Changes all measurements to a dephase operation.

This transformer is useful when using a density matrix simulator, when wishing to calculate the final density matrix of a circuit and not simulate the measurements themselves.

circuit The circuit to transform. It will not be modified.
context cirq.TransformerContext storing common configurable options for transformers. The default has deep=True to ensure measurements at all levels are dephased.

A copy of the circuit, with dephase operations in place of all measurements.

ValueError If the circuit contains classical controls. In this case, it is required to change these to quantum controls via cirq.defer_measurements first. Since deferral adds ancilla qubits to the circuit, this is not done automatically, to prevent surprises.