from fastai.gen_doc.nbdoc import *
from fastai import *

show_doc(accuracy)

show_doc(accuracy_thresh, doc_string=False)

show_doc(dice)

show_doc(fbeta)

show_doc(exp_rmspe)

class AverageMetric(Callback):
    def __init__(self, func):
        self.func, self.name = func, func.__name__

    def on_epoch_begin(self, **kwargs):
        self.val, self.count = 0.,0

    def on_batch_end(self, last_output, last_target, train, **kwargs):
        self.count += last_target.size(0)
        self.val += last_target.size(0) * self.func(last_output, last_target).detach().item()

    def on_epoch_end(self, **kwargs):
        self.metric = self.val/self.count

class Precision(Callback):
    
    def on_epoch_begin(self, **kwargs):
        self.correct, self.total = 0, 0
    
    def on_batch_end(self, last_output, last_target, **kwargs):
        preds = last_output.argmax(1)
        self.correct += ((preds==0) * (last_target==0)).float().sum()
        self.total += (preds==0).float().sum()
    
    def on_epoch_end(self, **kwargs):
        self.metric = self.correct/self.total