Recently, I did a session at local user group in Ljubljana, Slovenija, where I introduced the new algorithms that are available with MicrosoftML package for Microsoft R Server 9.0.3.

For dataset, I have used two from (still currently) running sessions from Kaggle. In the last part, I did image detection and prediction of MNIST dataset and compared the performance and accuracy between.

MNIST Handwritten digit database is available here.

Starting off with rxNeuralNet, we have to build a NET# model or Neural network to work it’s way.

Model for Neural network:

const { T = true; F = false; }

input Picture [28, 28];

hidden C1 [5 * 13^2]
from Picture convolve {
InputShape  = [28, 28];
UpperPad    = [ 1,  1];
KernelShape = [ 5,  5];
Stride      = [ 2,  2];
MapCount = 5;
}

hidden C2 [50, 5, 5]
from C1 convolve {
InputShape  = [ 5, 13, 13];
KernelShape = [ 1,  5,  5];
Stride      = [ 1,  2,  2];
Sharing     = [ F,  T,  T];
MapCount = 10;
}

hidden H3 [100]
from C2 all;

// Output layer definition.
output Result [10]
from H3 all;

Once we have this, we can work out with rxNeuralNet algorithm:

model_DNN_GPU <- rxNeuralNet(label ~.
      ,data = dataTrain
      ,type = "multi"
      ,numIterations = 10
      ,normalize = "no"
      #,acceleration = "gpu" #enable this if you have CUDA driver
      ,miniBatchSize = 64 #set to 1 else set to 64 if you have CUDA driver problem 
      ,netDefinition = netDefinition
      ,optimizer = sgd(learningRate = 0.1, lRateRedRatio = 0.9, lRateRedFreq = 10)
)

Then do the prediction and calculate accuracy matrix:

DNN_GPU_score <- rxPredict(model_DNN_GPU, dataTest, extraVarsToWrite = "label")
sum(Score_DNN$Label == DNN_GPU_score$PredictedLabel)/dim(DNN_GPU_score)[1]

Accuracy for this model is:

[1] 0.9789

When working with H2O package, the following code was executed to get same paramethers for Neural network:

model_h20 <- h2o.deeplearning(x = 2:785
                     ,y = 1   # label for label
                     ,training_frame = train_h2o
                     ,activation = "RectifierWithDropout"
                     ,input_dropout_ratio = 0.2 # % of inputs dropout
                     ,hidden_dropout_ratios = c(0.5,0.5) # % for nodes dropout
                     ,balance_classes = TRUE 
                     ,hidden = c(50,100,100) 
                     ,momentum_stable = 0.99
                     ,nesterov_accelerated_gradient = T # use it for speed
                     ,epochs = 15)

When results of test dataset against the learned model is executed:

h2o.confusionMatrix(model_h20)
100-(416/9978)*100

the  result is confusion matrix for accuracy of predicted values with value of:

# [1] 95.83083

For comparison, I have added xgBoost (eXtrem Gradient Boosting), but this time, I will not focus on this one.

Time comparison against the packages (in seconds), from left to right are: H20, MicrosoftML with GPU acceleration, MicrosoftML without GPU acceleration and xgBoost.

As for the accuracy of the trained model, here are results (based on my tests):

MicrosoftML – Neural Network – 97,8%

H20 – Deep Learning – 95,3 %

xgBoost – 94,9 %

As always, code and dataset are available at GitHub.

Happy R-ing