Add ConstantOperator2

nifty5/operators/operator.py

@@ -179,6 +179,35 @@ class _ConstantOperator(Operator):
 
     def __repr__(self):
         return 'ConstantOperator <- {}'.format(self.domain.keys())
+
+
+class _ConstantOperator2(Operator):
+    def __init__(self, target, constant_output):
+        from ..sugar import makeDomain
+        self._target = makeDomain(target)
+        dom_keys = set(target.keys())-set(constant_output.domain.keys())
+        self._domain = makeDomain({key: self._target[key] for key in dom_keys})
+        self._constant_output = constant_output
+
+    def apply(self, x):
+        from ..linearization import Linearization
+        self._check_input(x)
+        if not isinstance(x, Linearization):
+            return x.unite(self._constant_output)
+        from .simple_linear_operators import _PartialExtractor
+
+        op = _PartialExtractor(self.target, x.jac.target).adjoint
+        val = x.val.unite(self._constant_output)
+
+        assert val.domain is self.target
+        assert val.domain is op.target
+
+        return x.new(val, op(x.jac))
+
+    def __repr__(self):
+        return 'ConstantOperator2: {} <- {}'.format(self.target.keys(), self.domain.keys())
+
+
 class _FunctionApplier(Operator):
     def __init__(self, domain, funcname):
         from ..sugar import makeDomain