Utility class for recursing over nested iterables
| 65 | |
| 66 | |
| 67 | class _Recurser: |
| 68 | """ |
| 69 | Utility class for recursing over nested iterables |
| 70 | """ |
| 71 | |
| 72 | # This was copied almost verbatim from numpy.core.shape_base._Recurser |
| 73 | # See numpy license at https://github.com/numpy/numpy/blob/master/LICENSE.txt |
| 74 | # or NUMPY_LICENSE.txt within this directory |
| 75 | |
| 76 | def __init__(self, recurse_if): |
| 77 | self.recurse_if = recurse_if |
| 78 | |
| 79 | def map_reduce( |
| 80 | self, |
| 81 | x, |
| 82 | f_map=lambda x, **kwargs: x, |
| 83 | f_reduce=lambda x, **kwargs: x, |
| 84 | f_kwargs=lambda **kwargs: kwargs, |
| 85 | **kwargs, |
| 86 | ): |
| 87 | """ |
| 88 | Iterate over the nested list, applying: |
| 89 | * ``f_map`` (T -> U) to items |
| 90 | * ``f_reduce`` (Iterable[U] -> U) to mapped items |
| 91 | |
| 92 | For instance, ``map_reduce([[1, 2], 3, 4])`` is:: |
| 93 | |
| 94 | f_reduce([ |
| 95 | f_reduce([ |
| 96 | f_map(1), |
| 97 | f_map(2) |
| 98 | ]), |
| 99 | f_map(3), |
| 100 | f_map(4) |
| 101 | ]]) |
| 102 | |
| 103 | |
| 104 | State can be passed down through the calls with `f_kwargs`, |
| 105 | to iterables of mapped items. When kwargs are passed, as in |
| 106 | ``map_reduce([[1, 2], 3, 4], **kw)``, this becomes:: |
| 107 | |
| 108 | kw1 = f_kwargs(**kw) |
| 109 | kw2 = f_kwargs(**kw1) |
| 110 | f_reduce([ |
| 111 | f_reduce([ |
| 112 | f_map(1), **kw2) |
| 113 | f_map(2, **kw2) |
| 114 | ], **kw1), |
| 115 | f_map(3, **kw1), |
| 116 | f_map(4, **kw1) |
| 117 | ]], **kw) |
| 118 | """ |
| 119 | |
| 120 | def f(x, **kwargs): |
| 121 | if not self.recurse_if(x): |
| 122 | return f_map(x, **kwargs) |
| 123 | else: |
| 124 | next_kwargs = f_kwargs(**kwargs) |