C2_W3 assigment calculate perplexity problem

Course Q&A Natural Language Processing NLP with Probabilistic Models
1

Hello I have a problem with calculate_perplexity function.
No matter how I try I cannot make it calculate perplexity correctly.

Here is my output from test sentence.

output_cropped
output_cropped495×831 30.8 KB

Here are what I have done already.

  1. In the first for loop I already ran i starting from n to N-1 (already check to include N-1)
  2. In defining n_gram, i already make sure it is splicing from string → I used sentence[:t]
  3. In probability I use estimate_probability function from previous code and use parameter from calculate_perplexity function.

I’m not sure why it still calculating wrong value.
Thanks

2

The problem should be at point 2, the slicing should start from the end of the previous word (with length n)!

3

Wow, finally got it. Thanks a lot.
So my slicing method is wrong. It shouldn’t start from zero.

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