Extract TextGrid Intervals Using Custom XPtr Predicate

Filter intervals using a user-compiled C++ predicate function. The predicate executes entirely in C++ without any R boundary crossings.

Usage

textgrid_filter_xptr(
  textgrid_xptr,
  tier_number,
  predicate_xptr,
  sound_xptr = NULL,
  extract_sounds = FALSE
)

Arguments

textgrid_xptr

External pointer to TextGrid object

tier_number

Tier number (1-based)

predicate_xptr

External pointer to compiled predicate function created with `RcppXPtrUtils::cppXPtr()`. Signature must be: `bool(const char* label, double start, double end)`

sound_xptr

Optional external pointer to Sound for extraction

extract_sounds

If TRUE and sound_xptr provided, extract Sound parts

Value

List with components: - indices: Integer vector of matching interval indices - labels: Character vector of matching labels - start_times: Numeric vector of start times - end_times: Numeric vector of end times - sounds: List of Sound xptrs (if extract_sounds = TRUE)

Details

**Compiling a custom predicate (requires RcppXPtrUtils):**

“`r # Example: Filter intervals with duration > 0.1s and label starting with 'V' my_pred <- RcppXPtrUtils::cppXPtr( "bool pred(cstr label, double start, double end) { double dur = end - start; return dur > 0.1 && label[0] == 'V'; }", includes = "typedef const char* cstr;" )

result <- textgrid_filter_xptr( textgrid$.xptr, tier = 1, predicate_xptr = my_pred ) “`

See also

[textgrid_extract_intervals_batch()] for simpler string matching

Examples

# \donttest{
if (requireNamespace("RcppXPtrUtils", quietly = TRUE)) {
  tg <- textgrid_create(0, 1, "phones")
  tg$insert_boundary("phones", 0.4)
  tg$insert_boundary("phones", 0.7)
  tg$set_interval_text("phones", 1, "sil")
  tg$set_interval_text("phones", 2, "V")
  tg$set_interval_text("phones", 3, "sil")

  my_pred <- RcppXPtrUtils::cppXPtr(
    "bool pred(cstr label, double start, double end) {
       double dur = end - start;
       return dur > 0.1 && label[0] == 'V';
     }",
    includes = "typedef const char* cstr;"
  )

  result <- textgrid_filter_xptr(tg$.xptr, 1, my_pred)
}
# }