Cross-Validation Forecast (cvforecast)

Forecast time-series by cross-validation method and choose the best models automatically. It contains functions to perform cross-validation and to help decision on the best models according to some goodness of fit statistics, say: MAPE, MAE, RMSE, etc. Ideas like linearity and trend are used to help decision process.

Note: Contains some R functions from the non-official package cv.ts (thanks)

To install code run

devtools::install_github('evandeilton/cvforecast')

Note: There are lots of undocumented code. Use it as your own risk. If you want to help improve, please add comments in the Issues section!

Examples

cvforecast

This is the core function of the package. It computes multiple forecasts by the technique of Cross-Validation. The decision about the best models is based on linearity, trend, fit accuracy as for as residual analysis.

Usage

cvforecast(tsdata, tsControl = cvForecastControl(), fcMethod = NULL, ...)

# Args
tsdata    # data.frame type date-value, ts, mts or xts time series object
tsControl # generic control with several args for the modelling process. 
fcMethod  # accept the forecast method fefined by the user. This argument 
          # can be a string or a list, eg. fcMethod = "fc_ets" or a list as 
          # fcMethod = list("fc_ets", "fc_hws"). If NULL, decision is made
          # automatically.

Run cvforecast example

Define cross validation parameters

require("cvforecast")
myControl <- cvForecastControl(
          minObs = 14,                     # minimum of observations
          stepSize = 10,                   # step size for resampling
          maxHorizon = 30,                 # forecast horizon
          summaryFunc=tsSummary,           # function to sumarize cross-validation accuracy
          cvMethod="MAPE",                 # accuracy statistic choice for decicion
          tsfrequency='day',               # data frequency
          OutlierClean=FALSE,              # clean outlier in data
          dateformat='%d/%m/%Y %H:%M:%S')  # date format is factor or character

Paralell execution improves the processing time

require("doParallel")             # extra package for paralelization
cl <- makeCluster(4, type='SOCK') # 4 is the number os logical cores. Edit as your own!
registerDoParallel(cl)            # register cluster

Load data and convert to 'ts'

data(datasample, package="cvforecast")
tsdata <- ConvertData(datasample[,1:6], 
                    dateformat='%d/%m/%Y %H:%M:%S', tsfrequency = "day",
                    OutType="ts")
table(sapply(tsdata, class))      # check class to confirm conversions
dim(tsdata)

Looping for several forecasts

require("plyr")
FF <- llply(tsdata, function(X) {
          fit <- try(cvforecast(X, myControl))
          if(class(fit) != "try-error") {
          return(fit)
          } else NA
}, .progress = "time")

Summary statistics for first list of best models from the first variable.

summary(FF[[1]])
plot(FF[[1]])
str(FF[[1]])
stopCluster(cl)