In a Support Vector Machine (SVM), several parameters play a crucial role in the model's behavior and performance. Here are some of the important parameters in SVM:
C (Regularization Parameter):
- Parameter
C
controls the trade-off between maximizing the margin and minimizing the classification error. - Smaller values of
C
lead to a larger margin but may allow some misclassifications. Larger values make the margin narrower but aim to minimize misclassifications.
- Parameter
Kernel Function:
- The choice of kernel function determines how SVM handles non-linear data. Common kernels include Linear, Polynomial, Radial Basis Function (RBF), and Sigmoid.
- Depending on the kernel, there may be kernel-specific parameters to tune (e.g., degree for Polynomial, gamma for RBF).
Gamma (γ):
- Gamma is a parameter used in the RBF kernel. It defines the shape of the decision boundary. Smaller values make the decision boundary smoother, while larger values make it more complex.
Degree (d): Poly
- Degree is a parameter used in the Polynomial kernel. It defines the degree of the polynomial used in the kernel function.
Class Weights:
- In cases of class imbalance, you can assign different weights to classes using the
class_weight
hyperparameter to penalize misclassifications of the minority class more heavily.
- In cases of class imbalance, you can assign different weights to classes using the
Tolerance (tol):
- Tolerance controls the stopping criterion for the optimization process. Smaller values may lead to longer training times but potentially better solutions.
Kernel Cache Size (cache_size):
- The amount of memory to allocate for the kernel cache. It can affect training time, especially for large datasets.
Decision Function Shape (decision_function_shape):
- For multi-class classification, this parameter determines how to compute decision values. It can be 'ovo' (one-vs-one) or 'ovr' (one-vs-rest).
Shrinking (shrinking):
- Shrinking heuristics can be used to speed up the training process by removing support vectors that are unlikely to change the result.
Probability Estimates (probability):
- Set to True if you need probability estimates from the SVM. This can be useful for obtaining class probabilities instead of just class labels.
Kernel Parameters (Specific to Kernel Type):
- Depending on the chosen kernel (e.g., RBF, Polynomial), there may be additional parameters to tune, such as gamma for RBF and degree for Polynomial.
These parameters allow you to control the behavior and performance of the SVM model. The choice of hyperparameters depends on the specific problem and dataset, and tuning them correctly is essential to achieve the best results.
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