Uses Gamma/Gompertz/NBD model parameters and a customer's past transaction behavior to return the number of transactions they are expected to make in a given time period.
ggnbd.ConditionalExpectedTransactions(params, T.star, x, t.x, T.cal)Gamma/Gompertz/NBD parameters - a vector with r, alpha,
b, s and beta in that order.
length of time for which we are calculating the expected number of transactions.
number of repeat transactions in the calibration period T.cal, or a vector of calibration period frequencies.
recency, i.e. length between first and last transaction during calibration period.
length of calibration period, or a vector of calibration period lengths.
Number of transactions a customer is expected to make in a time period of length t, conditional on their past behavior. If any of the input parameters has a length greater than 1, this will be a vector of expected number of transactions.