Initialize a new PPM counter Train on a single sequence (incremental LTM update)
ppidyom-class.RdInitialize a new PPM counter Train on a single sequence (incremental LTM update)
Arguments
- x
Character vector sequence
- model_type
Model type: "stm", "ltm", "both", "ltm+", "both+"
- ppm_type
"interpolation" or "backoff"
- stm_lambda
escape or discount function for STM (default = "C")
- ltm_lambda
escape or discount function for LTM (default = "C")
- b
Bias parameter for relative-entropy weighting (used for + models)
- idyom_base
Logical. If TRUE, use IDyOM-compatible order-(-1) base distribution: 1/|alphabet| when exclusion=FALSE, shrinking denominator when exclusion=TRUE. If FALSE (default), always use the shrinking denominator (matches Harrison's ppm package). See vignette("implementation-discrepancy") for details.
Note: the constructor flag `ltm_start_token` controls whether LTM counts include beginning-of-sequence positions (TRUE, default) or skip them (FALSE, IDyOM-compatible). See vignette("implementation-discrepancy").