# Merge Customers Takes two CBT or CBS matrices and ensures that the second one has the same row names as the first. ```r dc.MergeCustomers(data.correct, data.to.correct) ``` ## Arguments - `data.correct`: CBT or CBS with the correct customer IDs as row names. Usually from the calibration period. - `data.to.correct`: CBT or CBS which needs to be fixed (customer IDs inserted). Usually from the holdout period. ## Returns Updated holdout period CBT or CBS. ## Details Care should be taken in using this function. It inserts zero values in all rows that were not in the original holdout period data. This behavior does not cause a problem if using CBT matrices, but will cause a problem if using CBS matrices (for example, the output will report all customers with a holdout period length of zero). However, this particular issue is easily fixed (see examples) and should not cause problems. A work-around to avoid using this function is presented in the example for `dc.BuildCBSFromCBTAndDates` - build the full CBT and only use the columns applying to each particular time period to construct separate CBTs, and from them, CBSs. That is a much cleaner and less error-prone method; however, on occasion the data will not be available in event log format and you may not be able to construct a CBT for both time periods together. ## Examples ```r elog <- dc.ReadLines(system.file("data/cdnowElog.csv", package="BTYD"),2,3,5) elog[,"date"] <- as.Date(elog[,"date"], "%Y%m%d") cutoff.date <- as.Date("1997-09-30") cal.elog <- elog[which(elog[,"date"] <= cutoff.date),] holdout.elog <- elog[which(elog[,"date"] > cutoff.date),] # Create calibration period CBT from cal.elog cal.reach.cbt <- dc.CreateReachCBT(cal.elog) # Create holdout period CBT from holdout.elog holdout.reach.cbt <- dc.CreateReachCBT(holdout.elog) # Note the difference: nrow(cal.reach.cbt) # 2357 customers nrow(holdout.reach.cbt) # 684 customers # Create a "fixed" holdout period CBT, with the same number # of customers in the same order as the calibration period CBT fixed.holdout.reach.cbt <- dc.MergeCustomers(cal.reach.cbt, holdout.reach.cbt) nrow(fixed.holdout.reach.cbt) # 2357 customers # You can verify that the above is correct by turning these into a CBS # (see \code{\link{dc.BuildCBSFromCBTAndDates}} and using # \code{\link{pnbd.PlotFreqVsConditionalExpectedFrequency}}, for example # Alternatively, we can fix the CBS, instead of the CBS: cal.start.dates.indices <- dc.GetFirstPurchasePeriodsFromCBT(cal.reach.cbt) cal.start.dates <- as.Date(colnames(cal.reach.cbt)[cal.start.dates.indices]) cal.end.dates.indices <- dc.GetLastPurchasePeriodsFromCBT(cal.reach.cbt) cal.end.dates <- as.Date(colnames(cal.reach.cbt)[cal.end.dates.indices]) T.cal.total <- rep(cutoff.date, nrow(cal.reach.cbt)) cal.dates <- data.frame(cal.start.dates, cal.end.dates, T.cal.total) # Create calibration period customer-by-sufficient-statistic data frame, # using weeks as the unit of time. cal.cbs <- dc.BuildCBSFromCBTAndDates(cal.reach.cbt, cal.dates, per="week", cbt.is.during.cal.period=TRUE) # Force the calibration period customer-by-sufficient-statistic to only # contain repeat transactions (required by BG/BB and Pareto/NBD models) cal.cbs[,"x"] <- cal.cbs[,"x"] - 1 holdout.start <- cutoff.date+1 holdout.end <- as.Date(colnames(fixed.holdout.reach.cbt)[ncol(fixed.holdout.reach.cbt)]) holdout.dates <- c(holdout.start, holdout.end) # Create holdout period customer-by-sufficient-statistic data frame, # using weeks as the unit of time. holdout.cbs <- dc.BuildCBSFromCBTAndDates(holdout.reach.cbt, holdout.dates, per="week", cbt.is.during.cal.period=FALSE) # Note the difference: nrow(cal.cbs) # 2357 customers nrow(holdout.cbs) # 684 customers # Create a "fixed" holdout period CBS, with the same number # of customers in the same order as the calibration period CBS fixed.holdout.cbs <- dc.MergeCustomers(cal.cbs, holdout.cbs) nrow(fixed.holdout.cbs) # 2357 customers # Furthermore, this function will assign a zero value to all fields # that were not in the original holdout period CBS. Since T.star is the # same for all customers in the holdout period, we should fix that: fixed.holdout.cbs[,"T.star"] <- rep(max(fixed.holdout.cbs[,"T.star"]),nrow(fixed.holdout.cbs)) ```

dc.MergeCustomers function