theano - print value of TensorVariable

Question

How can I print the numerical value of a theano TensorVariable? I'm new to theano, so please be patient :) I have a function where I get `y` as a parameter. Now I want to debug-print the shape of this `y` to the console. Using ``` print y.shape ``` results in the console output (i was expecting numbers, i.e. `(2,4,4)`): ``` Shape.0 ``` Or how can I print the numerical result of for example the following code (this counts how many values in `y` are bigger than half the maximum): ``` errorCount = T.sum(T.gt(T.abs_(y),T.max(y)/2.0)) ``` `errorCount` should be a single number because `T.sum` sums up all the values. But using ``` print errCount ``` gives me (expected something like `134`): ``` Sum.0 ```

Accepted Answer

If y is a theano variable, y.shape will be a theano variable. so it is normal that

```
print y.shape
```

return:

```
Shape.0
```

If you want to evaluate the expression y.shape, you can do:

```
y.shape.eval()
```

if `y.shape` do not input to compute itself(it depend only on shared variable and constant). Otherwise, if `y` depend on the `x` Theano variable you can pass the inputs value like this:

```
y.shape.eval(x=numpy.random.rand(...))
```

this is the same thing for the `sum`. Theano graph are symbolic variable that do not do computation until you compile it with `theano.function` or call `eval()` on them.

EDIT: Per the docs, the syntax in newer versions of theano is

```
y.shape.eval({x: numpy.random.rand(...)})
```

theano - print value of TensorVariable

Solution

Problem