hash maps

Author: JeffreyAsuncion

data_structures/4_HashTable/Lab_2020_12_17.ipynb

@@ -0,0 +1,183 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# List or Array data structure - O(n)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "stock_prices = []\n",
+    "with open(\"stock_prices.csv\", \"r\") as f:\n",
+    "    for line in f:\n",
+    "        tokens = line.split(',')\n",
+    "        day = tokens[0]\n",
+    "        price = float(tokens[1])\n",
+    "        stock_prices.append([day, price])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[['march 6', 310.0],\n",
+       " ['march 7', 340.0],\n",
+       " ['march 8', 380.0],\n",
+       " ['march 9', 302.0],\n",
+       " ['march 10', 297.0],\n",
+       " ['march 11', 323.0]]"
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "stock_prices"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "302.0\n"
+     ]
+    }
+   ],
+   "source": [
+    "# this is O(n)\n",
+    "\n",
+    "for element in stock_prices:\n",
+    "    if element[0] == \"march 9\":\n",
+    "        print(element[1])"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Dictionary- Python's use of hash map/tables - O(1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "stock_prices = {}\n",
+    "with open(\"stock_prices.csv\", \"r\") as f:\n",
+    "    for line in f:\n",
+    "        tokens = line.split(',')\n",
+    "        day = tokens[0]\n",
+    "        price = float(tokens[1])\n",
+    "        stock_prices[day] = price"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{'march 6': 310.0,\n",
+       " 'march 7': 340.0,\n",
+       " 'march 8': 380.0,\n",
+       " 'march 9': 302.0,\n",
+       " 'march 10': 297.0,\n",
+       " 'march 11': 323.0}"
+      ]
+     },
+     "execution_count": 8,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "stock_prices"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "302.0"
+      ]
+     },
+     "execution_count": 11,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# this is O(1)\n",
+    "    \n",
+    "stock_prices['march 9']"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.8.5"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}