Negative R2_score Bad predictions for my Sales prediction problem using LightGBM
I assume you are new to the field, thus, I would suggest using tutorials to achieve your goal. Because what you did is completely wrong and your approach is incorrect. I guess you want to model the sales as time series without using any predictor instead you want to model future values by looking at the past values. To achieve that, you need to use algorithms like ARIMA, exponential smoothing, etc. Here what you have done is trying to correlate the year, month, and day with the sales, which does not possess any information about the sale as expected (also you decoded it wrongly). Thus, your performance metric shows you a negative result. As a reference, check these which are similar to your problem. Source1, Source2, Source3. These will solve your issue.