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Applies func to each entry in structure and returns a new structure.


Applies func(tuple_path, x[0], x[1], ..., **kwargs) where x[i] is an entry in structure[i] and tuple_path is a tuple of indices and/or dictionary keys (as returned by nest.yield_flat_paths), which uniquely specifies the common path to x[i] in the structures. All structures in structure must have the same arity, and the return value will contain the results in the same structure. Special kwarg check_types determines whether the types of iterables within the structure must be the same-- see **kwargs definition below.


  • func: A callable with the signature func(tuple_path, *values, **kwargs) that is evaluated on the leaves of the structure.
  • *structure: A variable number of compatible structures to process.
  • **kwargs: Optional kwargs to be passed through to func. Special kwarg check_types is not passed to func, but instead determines whether the types of iterables within the structures have to be same (e.g. map_structure(func, [1], (1,)) raises a TypeError exception). To allow this set this argument to False.


A structure of the same form as the input structures whose leaves are the result of evaluating func on corresponding leaves of the input structures.


  • TypeError: If func is not callable or if the structures do not match each other by depth tree.
  • TypeError: If check_types is not False and the two structures differ in the type of sequence in any of their substructures.
  • ValueError: If no structures are provided.