Q:

How to check if a key exists in a word2vec trained model or not

I have trained a word2vec model using a corpus of documents with Gensim. Once the model is training, I am writing the following piece of code to get the raw feature vector of a word say "view".
myModel["view"]

However, I get a KeyError for the word which is probably because this doesn't exist as a key in the list of keys indexed by word2vec. How can I check if a key exits in the index before trying to get the raw feature vector?

A:

Word2Vec also provides a 'vocab' member, which you can access directly.
Using a pythonistic approach:
if word in w2v_model.vocab:
    # Do something

EDIT Since gensim release 2.0, the API for Word2Vec changed. To access the vocabulary you should now use this:
if word in w2v_model.wv.vocab:
    # Do something

EDIT 2 The attribute 'wv' is being deprecated and will be completed removed in gensim 4.0.0. Now it's back to the original answer by OP:
if word in w2v_model.vocab:
    # Do something

A:

convert the model into vectors with 
word_vectors = model.wv

then we can use 
if 'word' in word_vectors.vocab

