在Python3中,字典
keys
返回“视图”,而不是可索引列表。
In [80]: d={'a':1, 'b':2}
In [81]: d.keys()
Out[81]: dict_keys(['a', 'b'])
In [82]: d.keys()[0]
....
TypeError: 'dict_keys' object does not support indexing
h5
组
In [86]: f = h5py.File('data.h5')
In [87]: f.keys()
Out[87]: KeysView(<HDF5 file "data.h5" (mode r+)>)
In [88]: f.keys()[0]
....
TypeError: 'KeysView' object does not support indexing
In [89]: list(f.keys())
Out[89]: ['dset', 'dset1', 'vset']
In [90]: list(f.keys())[1]
Out[90]: 'dset1'
list
这有点麻烦,但它使键上的迭代更有内存效率。
In [92]: for k in f.keys():print(f[k])
<HDF5 dataset "dset": shape (3, 5), type "<f8">
<HDF5 dataset "dset1": shape (2, 3, 10), type "<f8">
<HDF5 dataset "vset": shape (100,), type "|O">