In [1]: 
from nltk.corpus.reader import TaggedCorpusReader
from nltk.tag import AffixTagger
import pickle
In [2]: 
#trainer
reader = TaggedCorpusReader('.', 'latin_training_set.pos')
train_sents = reader.tagged_sents()

2-char prefix tagger

In [3]: 
two_prefix_tagger = AffixTagger(train_sents, affix_length=2)
In [4]: 
two_prefix_tagger.evaluate(train_sents)
Out[4]:
0.11491635775172647

3-char prefix tagger

In [5]: 
three_prefix_tagger = AffixTagger(train_sents, affix_length=3)
In [6]: 
three_prefix_tagger.evaluate(train_sents)
Out[6]:
0.15512861524565794

4-char prefix tagger

In [7]: 
four_prefix_tagger = AffixTagger(train_sents, affix_length=4)
In [8]: 
four_prefix_tagger.evaluate(train_sents)
Out[8]:
0.16120655589635513

2-char suffix tagger

In [9]: 
suffix_tagger = AffixTagger(train_sents, affix_length=-2)
In [10]: 
suffix_tagger.evaluate(train_sents)
Out[10]:
0.22117682479348175

3-char suffix tagger

In [11]: 
three_suffix_tagger = AffixTagger(train_sents, affix_length=-3)
In [12]: 
three_suffix_tagger.evaluate(train_sents)
Out[12]:
0.2615772538245865

4-char suffix tagger

In [13]: 
four_suffix_tagger = AffixTagger(train_sents, affix_length=-4)
In [14]: 
four_suffix_tagger.evaluate(train_sents)
Out[14]:
0.2749374329638899

5-char suffix tagger

In [15]: 
five_suffix_tagger = AffixTagger(train_sents, affix_length=-5)
In [16]: 
five_suffix_tagger.evaluate(train_sents)
Out[16]:
0.2376041999887097

6-char suffix tagger

In [17]: 
six_suffix_tagger = AffixTagger(train_sents, affix_length=-6)
In [18]: 
six_suffix_tagger.evaluate(train_sents)
Out[18]:
0.1721957736672751