Test if an array is broadcastable to a shape?

Question

What is the best way to test whether an array can be broadcast to a given shape?

The \"pythonic\" approach of trying doesn\'t work for my case, because the

Answer 1

You could use np.broadcast. For example:

In [47]: x = np.ones([2,2,2])

In [48]: y = np.ones([2,3])

In [49]: try:
   ....:     b = np.broadcast(x, y)
   ....:     print "Result has shape", b.shape
   ....: except ValueError:
   ....:     print "Not compatible for broadcasting"
   ....:     
Not compatible for broadcasting

In [50]: y = np.ones([2,2])

In [51]: try:
   ....:     b = np.broadcast(x, y)
   ....:     print "Result has shape", b.shape
   ....: except ValueError:
   ....:     print "Not compatible for broadcasting"
   ....:
Result has shape (2, 2, 2)

For your implementation of lazy evaluation, you might also find np.broadcast_arrays useful.