在NLTK中有一个nltk.download()函数来下载NLP套件附带的数据集。在

我应该在哪里保存从源下载的数据？在我将数据保存到正确的目录之后，在我可以从python代码调用之前，是否还有其他步骤？在

是否有下载20newsgroups数据集的示例？

我已经安装了sklearn并尝试了这个，但是我得到了一个IOError。很可能是因为我还没有从源代码下载数据集。在>>> from sklearn.datasets import fetch_20newsgroups

>>> fetch_20newsgroups(subset='train')

Traceback (most recent call last):

File "", line 1, in

File "/usr/local/lib/python2.7/dist-packages/sklearn/datasets/twenty_newsgroups.py", line 207, in fetch_20newsgroups

cache_path=cache_path)

File "/usr/local/lib/python2.7/dist-packages/sklearn/datasets/twenty_newsgroups.py", line 89, in download_20newsgroups

tarfile.open(archive_path, "r:gz").extractall(path=target_dir)

File "/usr/lib/python2.7/tarfile.py", line 1678, in open

return func(name, filemode, fileobj, **kwargs)

File "/usr/lib/python2.7/tarfile.py", line 1727, in gzopen

**kwargs)

File "/usr/lib/python2.7/tarfile.py", line 1705, in taropen

return cls(name, mode, fileobj, **kwargs)

File "/usr/lib/python2.7/tarfile.py", line 1574, in __init__

self.firstmember = self.next()

File "/usr/lib/python2.7/tarfile.py", line 2334, in next

raise ReadError("empty file")

tarfile.ReadError: empty file