Micro-Grad/engine.py at master · Youssef-Bahaa/Micro-Grad · GitHub

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import numpy as np

class Value:
    def __init__(self,data,children =(),op='',label =''):
        self.data = data
        self.prev = set(children)
        self.op = op
        self.label = label
        self.grad = 0
        self.backward_ = lambda:None

    def __add__(self, other):
        if not isinstance(other,Value):
            other = Value(other)
        out = Value(self.data + other.data,(self,other),'+')

        def backward_():
            self.grad  +=  out.grad * 1
            other.grad +=  out.grad * 1

        out.backward_ = backward_
        return out

    def __sub__(self, other):
        if not isinstance(other,Value):
            other = Value(other)
        out = Value(self.data - other.data,(self,other),'-')

        def backward_():
            self.grad  +=  out.grad *  1
            other.grad +=  out.grad * -1

        out.backward_ = backward_
        return out


    def __mul__(self, other):
        if not isinstance(other,Value):
            other = Value(other)
        out = Value(self.data * other.data,(self,other),'*')

        def backward_():
            self.grad  +=  out.grad * other.data
            other.grad +=  out.grad * self.data

        out.backward_ = backward_
        return out

    def __truediv__(self, other):
        if not isinstance(other, Value):
            other = Value(other)
        out = Value(self.data / other.data, (self, other), '/')

        def backward_():
            self.grad += out.grad * (1 / other.data)
            other.grad += out.grad * (-self.data / (other.data ** 2))

        out.backward_ = backward_
        return out

    def relu(self):
        x = self.data
        re = self.data if self.data > 0 else 0
        out = Value(re,(self,),'relu')

        def backward_():
            relu_derv = 1 if x > 0 else 0
            self.grad += out.grad * relu_derv

        out.backward_ = backward_
        return out

    def backward(self):
        topo = []
        visited = set()

        def build(v):
            if v not in visited:
                visited.add(v)
                for child in v.prev:
                    build(child)
                topo.append(v)

        build(self)

        self.grad = 1
        for node in reversed(topo):
            node.backward_()


    def __radd__(self, other):
        return self + other

    def __rsub__(self, other):
        if not isinstance(other, Value):
            other = Value(other)
        return other - self

    def __rmul__(self, other):
        return self * other

    def __neg__(self):
        return self * -1

    def __repr__(self):
        return f'Value(data = {self.data}, grad = {self.grad})'

    def __rtruediv__(self, other):
        if not isinstance(other, Value):
            other = Value(other)
        return other / self

if __name__ =='__main__':
    a  = Value(5)
    c = -a
    c.grad = 1
    c.backward()
    print(a)

'''a = Value(3) ; a.label = 'a'
b = Value(4) ; a.label = 'a'
c = a * b; c.label = 'c'

x = c.relu(); x.label = 'relu'

x.backward()

print(a.grad)
print(b.grad)'''