How to change index dtype of pandas DataFrame to int32?

Question

A default dtype of DataFrame index is int64 and I would like to change it to int32.

I tried changing it with pd.DataFrame.set_index and Num

Answer 1

All of the code paths I could find, coerce the dtype:

Check in pandas.Index.__new__()

if issubclass(data.dtype.type, np.integer):
    from .numeric import Int64Index
    return Int64Index(data, copy=copy, dtype=dtype, name=name)

This allows passing a dtype, but in NumericIndex().__new__() we have:

if copy or not is_dtype_equal(data.dtype, cls._default_dtype):
    subarr = np.array(data, dtype=cls._default_dtype, copy=copy)

Which changes the dtype.