A District Nobody Saw

A house-price model target-encodes the district column. Some new houses are in districts the encoder never saw during training.

Task: write encode_districts(train_districts, train_prices, new_districts, smooth).

• Put the districts in one-column DataFrames with the column name "district". The prices are a list of numbers, one per training house.
• Fit a TargetEncoder(smooth=smooth, target_type="continuous") on the training districts and prices.
• Transform new_districts with it. A district the encoder never saw gets the overall average price of the training houses.
• Return the encoded values as a list, each rounded to 1 decimal place.