Exploring the newsgroups data

After we download the 20 newsgroups dataset by whatever means we prefer, the data object of groups is cached in memory. The data object is in the form of a key-value dictionary. Its keys are as follows:

>>> groups.keys()
dict_keys(['data', 'filenames', 'target_names', 'target', 'DESCR'])

The target_names key gives the 20 newsgroups names:

>>> groups['target_names']
   ['alt.atheism', 'comp.graphics', 'comp.os.ms-windows.misc', 'comp.sys.ibm.pc.hardware', 'comp.sys.mac.hardware', 'comp.windows.x', 'misc.forsale', 'rec.autos', 'rec.motorcycles', 'rec.sport.baseball', 'rec.sport.hockey', 'sci.crypt', 'sci.electronics', 'sci.med', 'sci.space', 'soc.religion.christian', 'talk.politics.guns', 'talk...