avatarNaina Chaturvedi

Summary

The website content provides a comprehensive guide to implementing logistic regression in a data science and machine learning context, including code examples, model training, and performance evaluation, alongside announcements for various related educational series and resources.

Abstract

The provided web content is centered around a detailed tutorial on logistic regression, which is part of a larger series on data science and machine learning. It begins by welcoming readers back to the series and introduces the project-based approach to learning logistic regression. The article then lists a variety of other educational series available on topics such as Natural Language Processing (NLP), Data Engineering, and System Design. It also promotes a newly launched YouTube channel, Ignito, which will publish videos on implemented projects and coding exercises. The author invites readers to subscribe to their tech newsletter for additional content, including tech interview tips and project tutorials.

The core of the content delves into the implementation of logistic regression, starting with the importation of necessary libraries and setting hyperparameters. It proceeds to load the dataset, create a logistic model, and define the forward pass, backward pass, and parameter update functions. The article also includes a section on checking the model's performance through prediction and evaluation functions. A training loop is provided to illustrate how the model learns from the data over multiple iterations, and the results of the model training are presented, showing improvements in accuracy and reductions in loss over time. Finally, the article concludes with a teaser for the next day's content, encouragement to follow along, and a quote from Steve Jobs to inspire continued learning and passion in the field.

Opinions

  • The author emphasizes the importance of a hands-on approach to learning data science and machine learning through projects.
  • There is a strong endorsement for the educational value of the provided series and resources, suggesting they are beneficial for learning and professional development in tech.
  • The author expresses enthusiasm for the field and encourages readers to engage with the content, subscribe to the newsletter, and follow the YouTube channel for more learning opportunities.
  • The inclusion of a quote by Steve Jobs at the end of the post reflects the author's belief in the importance of passion and perseverance in achieving success in tech and innovation.

Day 34: 60 days of Data Science and Machine Learning Series

Regression Project 4..

Pic credits : datatip

Welcome back peeps. In this post we will cover logistic regression with a project.

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30 Days of Natural Language Processing ( NLP) Series

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In logistic regression, we establish the relationship between the dependent variable and one or more independent variables by estimating probabilities using an equation ( logistic regression).

Let’s dive in!

Import necessary libraries

import random
import numpy as np
import warnings
import helpers.plt, helpers.dataset
from matplotlib import pyplot as plt
%matplotlib inline
warnings.filterwarnings('ignore')

Set Hyperparameters

These are the parameters ( examples as listed below) that is set before the learning process begins, are tunable and can directly affect how well a model trains.

  • Learning Rate
  • Regularization constant
  • Number of branches, Number of epochs
  • Number of clusters etc
lr = 0.3
batch_size = 300
iterations = 40

Load the Dataset

(X_train,Y_train), (X_test,Y_test) = helpers.dataset.get_data()
print('Shape of X_train:', X_train.shape)
print('Shape of Y_train:', Y_train.shape)
print('Shape of X_test:', X_test.shape)
print('Shape of Y_test:', Y_test.shape)

Output —

Shape of X_train: (12665, 28, 28)
Shape of Y_train: (12665,)
Shape of X_test: (2115, 28, 28)
Shape of Y_test: (2115,)

Create Model

A logistic model is simply a multi variable linear equation which gives a binary output.

class LogisticModel:
    def __init__(self, num_features):
       
        self.W = np.reshape(np.random.randn((num_features)),   
                 (num_features,1))
        self.b = np.zeros((1,1))
        self.num_features = num_features
        self.losses = []
        self.accuracies =[]
    def summary(self):

        print('Number of features:', self.num_features)
        print('Shape of weights:', self.W.shape)
        print('Shape of biases:', self.b.shape)
        
        

model = LogisticModel(num_features=784)
model.summary()

Output —

Number of features: 784
Shape of weights: (784, 1)
Shape of biases: (1, 1)

Forward Pass

class LogisticModel(LogisticModel):
    def _forward_pass(self, X, Y=None):
        
        batch_size = X.shape[0]
        Z = np.dot(X,self.W) +self.b
        A = 1./(1. +np.exp(-Z))
        loss = float(1e6)
        if Y is not None:
            loss = -1 * np.sum(np.dot(np.transpose(Y),\
            np.log(A))+  np.matmul(np.transpose(1-Y),np.log(1-A)))
            loss /= batch_size
        return A,loss

Backward Pass

class LogisticModel(LogisticModel):
    def _backward_pass(self, A, X, Y):
       
        batch_size = X.shape[0]
        dZ=A-Y
        dW = np.dot(np.transpose(X),dZ) / batch_size
        db = np.sum(dZ) /batch_size
        return dW,db

Update Parameters

class LogisticModel(LogisticModel):
    def _update_params(self, dW, db, lr):
      
        self.W -= lr * dW
        self.b -= lr * db

Check Model Performance

class LogisticModel(LogisticModel):
    def predict(self, X, Y=None):
        
        A,loss = self._forward_pass(X,Y)
        Y_hat = A > 0.5
        return np.squeeze(Y_hat),loss
    
    def evaluate(self, X, Y):
       
        Y_hat,loss = self.predict(X,Y)
        accuracy = np.sum(Y_hat == np.squeeze(Y))/ X.shape[0]
        return accuracy, loss
model =LogisticModel(784)
model.summary()
X,Y = helpers.dataset.get_random_batch(X_test,Y_test,batch_size)
acc,loss = model.evaluate(X,Y)
print("Accuracy:", acc)
print("Loss:", loss)

Output —

Number of features: 784
Shape of weights: (784, 1)
Shape of biases: (1, 1)

Accuracy: 0.25
Loss : 5.139016761351013

Training Loop

class LogisticModel(LogisticModel):
    def train(self, batch_size, get_batch, lr, iterations, X_train,  
              Y_train, X_test, Y_test):
       
        self.accuracies = []
        self.losses = []
        
        for i in range(iterations):
            X,Y = get_batch(X_train,Y_train,batch_size)
            A,_ = self._forward_pass(X,Y)
            dW,db = self._backward_pass(A,X,Y)
            self._update_params(dW,db,lr)
            
            X,Y = get_batch(X_test,Y_test,batch_size)
            val_acc,val_loss = self.evaluate(X,Y)
            self.accuracies.append(val_acc)
            self.losses.append(val_loss)
            print(i,val_acc,val_loss)

Model Training and Results

model = LogisticModel(784)
X,Y = helpers.dataset.get_random_batch(X_test,Y_test,batch_size)
model.train(
       batch_size,
       helpers.dataset.get_random_batch,
       lr, iterations, X_train, Y_train,
       X_test,Y_test
)
print(model.evaluate(X,Y))

Output —

0 0.38333333333333336 2.9112418287841
1 0.58 1.0920400376536754
2 0.8033333333333333 0.4733993185165991
3 0.8566666666666667 0.3860987796373691
4 0.92 0.22385032248466283
5 0.9433333333333334 0.16269221395977546
6 0.9533333333333334 0.13423627297149432
7 0.9333333333333333 0.1867625304499955
8 0.9766666666666667 0.08768901259572759
9 0.9733333333333334 0.09854519582688483
10 0.9766666666666667 0.07597673045261207
11 0.9766666666666667 0.0906360847939501
12 0.97 0.09736912192570973
13 0.99 0.05219127708236699
14 0.9833333333333333 0.06803636200857319
15 0.9766666666666667 0.05909810278419808
16 0.9733333333333334 0.04908840771386662
17 0.9666666666666667 0.11160536628554771
18 0.99 0.04569546767029207
19 0.9833333333333333 0.0630524474725281
20 0.9866666666666667 0.027689980368903376
21 0.9866666666666667 0.04844713667127785
22 0.99 0.03169328394070209
23 0.99 0.04417471252597749
24 0.99 0.03170499943380271
25 0.9933333333333333 0.012347557895914048
26 0.9833333333333333 0.05861541302888874
27 0.99 0.02411309909197451
28 0.9766666666666667 0.03870235621447865
29 0.9933333333333333 0.01807624105597577
30 0.9933333333333333 0.014707446692389648
31 0.9733333333333334 0.1001476449251274
32 0.9833333333333333 0.06153675229309561
33 0.9866666666666667 0.025670351820764055
34 0.9933333333333333 0.015290944469583451
35 0.99 0.023528542612788743
36 0.9933333333333333 0.01986740723553504
37 0.99 0.018890984240146534
38 0.98 0.050996656197463665
39 0.9966666666666667 0.01599068224616575
(0.9933333333333333, 0.026105419192584314)

Plot the results

helpers.plt.plot_metrics(model)

Day 35 : Coming soon

Follow and Stay tuned. Keep coding :)

For other projects, tune to —

Build Machine Learning Pipelines( With Code)

Recurrent Neural Network with Keras

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Custom Layers in Keras

That’s it fellas. Peace out and keep coding :)

Stay Tuned and of-course let me end this post with a quote by Steve Jobs ;)

“You have to be burning with an idea, or a problem, or a wrong that you want to right. If you’re not passionate enough from the start, you’ll never stick it out.”

Machine Learning
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Artificial Intelligence
Data Science
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