Wednesday, August 22, 2018

AI - Algorithm

  • Classification
    • The recommended approach
      • Use AUC to select the model when you do not know which threshold will be used
      • Then use FN and FP to decide the threshold
    • SVM
      • Pros
        • Accurate in high-dimensional spaces
        • Memory efficient
      • Cons
        • Prone to overfitting
        • No probability estimation
        • For small datasets
      • Applications
        • Image recognition
        • Text category assignment
        • Detecting spam
        • Sentiment  analysis
        • Gene expression classification
        • Regression, outlier detection and clustering
  • CNN
    • Kernel size?

      • Recent research has shown that it's better to use smaller kernel sizes and add more convolutional layers. In other words, instead of using a nine by nine filter, try sequencing two layers of three by three filters

  • RNN

    • Cell_size = N_inputs // (size of the internal state in each of the cell)

      • Lstm = 4 internal states

      • Gru = 3

    • Use custom loss function

      • E.g. use several outputs to calculate the loss

    • Dropout is available
  • Recommendation
    • Collaborative Filtering
      • User-based
      • Item-based
      • Challenges
        • Data sparsity
        • Cold start
        • Scalability
      • WALS: Weighted Alternating Least Squares
    • Context-aware

      • Contextual pre-filtering, contextual post-filtering, and contextual modeling

    • Hybrid

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