add calculation for single feature data type

Author: FarrelAD

src/cli/main.js

@@ -23,7 +23,7 @@ import multiFeatureProcess from './multi-feature.js'
 const print = console.log;
 
 
-const DATA_DIR = path.join(path.dirname(fileURLToPath(import.meta.url)), '..', 'data');
+const DATA_DIR = path.join(path.dirname(fileURLToPath(import.meta.url)), '..', '..', 'data');
 
 
 /////////////////////////////////////////////////////////////////////
@@ -138,18 +138,7 @@ function readFileAsync(filePath) {
         fs.createReadStream(filePath)
             .pipe(csv())
             .on('data', (row) => data.push(row))
-            .on('end', () => {
-                const table = new Table({
-                    head: Object.keys(data[0])
-                })
-
-                data.forEach(row => {
-                    table.push(Object.values(row))
-                })
-
-                console.log(table.toString())
-                resolve()
-            })
+            .on('end', () => resolve(data))
             .on('error', (error) => reject(error))
     })
 }
@@ -162,17 +151,27 @@ async function previewData(filePath) {
     print('\n-----------------------------------------------------\n')
     print('Preview data: ', filePath)
 
-    await readFileAsync(path.join(DATA_DIR, filePath))
+    const data = await readFileAsync(path.join(DATA_DIR, filePath))
+
+    const table = new Table({
+        head: Object.keys(data[0])
+    })
+
+    data.forEach(row => {
+        table.push(Object.values(row))
+    })
+
+    print(table.toString())
 
     if (readlineSync.keyInYNStrict(chalk.green('\nContinue next process'))) {
-        await dataIdentification()
+        await dataIdentification(data)
     }
 }
 
 
 
 
-async function dataIdentification() {
+async function dataIdentification(data) {
     print('\n-----------------------------------------------------\n')
     print('Data identification')
 
@@ -191,10 +190,10 @@ async function dataIdentification() {
 
     switch (answers.type) {
         case '1. Single feature':
-            singleFeatureProcess()
+            await singleFeatureProcess(data)
             break;
         case '2. Multi feature':
-            multiFeatureProcess()
+            await multiFeatureProcess(data)
             break;
         default:
             print('Invalid input!')

src/cli/single-feature.js

@@ -1,20 +1,95 @@
 import chalk from 'chalk'
 import readlineSync from 'readline-sync'
+import inquirer from 'inquirer'
+import { input, confirm } from '@inquirer/prompts'
 
 
 
 const print = console.log;
 
 
-export default function singleFeatureProcess() {
-    print('Single feature process')
+
+/**
+ * Process linear regression with single feature
+ * 
+ * Formula
+ * y = a + bx
+ * 
+ * @param {Array} data - the raw data
+ */
+export default async function singleFeatureProcess(data) {
+    console.clear()
+    print('\n=====================================================\n')
+    print(chalk.blue('SINGLE FEATURE PROCESS\n'))
+
+    const answers = await inquirer.prompt([
+        {
+            type: 'list',
+            name: 'feature',
+            message: 'Choose feature',
+            choices: Object.keys(data[0])
+        },
+        {
+            type: 'list',
+            name: 'label',
+            message: 'Choose label',
+            choices: Object.keys(data[0])
+        }
+    ])
+
+
+    /**
+     * Calculate the value a and b to get equation y = a + bx
+     * Let's assume `feature` is `x` and `label` is `y`
+    */
+    const sumX = data.reduce((sum, val) => sum + parseInt(val[answers.feature]), 0)
+    const sumY = data.reduce((sum, val) => sum + parseInt(val[answers.label]), 0)
+    const sumXY = data.reduce((sum, val) => sum + (parseInt(val[answers.feature]) * parseInt(val[answers.label])), 0)
+    const sumXSquared = data.reduce((sum, val) => sum + parseInt(val[answers.feature]) ** 2, 0)
+    const sumXTimesSumY = sumX * sumY
+
+    const b = (
+        ((data.length * sumXY) - sumXTimesSumY) /
+        ((data.length * sumXSquared) - (sumX ** 2))
+    )
+
+    const a = (sumY / data.length) - (b * (sumX / data.length))
+
+    // Equation result
+    const y = (x) => a + (b * x)
+
+    // Print the equation
+    print(chalk.blueBright(`\nEquation result: ${a} + ${b}x`))
+
+
+
+    if (await confirm({ message: 'Do you want to test?'})) {
+        do {
+            await testing(y, answers.feature, answers.label)
+        } while (await confirm({ message: 'Do you want to test again?'}));
+    }
+    
+
+    evaluation()
 
     if (readlineSync.keyInYNStrict(chalk.green('\nShow visualization'))) {
         visualization()
     }
 }
 
 
+async function testing(y, feature, label) {
+    const inputFeature = await input({message: `Input ${feature}`})
+    print(`Prediction ${label}: ${y(inputFeature)}`)
+}
+
+
+function evaluation() {
+    print('Evaluation!')
+    print('MSE, MAE, RMSE')
+}
+
+
 
 function visualization() {
     print('\n-----------------------------------------------------\n')