learner.py

from fastai.conv_learner import ConvLearner, num_cpus, accuracy

def get_learner(arch, bs):
    """Create a FastAI learner using the given model"""
    data = get_data(bs, num_cpus())
    learn = ConvLearner.from_model_data(arch.cuda(), data)
    learn.crit = nn.CrossEntropyLoss()
    learn.metrics = [accuracy]
    return learn

def get_TTA_accuracy(learn):
    """Calculate accuracy with Test Time Agumentation(TTA)"""
    preds, targs = learn.TTA()
    preds = 0.6 * preds[0] + 0.4 * preds[1:].sum(0)
    return accuracy_np(preds, targs)