面试题与答案

The curse of dimensionality refers to the challenges and increased computational complexity that arise when working with high-dimensional data.

Example:

In high-dimensional space, data points become sparser, making it harder to generalize patterns.

Precision is the ratio of true positive predictions to the total predicted positives, while recall is the ratio of true positives to the total actual positives.

Example:

Precision: 90% of predicted spam emails were actually spam. Recall: 80% of actual spam emails were correctly predicted.

Overfitting occurs when a model learns the training data too well, capturing noise and irrelevant patterns. As a result, it performs poorly on new, unseen data.

Example:

A decision tree with too many branches that perfectly fit the training data but fails to generalize to new data.

Dimensionality reduction techniques reduce the number of features in a dataset while preserving its essential information. This helps mitigate the curse of dimensionality and improve model performance.

Example:

Applying Principal Component Analysis (PCA) to transform high-dimensional data into a lower-dimensional space.

Batch processing involves analyzing data in large chunks at scheduled intervals, while real-time processing analyzes data as it becomes available, providing immediate insights.

Example:

Batch processing: Nightly analysis of sales data. Real-time processing: Monitoring website traffic and updating recommendations in real-time.

Information gain measures the reduction in uncertainty or entropy after splitting a dataset based on a particular feature. It helps decide the order of attribute selection in a decision tree.

Example:

Choosing the attribute that maximizes information gain to split a dataset and create more homogenous subsets.

A ROC curve visualizes the trade-off between true positive rate and false positive rate at various classification thresholds. It helps evaluate the model's performance across different decision boundaries.

Example:

Assessing a medical diagnostic model's ability to discriminate between healthy and diseased individuals.

Lift measures the ratio of the observed support of a rule to the expected support if the antecedent and consequent were independent. It helps assess the significance of a rule.

Example:

If the lift is 2, it indicates that the rule has twice the likelihood of occurring compared to random chance.

Imbalanced datasets have unequal distribution of classes, leading to biased models. It can result in poor performance on the minority class and overfitting on the majority class.

Example:

A fraud detection model trained on a dataset where only 1% of transactions are fraudulent.