copyConnect <source-group> <copy-group> <field> [-reset <reset-on-example> | -initOutput <init-output>]
When a group is given the type IN_COPY, OUT_COPY, or TARGET_COPY, it will copy its inputs, outputs, or targets from the units of another, source, group. However, the values needn't be copied from the same field in the units of the source group. For example, inputs to the copy group needn't be copied from the source group's inputs. You could copy the inputs from the outputs or targets or externalInputs of the source group.
Once a group has been given an IN_COPY, OUT_COPY, or TARGET_COPY type,
copyConnect must be called to tell it which is its source
group and which field of the source group's units the values are to be
The source and copy groups must have the same number of units.
Valid source group fields are
Copying from outputs to outputs is similar to what would happen if you
used an ELMAN type rather than OUT_COPY and called elmanConnect, rather than
copyConnect. However, these differ in a few important
ways. Error is backpropagated across an Elman connection, but not
across a copy connection. The Elman connection adds the source values
to the outputs, but the copy connection sets the outputs to the source
values. Typically, the context group precedes the source group in the
group ordering in an Elman connection. But in a copy connection, the
copy group will typically follow the source group.
If the copy group has more than one IN_COPY, OUT_COPY, or TARGET_COPY
type specified, the
copyConnect command applies to the
first one that doesn't yet have a source group. Not that you'd ever
actually want more than one.
To make group "foo" copy its outputs from the inputs of group "bar" and copy its targets from the outputs of group "baz", do:
lens> addGroup foo 10 OUT_COPY TARGET_COPY lens> copyConnect bar foo inputs lens> copyConnect baz foo outputs