Hyperparameter Optimization using Genetic Algorithm for an Image Segmentation CNN model

Hi All,

I have a CNN model that does foreground segmentation from images. I understand that the MATLAB experiment manager allows me to optimize the hyperparameters of the CNN directly using the bayesian approach without going for any coding. Is there any means(any tool or code fragment) by which I can use genetic algorithm for this optimization in MATLAB. Any help would be highly appreciated.

Thanks in advance

Answer 1

[Sai Gokul]

Hi Parvathy

I understand you want to use genetic algorithm to optimize the hyperparameters

Here is an approach you can follow

1. Define the Objective Function: Start by defining an objective function that evaluates the performance of your CNN model given a set of hyperparameters. This function should take the hyperparameters as input, train the CNN model with those hyperparameters, and return a performance metric (e.g., accuracy, F1 score) that you want to maximize or minimize.
2. Define the Hyperparameter Bounds: Specify the bounds for each hyperparameter that you want to optimize. For example, you might have bounds for learning rate, batch size, number of layers, etc. These bounds will be used by the GA to generate initial populations and perform mutation and crossover operations.
3. Set Up the Optimization Problem: Use the 'gaoptimset' function to create an optimization options structure. This structure will define various settings for the GA, such as the objective function, hyperparameter bounds, population size, number of generations, etc.
4. Run the Genetic Algorithm: Use the 'ga' function to run the GA optimization. Pass the objective function and the optimization options structure as inputs to the ga function. This will start the optimization process, and the GA will iteratively search for the best set of hyperparameters that maximize or minimize the objective function.
5. Analyze the Results: Once the GA optimization is complete, you can analyze the results to identify the best set of hyperparameters and the corresponding performance metric achieved by your CNN model.

Here is an example code to demostrate the above approach

% Define the objective function
objectiveFcn = @(x) yourCNNModel(x); % Replace with your own objective function

% Define the hyperparameter bounds
lb = [lower_bound1, lower_bound2, ...]; % Lower bounds for each hyperparameter
ub = [upper_bound1, upper_bound2, ...]; % Upper bounds for each hyperparameter

% Set up the optimization problem
options = gaoptimset('Display', 'iter', 'PopulationSize', 50, 'Generations', 10);
options = gaoptimset(options, 'PlotFcn', {@gaplotbestf, @gaplotstopping});

% Run the genetic algorithm
[x, fval] = ga(objectiveFcn, numVars, [], [], [], [], lb, ub, [], options);

% Analyze the results
bestHyperparameters = x;
bestPerformance = fval;

You can refer to the below documentation to more about Genetic Algorithm Optimization

Genetic Algorithm - MATLAB & Simulink - MathWorks India

Hope this helps!