NLP Techniques on Hindi

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Assignment-1

Link to datasets: https://github.com/UniversalDependencies/UD_Hindi-HDTB/tree/master
The corpus files are available from https://indicnlp.ai4bharat.org/corpora/#downloads

• Performed unicode correction for Hindi

  • The default unicode of Hindi characters are not correct:
    For eg., The unicode bifercation of character in "कल्पना" comes out to be: ['क', 'ल', '्', 'प', 'न', 'ा'] which is wrong.
    Its correct unicode is: ['क्', 'अ', 'ल्', 'प्', 'अ', 'न्', 'आ']
    

• Cleaned the corpus, i.e., get rid of non-language characters

• Considering a word as a white-space separated sequence of characters. For each word, found the characters and the syllables. Stored a list of them and the words in descending order of their frequencies.
  

  • {'करने': [['क्', 'अ', 'र्', 'अ', 'न्', 'ए'], 6, ['क', 'र', 'ने'], 3]}

• Found the bi-gram frequencies of syllables and characters

  • ('आ', 'वे'): 3, ('वे', 'द'): 3

• Implemented BPE on the corpus with different vocabulary sizes.

  • For each token thus found, found the characters and the syllables, the unigram and bi-gram frequencies of tokens, syllables and characters

• For each vocabulary size of BPE, found the precision, recall and F-score of the BPE-output token set as found previously

• Extracted a list of lemmas and the corresponding surface forms found from the UD- tagged files

• Drawn the frequency v/s rank plot of whitespace-separated words, BPE tokens, syllables, characters, lemmas and verified if they follow Zipfian law

• Given a lemma and the corresponding surface form, derived the suffix. Performed an end stripping from the surface form till the lemma or a subset of the lemma is reached (chosen the longer one). Called the stripped part as the suffix. Listed the 50 most common suffixes ordered in this manner.

Assignment-2

The Python code notebook for BERT MODEL and the respective datasets can be found at:
https://drive.google.com/drive/folders/1VKwQtnSRqWERULev2JwXKj6Y4Ow61EPk?usp=sharing.
The BERT models are listed in https://huggingface.co/ai4bharat/indic-bert.

• In the parse file attached, Consider a particular sentence S consisting of n words w1 . . . wn.
  Corresponding to that are the POS tags t1 . . . tn.
  For each word wi, assume the gender, case and number to be gi, ci and bi respectively.
  There are also n dependency relations in the sentence (including the one with the root). Assume a dependency relation to be ⟨wi,R,wj⟩ which indicates that the word wi is connected to its head word wj by the relation R. Correspondingly, the POS tag relation is ⟨ti,R,tj⟩.
  For each of the questions below, output the list in descending order of frequencies:
  
  • Found the frequencies of POS tags of words.
    
  • Listed the 50 most frequent words corresponding to each POS tag.
    
  • Found the frequencies of gender, case and number of words separately.
    
  • Listed the 50 most frequent combinations of gender, case and number as a 3-tuple.
    
  • Found the frequencies of POS tags corresponding to only head words.
    
  • Found the directed POS tag tuples, i.e., ⟨ti , tj ⟩. For each such 2-tuple, list the frequencies separately for each relation R as well as total.
    
  • For each dependency relation R, listed the frequencies separately for each 2-tuple ⟨ti,tj⟩ as well as total.
    
• Fine-tuned the pre-trained BERT model for the UPOS prediction task. Recorded precision, recall and F-score