|
| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "attachments": {}, |
| 5 | + "cell_type": "markdown", |
| 6 | + "metadata": {}, |
| 7 | + "source": [ |
| 8 | + "# Dictionaries\n", |
| 9 | + "\n", |
| 10 | + "## Its an unordered collection of data values, used to store data values like a map, which unlike other Data Types that hold only a single value as an element, Dictionary holds key:value pair. Key-value is provided in the dictionary to make it more optimized. " |
| 11 | + ] |
| 12 | + }, |
| 13 | + { |
| 14 | + "cell_type": "code", |
| 15 | + "execution_count": 6, |
| 16 | + "metadata": {}, |
| 17 | + "outputs": [ |
| 18 | + { |
| 19 | + "name": "stdout", |
| 20 | + "output_type": "stream", |
| 21 | + "text": [ |
| 22 | + "{}\n", |
| 23 | + "0\n", |
| 24 | + "<class 'dict'>\n" |
| 25 | + ] |
| 26 | + } |
| 27 | + ], |
| 28 | + "source": [ |
| 29 | + "## Empty Dictionaries\n", |
| 30 | + "emptyDict = {}\n", |
| 31 | + "print(emptyDict)\n", |
| 32 | + "print(len(emptyDict))\n", |
| 33 | + "print(type(emptyDict))" |
| 34 | + ] |
| 35 | + }, |
| 36 | + { |
| 37 | + "cell_type": "code", |
| 38 | + "execution_count": 12, |
| 39 | + "metadata": {}, |
| 40 | + "outputs": [ |
| 41 | + { |
| 42 | + "name": "stdout", |
| 43 | + "output_type": "stream", |
| 44 | + "text": [ |
| 45 | + "42\n", |
| 46 | + "1\n" |
| 47 | + ] |
| 48 | + } |
| 49 | + ], |
| 50 | + "source": [ |
| 51 | + "dict = {'foo' : 42}\n", |
| 52 | + "print(dict['foo'])\n", |
| 53 | + "print(len(dict))" |
| 54 | + ] |
| 55 | + }, |
| 56 | + { |
| 57 | + "cell_type": "markdown", |
| 58 | + "metadata": {}, |
| 59 | + "source": [ |
| 60 | + "## Differences between list and Dictonary \n", |
| 61 | + " - To access values in list you have to give index, whereas in dictonaries you have to give keys.\n", |
| 62 | + " - List stores data sequentially, whereas Dictonary doesnot stores data sequentially thats why we access values with help of key.\n" |
| 63 | + ] |
| 64 | + }, |
| 65 | + { |
| 66 | + "cell_type": "code", |
| 67 | + "execution_count": 18, |
| 68 | + "metadata": {}, |
| 69 | + "outputs": [ |
| 70 | + { |
| 71 | + "ename": "KeyError", |
| 72 | + "evalue": "'foo'", |
| 73 | + "output_type": "error", |
| 74 | + "traceback": [ |
| 75 | + "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m", |
| 76 | + "\u001b[1;31mKeyError\u001b[0m Traceback (most recent call last)", |
| 77 | + "\u001b[1;32m<ipython-input-18-23eff5f25f73>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m 1\u001b[0m \u001b[0mspam\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m{\u001b[0m\u001b[1;34m'bar'\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;36m100\u001b[0m\u001b[1;33m}\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m 2\u001b[0m \u001b[1;31m## we will get key error as we haven't defined any key:value pair named foo\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 3\u001b[1;33m \u001b[0mspam\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'foo'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m", |
| 78 | + "\u001b[1;31mKeyError\u001b[0m: 'foo'" |
| 79 | + ] |
| 80 | + } |
| 81 | + ], |
| 82 | + "source": [ |
| 83 | + "spam = {'bar':100}\n", |
| 84 | + "## we will get key error as we haven't defined any key:value pair named foo\n", |
| 85 | + "spam['foo']" |
| 86 | + ] |
| 87 | + }, |
| 88 | + { |
| 89 | + "cell_type": "code", |
| 90 | + "execution_count": 23, |
| 91 | + "metadata": {}, |
| 92 | + "outputs": [ |
| 93 | + { |
| 94 | + "data": { |
| 95 | + "text/plain": [ |
| 96 | + "True" |
| 97 | + ] |
| 98 | + }, |
| 99 | + "execution_count": 23, |
| 100 | + "metadata": {}, |
| 101 | + "output_type": "execute_result" |
| 102 | + } |
| 103 | + ], |
| 104 | + "source": [ |
| 105 | + "spam = {'cat':'meow','dog':'bow'}\n", |
| 106 | + "'cat' in spam.keys()" |
| 107 | + ] |
| 108 | + }, |
| 109 | + { |
| 110 | + "cell_type": "code", |
| 111 | + "execution_count": 24, |
| 112 | + "metadata": {}, |
| 113 | + "outputs": [ |
| 114 | + { |
| 115 | + "data": { |
| 116 | + "text/plain": [ |
| 117 | + "True" |
| 118 | + ] |
| 119 | + }, |
| 120 | + "execution_count": 24, |
| 121 | + "metadata": {}, |
| 122 | + "output_type": "execute_result" |
| 123 | + } |
| 124 | + ], |
| 125 | + "source": [ |
| 126 | + "'cat' in spam" |
| 127 | + ] |
| 128 | + }, |
| 129 | + { |
| 130 | + "cell_type": "markdown", |
| 131 | + "metadata": {}, |
| 132 | + "source": [ |
| 133 | + "## There is no difference proved in above code as in operator checks whether a value exists as a key in the dictionary or not." |
| 134 | + ] |
| 135 | + }, |
| 136 | + { |
| 137 | + "cell_type": "code", |
| 138 | + "execution_count": 25, |
| 139 | + "metadata": {}, |
| 140 | + "outputs": [ |
| 141 | + { |
| 142 | + "data": { |
| 143 | + "text/plain": [ |
| 144 | + "True" |
| 145 | + ] |
| 146 | + }, |
| 147 | + "execution_count": 25, |
| 148 | + "metadata": {}, |
| 149 | + "output_type": "execute_result" |
| 150 | + } |
| 151 | + ], |
| 152 | + "source": [ |
| 153 | + "'cat' in spam" |
| 154 | + ] |
| 155 | + }, |
| 156 | + { |
| 157 | + "cell_type": "code", |
| 158 | + "execution_count": 26, |
| 159 | + "metadata": {}, |
| 160 | + "outputs": [ |
| 161 | + { |
| 162 | + "data": { |
| 163 | + "text/plain": [ |
| 164 | + "False" |
| 165 | + ] |
| 166 | + }, |
| 167 | + "execution_count": 26, |
| 168 | + "metadata": {}, |
| 169 | + "output_type": "execute_result" |
| 170 | + } |
| 171 | + ], |
| 172 | + "source": [ |
| 173 | + "'cat' in spam.values()" |
| 174 | + ] |
| 175 | + }, |
| 176 | + { |
| 177 | + "cell_type": "markdown", |
| 178 | + "metadata": {}, |
| 179 | + "source": [ |
| 180 | + "## In the above 2 blocks of code 'cat' in spam finds if there is a key named 'cat' whereas 'cat' in spam.values() finds 'cat' in values of dictonary" |
| 181 | + ] |
| 182 | + }, |
| 183 | + { |
| 184 | + "cell_type": "code", |
| 185 | + "execution_count": 36, |
| 186 | + "metadata": {}, |
| 187 | + "outputs": [ |
| 188 | + { |
| 189 | + "data": { |
| 190 | + "text/plain": [ |
| 191 | + "{'cat': 'meow', 'dog': 'bow', 'color': 'black'}" |
| 192 | + ] |
| 193 | + }, |
| 194 | + "execution_count": 36, |
| 195 | + "metadata": {}, |
| 196 | + "output_type": "execute_result" |
| 197 | + } |
| 198 | + ], |
| 199 | + "source": [ |
| 200 | + "## shortcut for the following code?\n", |
| 201 | + "## if 'color' not in spam:\n", |
| 202 | + "## spam['color'] = 'black'\n", |
| 203 | + "spam.setdefault('color', 'black')\n", |
| 204 | + "spam['color']\n", |
| 205 | + "spam" |
| 206 | + ] |
| 207 | + }, |
| 208 | + { |
| 209 | + "cell_type": "code", |
| 210 | + "execution_count": 70, |
| 211 | + "metadata": {}, |
| 212 | + "outputs": [ |
| 213 | + { |
| 214 | + "name": "stdout", |
| 215 | + "output_type": "stream", |
| 216 | + "text": [ |
| 217 | + "{ 'cat': 'meow',\n", |
| 218 | + " 'color': 'black',\n", |
| 219 | + " 'dog': 'bow'}\n" |
| 220 | + ] |
| 221 | + } |
| 222 | + ], |
| 223 | + "source": [ |
| 224 | + "import pprint\n", |
| 225 | + "pprint.pprint(spam,indent = 50,width=10, compact=False)" |
| 226 | + ] |
| 227 | + } |
| 228 | + ], |
| 229 | + "metadata": { |
| 230 | + "kernelspec": { |
| 231 | + "display_name": "Python 3", |
| 232 | + "language": "python", |
| 233 | + "name": "python3" |
| 234 | + }, |
| 235 | + "language_info": { |
| 236 | + "codemirror_mode": { |
| 237 | + "name": "ipython", |
| 238 | + "version": 3 |
| 239 | + }, |
| 240 | + "file_extension": ".py", |
| 241 | + "mimetype": "text/x-python", |
| 242 | + "name": "python", |
| 243 | + "nbconvert_exporter": "python", |
| 244 | + "pygments_lexer": "ipython3", |
| 245 | + "version": "3.8.5" |
| 246 | + } |
| 247 | + }, |
| 248 | + "nbformat": 4, |
| 249 | + "nbformat_minor": 4 |
| 250 | +} |
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