"""Utility class for producing a scansion pattern for a Latin pentameter.
Given a line of pentameter, the scan method performs a series of transformation and checks
are performed, and for each one performed successfully, a note is added to the scansion_notes
list so that end users may view the provenance of a scansion.
"""
import re
import cltk.prosody.lat.string_utils as string_utils
from cltk.prosody.lat.metrical_validator import MetricalValidator
from cltk.prosody.lat.scansion_constants import ScansionConstants
from cltk.prosody.lat.scansion_formatter import ScansionFormatter
from cltk.prosody.lat.syllabifier import Syllabifier
from cltk.prosody.lat.verse import Verse
from cltk.prosody.lat.verse_scanner import VerseScanner
__author__ = ["Todd Cook <todd.g.cook@gmail.com>"]
__license__ = "MIT License"
[docs]class PentameterScanner(VerseScanner):
"""The scansion symbols used can be configured by passing a suitable constants class to
the constructor."""
def __init__(
self,
constants=ScansionConstants(),
syllabifier=Syllabifier(),
optional_transform: bool = False,
*args,
**kwargs
):
super().__init__(*args, **kwargs)
self.constants = constants
self.remove_punct_map = string_utils.remove_punctuation_dict()
self.punctuation_substitutions = string_utils.punctuation_for_spaces_dict()
self.metrical_validator = MetricalValidator(constants)
self.formatter = ScansionFormatter(constants)
self.syllabifier = syllabifier
self.optional_transform = optional_transform
self.inverted_amphibrach_re = re.compile(
r"{}\s*{}\s*{}".format(
self.constants.STRESSED,
self.constants.UNSTRESSED,
self.constants.STRESSED,
)
)
self.syllable_matcher = re.compile(
r"[{}]".format(
self.constants.VOWELS
+ self.constants.ACCENTED_VOWELS
+ self.constants.LIQUIDS
+ self.constants.MUTES
)
)
self.SPONDAIC_PENTAMETER = (
self.constants.SPONDEE
+ self.constants.SPONDEE
+ self.constants.STRESSED
+ self.constants.DACTYL
+ self.constants.DACTYL
+ self.constants.OPTIONAL_ENDING
)
self.DACTYLIC_PENTAMETER = (
self.constants.DACTYL
+ self.constants.DACTYL
+ self.constants.STRESSED
+ self.constants.DACTYL
+ self.constants.DACTYL
+ self.constants.OPTIONAL_ENDING
)
[docs] def scan(self, original_line: str, optional_transform: bool = False) -> Verse:
"""
Scan a line of Latin pentameter and produce a scansion pattern, and other data.
:param original_line: the original line of Latin verse
:param optional_transform: whether or not to perform i to j transform for syllabification
:return: a Verse object
>>> scanner = PentameterScanner()
>>> print(scanner.scan('ex hoc ingrato gaudia amore tibi.'))
Verse(original='ex hoc ingrato gaudia amore tibi.', scansion='- - - - - - U U - U U U ', meter='pentameter', valid=True, syllable_count=12, accented='ēx hōc īngrātō gaudia amōre tibi.', scansion_notes=['Spondaic pentameter'], syllables = ['ēx', 'hoc', 'īn', 'gra', 'to', 'gau', 'di', 'a', 'mo', 're', 'ti', 'bi'])
>>> print(scanner.scan(
... "in vento et rapida scribere oportet aqua.").scansion) # doctest: +NORMALIZE_WHITESPACE
- - - U U - - U U - U U U
"""
verse = Verse(original_line, meter="pentameter")
# replace punctuation with spaces
line = original_line.translate(self.punctuation_substitutions)
# conservative i to j
line = self.transform_i_to_j(line)
working_line = self.elide_all(line)
working_line = self.accent_by_position(working_line)
syllables = self.syllabifier.syllabify(working_line)
if optional_transform:
working_line = self.transform_i_to_j_optional(line)
working_line = self.elide_all(working_line)
working_line = self.accent_by_position(working_line)
syllables = self.syllabifier.syllabify(working_line)
verse.scansion_notes += [self.constants.NOTE_MAP["optional i to j"]]
verse.working_line = working_line
verse.syllable_count = self.syllabifier.get_syllable_count(syllables)
verse.syllables = syllables
if verse.syllable_count < 12:
verse.valid = False
verse.scansion_notes += [self.constants.NOTE_MAP["< 12p"]]
return verse
stresses = self.flag_dipthongs(syllables)
syllables_wspaces = string_utils.to_syllables_with_trailing_spaces(
working_line, syllables
)
offset_map = self.calc_offset(syllables_wspaces)
for idx, syl in enumerate(syllables):
for accented in self.constants.ACCENTED_VOWELS:
if accented in syl:
stresses.append(idx)
# first syllable is always long in Pentameter
stresses.append(0)
# second to last syllable is always long
stresses.append(verse.syllable_count - 2)
verse.scansion = self.produce_scansion(stresses, syllables_wspaces, offset_map)
if len(
string_utils.stress_positions(self.constants.STRESSED, verse.scansion)
) != len(set(stresses)):
verse.valid = False
verse.scansion_notes += [self.constants.NOTE_MAP["invalid syllables"]]
return verse
if self.metrical_validator.is_valid_pentameter(verse.scansion):
verse.scansion_notes += [self.constants.NOTE_MAP["positionally"]]
return self.assign_candidate(verse, verse.scansion)
# identify some obvious and probably choices based on number of syllables
if verse.syllable_count == 12: # produce spondees where possible
candidate = self.make_spondaic(verse.scansion)
verse.scansion_notes += [self.constants.NOTE_MAP["12p"]]
return self.assign_candidate(verse, candidate)
if verse.syllable_count == 14: # produce spondees where possible
candidate = self.make_dactyls(verse.scansion)
verse.scansion_notes += [self.constants.NOTE_MAP["14p"]]
return self.assign_candidate(verse, candidate)
if verse.syllable_count > 14:
verse.valid = False
verse.scansion_notes += [self.constants.NOTE_MAP["> 14"]]
return verse
smoothed = self.correct_first_two_dactyls(verse.scansion)
if verse.scansion != smoothed:
verse.scansion_notes += [self.constants.NOTE_MAP["invalid start"]]
verse.scansion = smoothed
stresses += string_utils.differences(verse.scansion, smoothed)
if self.metrical_validator.is_valid_pentameter(verse.scansion):
return self.assign_candidate(verse, verse.scansion)
smoothed = self.correct_penultimate_dactyl_chain(verse.scansion)
if verse.scansion != smoothed:
verse.scansion_notes += [
self.constants.NOTE_MAP["penultimate dactyl chain"]
]
verse.scansion = smoothed
stresses += string_utils.differences(verse.scansion, smoothed)
if self.metrical_validator.is_valid_pentameter(verse.scansion):
return self.assign_candidate(verse, verse.scansion)
candidates = self.metrical_validator.closest_pentameter_patterns(verse.scansion)
if candidates is not None:
if (
len(candidates) == 1
and len(verse.scansion.replace(" ", "")) == len(candidates[0])
and len(string_utils.differences(verse.scansion, candidates[0])) == 1
):
tmp_scansion = self.produce_scansion(
string_utils.differences(verse.scansion, candidates[0]),
syllables_wspaces,
offset_map,
)
if self.metrical_validator.is_valid_pentameter(tmp_scansion):
verse.scansion_notes += [self.constants.NOTE_MAP["closest match"]]
return self.assign_candidate(verse, tmp_scansion)
# if the line doesn't scan "as is", it may scan if the optional i to j transformations
# are made, so here we set them and try again.
if self.optional_transform and not verse.valid:
return self.scan(original_line, optional_transform=True)
verse.accented = self.formatter.merge_line_scansion(
verse.original, verse.scansion
)
return verse
[docs] def make_spondaic(self, scansion: str) -> str:
"""
If a pentameter line has 12 syllables, then it must start with double spondees.
:param scansion: a string of scansion patterns
:return: a scansion pattern string starting with two spondees
>>> print(PentameterScanner().make_spondaic("U U U U U U U U U U U U"))
- - - - - - U U - U U U
"""
mark_list = string_utils.mark_list(scansion)
vals = list(scansion.replace(" ", ""))
new_vals = self.SPONDAIC_PENTAMETER[:-1] + vals[-1]
corrected = "".join(new_vals)
new_line = list(" " * len(scansion))
for idx, car in enumerate(corrected):
new_line[mark_list[idx]] = car
return "".join(new_line)
[docs] def make_dactyls(self, scansion: str) -> str:
"""
If a pentameter line has 14 syllables, it starts and ends with double dactyls.
:param scansion: a string of scansion patterns
:return: a scansion pattern string starting and ending with double dactyls
>>> print(PentameterScanner().make_dactyls("U U U U U U U U U U U U U U"))
- U U - U U - - U U - U U U
"""
mark_list = string_utils.mark_list(scansion)
vals = list(scansion.replace(" ", ""))
new_vals = self.DACTYLIC_PENTAMETER[:-1] + vals[-1]
corrected = "".join(new_vals)
new_line = list(" " * len(scansion))
for idx, car in enumerate(corrected):
new_line[mark_list[idx]] = car
return "".join(new_line)
[docs] def correct_penultimate_dactyl_chain(self, scansion: str) -> str:
"""
For pentameter the last two feet of the verse are predictable dactyls,
and do not regularly allow substitutions.
:param scansion: scansion line thus far
:return: corrected line of scansion
>>> print(PentameterScanner().correct_penultimate_dactyl_chain(
... "U U U U U U U U U U U U U U"))
U U U U U U U - U U - U U U
"""
mark_list = string_utils.mark_list(scansion)
vals = list(scansion.replace(" ", ""))
n_vals = (
vals[:-7] + [self.constants.DACTYL + self.constants.DACTYL] + [vals[-1]]
)
corrected = "".join(n_vals)
new_line = list(" " * len(scansion))
for idx, car in enumerate(corrected):
new_line[mark_list[idx]] = car
return "".join(new_line)