title: Save gensim Word2vec model in binary format .bin with save_word2vec_format
body: <p>I'm training my own word2vec model using different data. To implement the resulting model into my classifier and compare the results with the original pre-trained Word2vec model I need to save the model in binary extension .bin. Here is my code, <em>sentences</em> is a list of short messages.</p>
  
  <pre><code>import gensim, logging
  logging.basicConfig(format='%(asctime)s : %(levelname)s : %(message)s', level=logging.INFO)
  sentences = gensim.models.word2vec.LineSentence('dati.txt')
  model = gensim.models.Word2Vec(
  sentences, size=300, window=5, min_count=5, workers=5,
  sg=1, hs=1, negative=0
  )
  model.save_word2vec_format('model.bin', binary=True)
  </code></pre>
  
  <p>The last method, save_word2vec_format, gives me this error:</p>
  
  <p><code>
  AttributeError: 'Word2Vec' object has no attribute 'save_word2vec_format'
  </code></p>
  
  <p>What am I missing here? I've read the documentation of gensim and other forums. This <a href="https://github.com/devmount/GermanWordEmbeddings/blob/c2b603a07d968146995ee9dde54a25fd0aa8586a/training.py#L56" rel="noreferrer">repo on github</a> uses almost the same configuration so I cannot understand what's wrong. I've tried to switch from skipgram to cbow and from hierarchical softmax to negative sampling with no results.</p>
  
  <p>Thank you in advance!</p>