521\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"## I lost all my friends preparing for this Python class\n",
"phone_numbers['friends'] = [] # sets this to an empty list"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"## remove the friends key altogether\n",
"print(phone_numbers.pop('friends'))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(phone_numbers)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"del phone_numbers['family']"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(phone_numbers)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"`.update()` method is very handy, like `.append()` for lists"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"phone_numbers.update({\"friends\": [(\"Billy's Brother, Bob\", \"532-1521\")]})\n",
"print(phone_numbers)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"### Casting Back and Forth ###"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"a = [1,2,3,(\"b\",1),(\"b\",1)]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"b = tuple(a) ; print(b)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"print(list(b))"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"set(a)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"list(set(\"spam\"))"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"> casting only affects top-level structure, not the elements "
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "slide"
}
},
"source": [
"## List Comprehension ##\n",
"\n",
"You can create lists \"on the fly\" by asking simple questions of other iterateable data structures"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"example: I want a list of all numbers from 0 - 100 whose lowest two bits are both one (e.g., 3, 7, ...) but is not divisible by 11"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"mylist = []\n",
"for num in range(101):\n",
" if (num & 2) and (num & 1) and (num % 11 != 0.0):\n",
" mylist.append(num)\n",
"print(mylist)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"mylist=[num for num in range(101) if (num & 2) \\\n",
" and (num & 1) and (num % 11 != 0.0)]\n",
"print(mylist)"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
"example: I want a list of all mesons whose masses are between 100 and 1000 MeV"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"particles = \\\n",
"[{\"name\":\"π+\" ,\"mass\": 139.57018}, {\"name\":\"π0\" ,\"mass\": 134.9766}, \n",
" {\"name\":\"η5\" ,\"mass\": 47.853}, {\"name\":\"η′(958)\",\"mass\": 957.78}, \n",
" {\"name\":\"ηc(1S)\", \"mass\": 2980.5}, {\"name\": \"ηb(1S)\",\"mass\": 9388.9}, \n",
" {\"name\":\"K+\", \"mass\": 493.677}, {\"name\":\"K0\" ,\"mass\": 497.614}, \n",
" {\"name\":\"K0S\" ,\"mass\": 497.614}, {\"name\":\"K0L\" ,\"mass\": 497.614},\n",
" {\"name\":\"D+\" ,\"mass\": 1869.62}, {\"name\":\"D0\" ,\"mass\": 1864.84},\n",
" {\"name\":\"D+s\" ,\"mass\": 1968.49}, {\"name\":\"B+\" ,\"mass\": 5279.15},\n",
" {\"name\":\"B0\" ,\"mass\": 5279.5}, {\"name\":\"B0s\" ,\"mass\": 5366.3},\n",
" {\"name\":\"B+c\" ,\"mass\": 6277}]\n",
"\n",
"# data source: http://en.wikipedia.org/wiki/List_of_mesons\n",
"\n",
"my_mesons = [ (x['name'],x['mass']) for \\\n",
" x in particles if x['mass'] <= 1000.0 and x['mass'] >= 100.0]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"# get the average\n",
"tot = 0.0\n",
"for x in my_mesons: tot += x[1]\n",
"print(\"The average meson mass in this range is \" + str(tot/len(my_mesons)) \\\n",
" + \" MeV/c^2.\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"print(\"The average meson mass in this range is \" + str(round(tot/len(my_mesons),2)) \\\n",
" + \" MeV/c^2.\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"my_mesons[0][0]"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": false,
"slideshow": {
"slide_type": "fragment"
}
},
"outputs": [],
"source": [
"bytes(my_mesons[0][0],encoding=\"utf-8\")"
]
},
{
"cell_type": "markdown",
"metadata": {
"slideshow": {
"slide_type": "fragment"
}
},
"source": [
" "
]
},
{
"cell_type": "markdown",
"metadata": {
"collapsed": true
},
"source": [
"## Breakout Session Work"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Consider the following data (file: `airline.py`):"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"# %load airline.py\n",
"airports = {\"DCA\": \"Washington, D.C.\", \"IAD\": \"Dulles\", \"LHR\": \"London-Heathrow\", \\\n",
" \"SVO\": \"Moscow\", \"CDA\": \"Chicago-Midway\", \"SBA\": \"Santa Barbara\", \"LAX\": \"Los Angeles\",\\\n",
" \"JFK\": \"New York City\", \"MIA\": \"Miami\", \"AUM\": \"Austin, Minnesota\"}\n",
" \n",
"# airline, number, heading to, gate, time (decimal hours) \n",
"flights = [(\"Southwest\",145,\"DCA\",1,6.00),(\"United\",31,\"IAD\",1,7.1),(\"United\",302,\"LHR\",5,6.5),\\\n",
" (\"Aeroflot\",34,\"SVO\",5,9.00),(\"Southwest\",146,\"CDA\",1,9.60), (\"United\",46,\"LAX\",5,6.5),\\\n",
" (\"Southwest\",23,\"SBA\",6,12.5),(\"United\",2,\"LAX\",10,12.5),(\"Southwest\",59,\"LAX\",11,14.5),\\\n",
" (\"American\", 1,\"JFK\",12,11.3),(\"USAirways\", 8,\"MIA\",20,13.1),(\"United\",2032,\"MIA\",21,15.1),\\\n",
" (\"SpamAir\",1,\"AUM\",42,14.4)]\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### 1. print out a schedule organized by airline:\n",
"\n",
"<pre>\n",
"Flight Destination Gate Time\n",
"--------------------------------------------------\n",
"Aeroflot 34 Moscow \t5 9.0\n",
"American 1 New York City \t12 11.3\n",
"Southwest 23 Santa Barbara \t6 12.5\n",
"Southwest 59 Los Angeles \t11 14.5\n",
"...\n",
"</pre>\n",
"\n",
"### 2. print out a schedule organized by time\n",
"\n",
"*hint: you'll need to do a manual sorting on the last element of each flight element, before beginning the printing loop*"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<img id=\"embedLinkJPG\" src=\"http://i3.cpcache.com/product/51620593/will_code_python_for_food_black_tshirt.jpg?color=Black&height=460&width=460&qv=90\" alt=\"Will Code Python For Food Black T-Shirt\" width=\"460\" height=\"460\">"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": []
}
],
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"kernelspec": {
"display_name": "Python 3",
"language": "python",
"name": "py3k"
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"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
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"file_extension": ".py",
"mimetype": "text/x-python",
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