sibe
====
A simple Machine Learning library.

## Simple neural network
```haskell
    let a = (sigmoid, sigmoid') -- activation function
        -- random network, seed 0, values between -1 and 1,
        -- two inputs, two nodes in hidden layer and a single output
        rnetwork = randomNetwork 0 (-1, 1) 2 [(2, a)] (1, a)

        -- inputs and labels
        inputs = [vector [0, 1], vector [1, 0], vector [1, 1], vector [0, 0]]
        labels = [vector [1], vector [1], vector [0], vector [0]]

        -- define the session which includes parameters
        session = def { network = rnetwork
                      , learningRate = 0.5
                      , epochs = 1000
                      , training = zip inputs labels
                      , test = zip inputs labels
                      , drawChart = True
                      , chartName = "nn.png" -- draws chart of loss over time
                      } :: Session

        initialCost = crossEntropy session

    -- run gradient descent
    -- you can also use `sgd`, see the notmnist example
    newsession <- run gd session

    let results = map (`forward` newsession) inputs
        rounded = map (map round . toList) results

        cost = crossEntropy newsession
    
    putStrLn $ "- initial cost (cross-entropy): " ++ show initialCost
    putStrLn $ "- actual result: " ++ show results
    putStrLn $ "- rounded result: " ++ show rounded
    putStrLn $ "- cost (cross-entropy): " ++ show cost
```


## Examples
```bash
# neural network examples
stack exec example-xor
stack exec example-424
# notMNIST dataset, achieves ~87.5% accuracy after 9 epochs
stack exec example-notmnist

# Naive Bayes document classifier, using Reuters dataset
# using Porter stemming, stopword elimination and a few custom techniques.
# The dataset is imbalanced which causes the classifier to be biased towards some classes (earn, acq, ...)
# to workaround the imbalanced dataset problem, there is a --top-ten option which classifies only top 10 popular
# classes, with evenly split datasets (100 for each), this increases F Measure significantly, along with ~10% of improved accuracy
# N-Grams don't seem to help us much here (or maybe my implementation is wrong!), using bigrams increases
# accuracy, while decreasing F-Measure slightly.
stack exec example-naivebayes-doc-classifier -- --verbose
stack exec example-naivebayes-doc-classifier -- --verbose --top-ten
```

### notMNIST

notMNIST dataset, sigmoid hidden layer, cross-entropy loss, learning rate decay and sgd ([`notmnist.hs`](https://github.com/mdibaiee/sibe/blob/master/examples/notmnist.hs)):
![notMNIST](https://github.com/mdibaiee/sibe/blob/master/notmnist.png?raw=true)

notMNIST dataset, relu hidden layer, cross-entropy loss, learning rate decay and sgd ([`notmnist.hs`](https://github.com/mdibaiee/sibe/blob/master/examples/notmnist.hs)):
![notMNIST](https://github.com/mdibaiee/sibe/blob/master/notmnist-relu.png?raw=true)

### Word2Vec

word2vec on a very small sample text:

```
the king loves the queen
the queen loves the king,
the dwarf hates the king
the queen hates the dwarf
the dwarf poisons the king
the dwarf poisons the queen
the man loves the woman
the woman loves the man,
the thief hates the man
the woman hates the thief
the thief robs the man
the thief robs the woman
```

The computed vectors are transformed to two dimensions using PCA:

`king` and `queen` have a relation with `man` and `woman`, `love` and `hate` are close to each other,
and `dwarf` and `thief` have a relation with `poisons` and `robs`, also, `dwarf` is close to `queen` and `king` while
`thief` is closer to `man` and `woman`. `the` doesn't relate to anything.
![word2vec results](https://raw.githubusercontent.com/mdibaiee/sibe/master/w2v.png)

_You can reproduce this result using these parameters:_
```haskell
let session = def { learningRate = 0.1
                  , batchSize = 1
                  , epochs = 10000
                  , debug = True
                  } :: Session
    w2v = def { docs = ds
              , dimensions = 30
              , method = SkipGram
              , window = 2
              , w2vDrawChart = True
              , w2vChartName = "w2v.png"
              } :: Word2Vec
```

This is a very small development dataset and I have to test it on larger datasets.