Helper function for as.data.frame.fitted, forecast. Converts predictive array to data.frame.
.pred_array_to_df(arr, type = "backcast", param = "var")
data.frame. Columns: period, type (backcast, forecast), param (var, mean, cor), TS (which time series, or which correlation for param = cor), summary columns.
Array to convert into data frame.
String. "backcast" or "forecast".
String. "var", "mean", or "cor".
Stephen R. Martin