Implement threshold-based rebalancing

To implement threshold-based rebalancing, we simply set a threshold for portfolio drift. To identify this, we can continue from our preceding example. First, we need a way to mark which portfolios require rebalancing. Let’s add a Boolean flag to our Portfolio class from before:

class Portfolio:
  def __init__(self, tickerString: str, expectedReturn: float, 
    portfolioName: str, riskBucket: int):
    self.name = portfolioName
    self.riskBucket = riskBucket
    self.expectedReturn = expectedReturn
    self.allocations = []
    self.needRebalancing = False

For the sake of brevity, I haven’t added the full Portfolio class, so just add this line to the __init__() method.

Let’s add a helper method to check whether our portfolio’s drift is higher than the threshold:

def checkNeedRebalancing...