I want to do this:

I have 2D-tensor, matrix with shape=(None, 4), so N examples with 4 element, 
[x, y, a, b].

```
X = tf.placeholder(tf.float32, shape=(None, 4))

```

In next step, I want to have matrix m x n with value b at coordinates (x, y)

Shape of Y is also given. e.g. shapeY = (5, 5)

Example:

Input:

```
X = np.array([[0, 0, 10, 10], 
              [1, 1, 20, 20], 
              [2, 2, 30, 30], 
              [3, 3, 40, 40], 
              [4, 4, 50, 50]])

```

Output:

```
Y = [[10, 0, 0, 0, 0],
     [0, 20, 0, 0, 0],
     [0, 0, 30, 0, 0],
     [0, 0, 0, 40, 0],
     [0, 0, 0, 0, 50]]

```

This example is with actual values, but I need this with placeholders as part of tensorflow graph, before I pass real values. Result must be like this.