Does NLTK return different results on each run?
Both the tagger and the tokenizer are deterministic. While it's possible that iterating over a Python dictionary would return results in a different order in each execution of the program, this will not affect tokenization -- and hence the number of tokens (tagged or not) should not vary. Something else is wrong with your code.
Does Python's NLTK toolkit return different results for each iteration of:
1) tokenization
2) POS tagging?
I am using NLTK to tag a large text file. The tokenized list of tuples has a different size every time. Why is this?