I need to perform sentiment analysis on topic modelling. I have used LDA with grid search search to identify the topic. The next step would be to perform sentiment analysis on it. How should I go about? What should be the training data and what should be the labels?
You should have a labeled training data from the outset for sentiment analysis.
For instance, each review should be labeled as 0 (negative) or 1 (positive).
If you do not have a labeled dataset, you cannot properly "train" the sentiment based on your topics.
Hence, with LDA, you can get features (i.e., topics) but you need targets (i.e., sentiments) already labeled as well.
If you do not have a labled dataset, you should artificially create it or use already-labeled toy datasets.
Below are examples of toy datasets