Sequence Interval Properties

Let’s begin with this textgrid.

from aligned_textgrid import AlignedTextGrid
from aligned_textgrid import Word, Phone

the_dog = AlignedTextGrid(
    textgrid_path="../resources/the_dog.TextGrid", 
    entry_classes=[Word, Phone]
    )
AH0 = the_dog.tier_groups[0].tier_list[1].sequence_list[1]
dog = the_dog.tier_groups[0].tier_list[0].sequence_list[1]

The behavior of `len()`, `in` and iteration

`len()`

If you pass a Sequence Interval to len(), it’ll return the length of its .subset_list.

len(dog)

If a Sequence Interval doesn’t have a .subset_list, then len() will return 0.

len(AH0)

`in`

If you want to check whether a specific sequence interval (the actual object, not just the label) is in the .subset_list of another, you can use in.

AO1 = dog[1]
AO1 in dog

True

AH0 in dog

False

Iteration

A Sequence Interval is iterable over its .subset_list

for segment in dog:
    print(f"{segment.label} is in {segment.inword.label}")

D is in dog
AO1 is in dog
G is in dog

Subset Sequence Information

In addition to the .start, .end and .label information about each Sequence Interval, if it also has a .subset_list, that same information is accessible with .sub_starts, .sub_ends and .sub_labels.

dog.sub_starts

array([0.30829161, 0.41950136, 0.83568509])

dog.sub_ends

array([0.41950136, 0.83568509, 0.96658691])

dog.sub_labels

['D', 'AO1', 'G']

This is a safe way to check if a general phone label is within a word, since just using in on the sequence interval itself checks against specific Sequence Interval objects.

# the label "G" is not a Sequence Interval
"G" in dog

False

"G" in dog.sub_labels

True

Hierarchy Strictness

The hierarchy and precedence structure is very “strict”.

A Sequence Interval a can have no more than one .super_instance
If a.super_instance is B, then a is in B.subset_list.
If a is in B.subset_list, then it is in no other .subset_list.
If a is in B.subset_list, then a.super_instance is B
If a is not in B.subset_list, then a.super_instance is not B
If a.super_instance is not B, then it is not in B.subset_list

Some examples of relationships that cannot be represented are:

Class Strictness

Another source of strictness is the Sequence Interval class. You can get the class of a specific interval with type()

type(AH0)

aligned_textgrid.sequences.word_and_phone.Phone

type(dog)

aligned_textgrid.sequences.word_and_phone.Word

A horizontal strictness of classes is that the .fol and .prev Segment Intervals must be of the same class.

try:
    dog.set_fol(AH0)
except Exception as exc:
    print(exc)

Following segment must be an instance of Word

Each class also defines what its (one and only) .superset_class and .subset_class is. For classes at the top of the hierarchy, there is a reserved Top class, and for classes at the bottom of the hierarchy, there is a reserved Bottom class.

Word.subset_class

aligned_textgrid.sequences.word_and_phone.Phone

Word.superset_class

aligned_textgrid.sequences.word_and_phone.Top_wp

If a Sequence Interval isn’t the right class, it can’t be added to another’s .subset_class or set as its .super_instance.

try:
    AH0.append_subset_list(AO1)
except Exception as exc:
    print(exc)

The subset_class was defined as Bottom_wp, but provided subset_instance was Phone

try:
    AH0.set_super_instance(AO1)
except Exception as exc:
    print(exc)

The superset_class was defined as Word, but provided super_instance was Phone

Reuse

GPLv3

The behavior of len(), in and iteration

len()

in