title: Share weights between two dense layers in keras
body: <p>I have a code as follows. What I want to do is to share the same weights in two dense layers.</p>
  
  <p>The equation for op1 and op2 layer will be like that</p>
  
  <p><code>op1 = w1y1 + w2y2 + w3y3 + w4y4 + w5y5 + b1</code></p>
  
  <p><code>op2 = w1z1 + w2z2 + w3z3 + w4z4 + w5z5 + b1</code></p>
  
  <p>here w1 to w5 weights are shared between op1 and op2 layer inputs which are (y1 to y5) and (z1 to z5) respectively.</p>
  
  <pre><code>ip_shape1 = Input(shape=(5,))
  ip_shape2 = Input(shape=(5,))
  
  op1 = Dense(1, activation = "sigmoid", kernel_initializer = "ones")(ip_shape1)
  op2 = Dense(1, activation = "sigmoid", kernel_initializer = "ones")(ip_shape2)
  
  merge_layer = concatenate([op1, op2])
  predictions = Dense(1, activation='sigmoid')(merge_layer)
  
  model = Model(inputs=[ip_shape1, ip_shape2], outputs=predictions)
  </code></pre>
  
  <p>Thanks in advance.</p>