.set_param()

Set a hyperparameter value for one or all parameter groups.

This is the general-purpose setter for any hyperparameter stored in param_groups (e.g. "lr", "momentum", "beta_1"). When updating "lr" across all groups, self.lr is also kept in sync for scheduler compatibility.

Parameters:

• key (str) –

  Name of the hyperparameter to update (e.g. "lr").

• value –

  New value to assign.

• group (str | None, default: None ) –

  Label of the group to update. If None, all groups are updated.

Raises:

• KeyError –

  If key does not exist in the targeted group(s).