the train.csv data contains all the incidents so the target will become a vector of 1's. you are correct. one needs to create a df with of all possible combinations of dates and road_segments and then merge the train data on to this grid (see starter code). then you have a much much larger dataset of which only some of the observations (those that matched the original train) will have target = 1.

Ohhh. That makes sense. Thanks a lot!