Working with discourse-level annotations

In the previous sections, we have created linguistic annotations for plain text using various natural language processing techniques.

In this section, we learn how to use pre-existing linguistic annotations, focusing especially on annotations that target phenomena above the level of a clause.

After reading through this section, you should:

  • know the basics of the CoNLL-U annotation schema

  • know how to create a spaCy Doc object manually

  • know how to annotate Spans in a Doc object using SpanGroups

  • know how to load CoNLL-U annotated corpora into spaCy

Introducing the CoNLL-U annotation schema

CoNLL-X is an annotation schema for describing linguistic features across diverse languages (Buchholz and Marsi 2006), which was originally developed to facilitate collaboration on so-called shared tasks in research on natural language processing (see e.g. Nissim et al. 2017).

CoNLL-U is a further development of this annotation schema for the Universal Dependencies formalism, which was introduced in Part III. This annotation schema is commonly used for distributing linguistic corpora in projects that build on this formalism, but it is not uncommon to see other projects use CoNLL-U as well.

In addition to numerous modern languages, one can find, for example, CoNLL-U annotated corpora for ancient languages such Akkadian (Luukko et al. 2020) and Coptic (Zeldes and Abrams 2018).

The components of the CoNLL-U annotation schema

CoNLL-U annotations are distributed as plain text files (see Part II).

The annotation files contain three types of lines: comment lines, word lines and blank lines.

Comment lines precede word lines and start with a hash character (#). These lines can be used to provide metadata about the word lines that follow.

Each word line contains annotations for a single word or token. Larger linguistic units are represented by subsequent word lines.

The annotations for a word line are provided using the following fields, each separated by a tabulator character:

ID	FORM	LEMMA	UPOS	XPOS	FEATS	HEAD	DEPREL	DEPS	MISC
  1. ID: Index of the word in sequence

  2. FORM: The form of a word or punctuation symbol

  3. LEMMA: Lemma or the base form of a word

  4. UPOS: Universal part-of-speech tag

  5. XPOS: Language-specific part-of-speech tag

  6. FEATS: Morphological features

  7. HEAD: Syntactic head of the current word

  8. DEPREL: Universal dependency relation to the HEAD

  9. DEPS: Enhanced dependency relations

  10. MISC: Any additional annotations

Finally, a blank line after word lines is used to separate sentences.

Interacting with CoNLL-U annotations in Python

To explore CoNLL-U annotations using Python, let’s start by importing conllu, a small library for parsing CoNLL-U annotations into various data structures native to Python.

# Import the conllu library
import conllu

We then open a plain text file with annotations in the CoNLL-U format from the Georgetown University Multilayer Corpus (GUM; see Zeldes 2017), read its contents using the read() method and store the result under the variable annotations.

# Open the plain text file for reading; assign under 'data'
with open('data/GUM_whow_parachute.conllu', mode="r", encoding="utf-8") as data:
    
    # Read the file contents and assign under 'annotations'
    annotations = data.read()

# Check the type of the resulting object
type(annotations)
str

This gives us a Python string object. Let’s print out the first 1000 characters of this string.

# Print the first 1000 characters of the string under 'annotations'
print(annotations[:1000])
# newdoc id = GUM_whow_parachute
# sent_id = GUM_whow_parachute-1
# text = How to Cope With a Double Parachute Failure
# s_type = inf
1	How	how	SCONJ	WRB	PronType=Int	3	mark	_	Discourse=preparation:1->11
2	to	to	PART	TO	_	3	mark	_	_
3	Cope	Cope	VERB	VB	VerbForm=Inf	0	root	_	_
4	With	with	ADP	IN	_	8	case	_	_
5	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	Entity=(event-1
6	Double	double	ADJ	JJ	Degree=Pos	8	amod	_	_
7	Parachute	parachute	NOUN	NN	Number=Sing	8	compound	_	Entity=(object-2)
8	Failure	failure	NOUN	NN	Number=Sing	3	obl	_	Entity=event-1)

# sent_id = GUM_whow_parachute-2
# text = While skydiving, it is possible (yet extremely unlikely) that both your primary and reserve parachutes will malfunction, leaving you with no method of reducing your velocity.
# s_type = decl
1	While	while	SCONJ	IN	_	2	mark	_	Discourse=circumstance:2->3
2	skydiving	skydiving	NOUN	NN	Number=Sing	6	advcl	_	Entity=(event-3)|SpaceAfter=No
3	,	,	PUNCT	,	_	2	punct	_	_
4	it	it	PRON	PRP	Case=Nom|Gender=Neut|Num

As you can see, the string object contains comment lines (prefixed with a hash), followed by word lines that contain the annotations for the fields introduced above.

An underscore _ is used to indicate fields with empty or missing values on the word lines.

In the GUM corpus, the final field MISC contains values such as Discourse and Entity that provide annotations for discourse relations and entities such as events and objects.

Here the question is: how to extract all this information programmatically from a Python string object, which we cannot access like a list or a dictionary?

This is where the conllu module steps in, because its parse() function is capable of extracting information from CoNLL-U formatted strings.

# Use the parse() function to parse the annotations; store under 'sentences'
sentences = conllu.parse(annotations)

The parse() function returns a Python list populated by TokenList objects. This object type is native to the conllu library.

Let’s examine the first item in the list sentences.

sentences[0]
TokenList<How, to, Cope, With, a, Double, Parachute, Failure>

This gives us a TokenList object.

To start with, the information contained in the hash-prefixed comment lines in the CoNLL-U schema is provided under the metadata attribute.

# Get the metadata for the first item in the list
sentences[0].metadata
{'newdoc id': 'GUM_whow_parachute',
 'sent_id': 'GUM_whow_parachute-1',
 'text': 'How to Cope With a Double Parachute Failure',
 's_type': 'inf'}

This shows how the GUM corpus uses the comment lines to provide four types of metadata for each sentence: newdoc_id for document identifier, sent_id for sentence identifier, text for plain text and s_type for the grammatical mood of the sentence (Zeldes & Simonson 2017: 69).

Superficially, the object stored under the metadata attribute looks like a Python dictionary, but the object is actually a conllu Metadata object.

This object, however, behaves just like a Python dictionary in the sense that it consists of key and value pairs, which are accessed just like those in a dictionary.

To exemplify, to retrieve the sentence type (or its grammatical mood), simply use the key s_type to access the Metadata object.

# Get the sentence type under 's_type'
sentences[0].metadata['s_type']
'inf'

This returns the string inf, which corresponds to infinitive.

Coming back to the TokenList object, as the name suggest, the items in a TokenList consist of individual Token objects.

Let’s access the first Token object [0] in the first TokenList object [0] under sentences.

# Get the first token in the first sentence
sentences[0][0]
{'id': 1,
 'form': 'How',
 'lemma': 'how',
 'upos': 'SCONJ',
 'xpos': 'WRB',
 'feats': {'PronType': 'Int'},
 'head': 3,
 'deprel': 'mark',
 'deps': None,
 'misc': {'Discourse': 'preparation:1->11'}}

Just like the TokenList above, the Token is a dictionary-like object with keys and values.

The dictionary under the key misc holds information about discourse relations, which describe how parts of a text relate to each other using a formalism named Rhetorical Structure Theory (Mann & Thompson 1988).

In this case, the annotation states that a discourse relation named preparation holds between units 1 and 11.

These units and their identifiers do not correspond words or sentences in the document, but to elementary discourse units.

These elementary discourse units define an additional level of segmentation, which seeks to define units of discourse that are placed in various relations to one another.

In classical Rhetorical Structure Theory, these elementary discourse units (abbreviated EDU) often correspond to clauses, but this is not a requirement set by the theory.

Adding discourse-level annotations to Doc objects

As pointed out above, the GUM corpus uses the key Discourse in the misc field to indicate the beginning of an elementary discourse unit.

By tracking Token objects with these properties, we can identify the boundaries of elementary discourse units, which are not necessarily aligned with sentences in the TokenList object.

We can keep track of these boundaries by counting Tokens and noting down the indices of Tokens that contain the Discourse key under misc.

Let’s set up a variable for counting the Tokens and several lists for holding the information that we will collect from the TokenList objects.

# Set up a variable with value 0 that we will use for counting
# the Tokens that we process
counter = 0

# We use these lists to keep track of sentences, discourse units
# and the relations that hold between them.
discourse_units = []
sent_types = []
relations = []

# Set up placeholder lists for the information that we will extract
# from the CoNLL-U annotations. These lists will be used to create 
# a spaCy Doc object below.
words = []
spaces = []
sent_starts = []

We use the value stored under the variable counter to keep track of the boundaries for elementary discourse units as we loop over the TokenList objects stored in the list sentences.

# Loop over each TokenList object
for sentence in sentences:
    
    # When we begin looping over a new sentence, set the value of
    # the variable 'is_start' to True. This marks the beginning of
    # a sentence.
    is_start = True
    
    # Add the current sentence type to the list 'sent_types'
    sent_types.append(sentence.metadata['s_type'])
        
    # Proceed to loop over the Tokens in the current TokenList object
    for token in sentence:
        
        # Use the key 'form' to retrieve the word form for the 
        # Token and append it to the placeholder list 'words'.
        words.append(token['form'])
        
        # Check if this Token begins a sentence by evaluating whether
        # the variable 'is_start' is True. 
        if is_start:
            
            # If the Token starts a sentence, add value True to the list
            # 'sent_starts'. Note the missing quotation marks: this is a 
            # Boolean value (True / False).
            sent_starts.append(True)
            
            # Set the variable 'is_start' to False until the next sentence
            # starts and the variable is set to True again.
            is_start = False
        
        # If the variable 'is_start' is False, execute the code block below
        else:
            
            # Append value 'False' to the list 'sent_starts'
            sent_starts.append(False)
        
        # Check if the key 'misc' contains anything, and if the key
        # holds the value 'Discourse', proceed to the code block below.
        if token['misc'] is not None and 'Discourse' in token['misc']:
            
            # The presence of the key 'Discourse' indicates the beginning
            # of a new elementary discourse unit; add its index to the list
            # 'discourse_units'.
            discourse_units.append(counter)
            
            # Unpack the relationship definition; start by splitting the
            # relation name from the elementary discourse units. Assign
            # the resulting objects under 'relation' and 'edus'.
            relation, edus = token['misc']['Discourse'].split(':')
            
            # Try to split the relation annotation into two parts
            try:
                
                # Split at the '->' string and assign to 'source'
                # and 'target', respectively.
                source, target = edus.split('->')
                
                # Deduct -1 from both 'source' and 'target', because 
                # the identifiers used in the GUM corpus are not 
                # zero-indexed, but our spaCy Spans that correspond to
                # elementary discourse units will be. Also cast the
                # numbers into integers (these are originally strings!).
                source, target = int(source) - 1, int(target) - 1
            
            # The root node of the RST tree will not have a target,
            # which raises a ValueError since there is only one item.
            except ValueError:
                
                # Assign the first item in 'edus' to 'source' and set
                # target to None. 
                source, target = edus[0], None
                
                # Deduct -1 from 'source' as explained above.
                source = int(source) - 1 
                
            # Compile the relation definition into a three tuple and
            # append to the list 'relations'.
            relations.append((relation, source, target))
            
        # Check if the current Token is followed by a whitespace. If this is
        # not the case, e.g. for the Token at the end of a TokenList, this
        # information is available under the 'misc' key.
        if token['misc'] is not None and 'SpaceAfter' in token['misc']:
            
            # If the 'misc' key holds a dictionary with the key 'SpaceAfter'
            # with a value 'No', proceed below
            if token['misc']['SpaceAfter'] == 'No':
                
                # Append the Boolean value 'False' to the list 'spaces'.
                spaces.append(False)
            
        # If the 'SpaceAfter' key is not found under 'misc', the token is followed
        # by a space.
        else:

            # Append True to the list of spaces
            spaces.append(True)
        
        # Update the counter as we finish looping over a Token object
        # by adding +1 to its value.
        counter += 1

This collects the information needed for creating a spaCy Doc object, together with the discourse-level annotations that we will add to the Doc object afterwards.

As the example above shows, collecting this kind of information from annotations requires one to be familiar with the annotation schema, particularly in terms of how additional information stored under the field misc for Tokens or in the metadata for TokenLists, in order to catch any potential errors.

Moving ahead, we typically create spaCy Doc objects by passing some text to a Language object, as shown in Part II, which takes care of operations such as tokenization.

In this case, however, we need to preserve the tokens defined in the CoNLL-U annotations, because this information is needed to align the discourse-level annotations correctly for both sentences and elementary discourse units.

In other words, we cannot take the risk that spaCy tokenises the text differently, because this would result in misaligned annotations for sentences and elementary discourse units.

Thus we create a spaCy Doc object manually by importing the Doc class from spaCy’s tokens submodule. We also load a small language model for English and store it under the variable nlp.

# Import the Doc class and the spaCy library
from spacy.tokens import Doc
import spacy

# Load a small language model for English; store under 'nlp'
nlp = spacy.load('en_core_web_sm')

We can now use the Doc class to create Doc objects manually by providing the information collected in the lists words, spaces and sent_starts as input to the newly-created Doc object.

Let’s take a quick look at the information we collected into the lists.

# Loop over the first 15 items in lists 'words', 'spaces' and 'sent_starts'.
# Use the zip() function to fetch items from these lists simultaneously.
for word, space, sent_start in zip(words[:15], spaces[:15], sent_starts[:15]):
    
    # Print out the current item in each list
    print(word, space, sent_start)
How True True
to True False
Cope True False
With True False
a True False
Double True False
Parachute True False
Failure True False
While True True
skydiving False False
, True False
it True False
is True False
possible True False
( False False

In addition, we must pass a Vocabulary object to the vocab argument to associate the Doc with a given language, as normally this information is assigned by the Language object.

# Create a spaCy Doc object "manually"; assign under the variable 'doc'
doc = Doc(vocab=nlp.vocab, 
          words=words, 
          spaces=spaces,
          sent_starts=sent_starts
          )

This gives us a Doc object with pre-defined Tokens and sentence boundaries.

# Retrieve Tokens up to index 15 from the Doc object
doc[:15]
How to Cope With a Double Parachute Failure While skydiving, it is possible (

As you can see, spaCy has successfully assigned the words in words to Token objects, while the Boolean values in spaces determine whether a Token is followed by a space or not.

The sentence boundaries in sent_starts, in turn, are used to define the sentences under the attribute sents of a Doc object.

# Retrieve the first five sentences in the Doc object
list(doc.sents)[:5]
[How to Cope With a Double Parachute Failure,
 While skydiving, it is possible (yet extremely unlikely) that both your primary and reserve parachutes will malfunction, leaving you with no method of reducing your velocity.,
 In the vast majority of cases, this will not occur;,
 nevertheless, in this event these coping strategies may assist.,
 Steps]

However, because we discarded the linguistic information contained in the CoNLL-U annotations, the attributes of the Token objects in our Doc object are empty.

Let’s fetch the fine-grained part-of-speech tag for the first Token in the Doc object.

# Get the fine-grained part-of-speech tag for Token at index 0
doc[0].tag_
''

As this shows, the tag_ attribute of the Token does not exist.

We cannot pass our Doc object doc directly to the language model under nlp for additional annotations, but we need to create these manually by providing the Doc separately to various components of the natural language processing pipeline in the Language object.

These components are accessible under the attribute pipeline, as we learned in Part II.

Let’s loop over the components of the pipeline and apply them to the Doc object under doc.

# Loop over the name / component pairs under the 'pipeline' attribute
# of the Language object 'nlp'.
for name, component in nlp.pipeline:
    
    # Use a formatted string to print out the 'name' of the component
    print(f"Now applying component {name} ...")
    
    # Feed the existing Doc object to the component and store the updated
    # annotations under the variable of the same name ('doc').
    doc = component(doc)
Now applying component tok2vec ...
Now applying component tagger ...
Now applying component parser ...
Now applying component attribute_ruler ...
Now applying component lemmatizer ...
Now applying component ner ...

If we now examine the attribute tag_ of the first Token object, the fine-grained part-of-speech tag has been added to the Token.

# Get the fine-grained part-of-speech tag for Token at index 0
doc[0].tag_
'WRB'

Furthermore, we now have access to additional linguistic annotations produced by spaCy, such as noun phrases under the attribute noun_chunk.

# Get the first five noun phrases in the Doc object
list(doc.noun_chunks)[:5]
[a Double Parachute Failure,
 it,
 both your primary and reserve parachutes,
 you,
 no method]

Our manually-defined sentence boundaries, however, remain the same, although normally spaCy uses the syntactic dependencies to segment text into sentences!

# Get the first five sentences in the Doc object
list(doc.sents)[:5]
[How to Cope With a Double Parachute Failure,
 While skydiving, it is possible (yet extremely unlikely) that both your primary and reserve parachutes will malfunction, leaving you with no method of reducing your velocity.,
 In the vast majority of cases, this will not occur;,
 nevertheless, in this event these coping strategies may assist.,
 Steps]

Now that we have a fully-annotated Doc object, we can proceed to enhance this object with discourse-level annotations collected from the CoNLL-U annotations, which are stored in the lists discourse_units, sent_types and relations.

Adding information on sentence mood

Let’s start by adding information on sentence type to the Doc object, which we collected into the list sent_types.

These annotations provide information on grammatical mood of the sentence, as exemplified by categories such as infinitive, declarative and imperative.

Let’s check out the first ten items in the list sent_types.

# Print out the 
sent_types[:10]
['inf', 'decl', 'decl', 'decl', 'frag', 'imp', 'decl', 'imp', 'imp', 'imp']

These are the categories that we want to associate with each sentence in the Doc object.

Before proceeding, let’s make sure that the lengths for the sent_types list and the sentences in the Doc object match each other.

# Check the length of sentence type information and 
# the number of sentences in the Doc object.
len(sent_types) == len(list(doc.sents))
True

In spaCy, information on grammatical mood of a sentence is best represented using a custom attribute for a Span object, as these objects consist of sequences of Token objects within a Doc.

Actually, the sentences available under the attribute sents of a Doc object, whose mood we want to describe, are Span objects.

# Print out the first sentence in the Doc and its type()
list(doc.sents)[0], type(list(doc.sents)[0])
(How to Cope With a Double Parachute Failure, spacy.tokens.span.Span)

To assign information on grammatical mood to these Spans, let’s continue by importing two classes: SpanGroup and Span.

# Import the SpanGroup and Span classes from spaCy
from spacy.tokens.span_group import SpanGroup
from spacy.tokens import Span

As instructed in Part II, the Span class is needed to register a custom attribute for storing information on grammatical mood for Span objects.

The SpanGroup, in turn, is a class that allows defining groups of Span objects, which can be stored under the spans attribute of a Doc object.

Let’s create a SpanGroup object that contains Spans that correspond to the sentences under the sents attribute in the Doc object.

This requires three arguments: doc, which takes the Doc object that contains the Spans to be grouped, a name for the SpanGroup and spans, a list of Span objects in the Doc object referred to in doc.

# Create a SpanGroup from Spans contained in the Doc object 'doc', which
# was created from the CoNLL-U annotations. These Spans correspond to
# sentences, whose boundaries we defined manually. Assign to variable
# 'sent_group'.
sent_group = SpanGroup(doc=doc, name="sentences", spans=list(doc.sents))

This creates a SpanGroup object, which we can then assign to the spans attribute of the Doc object.

# Assign the SpanGroup to the 'spans' attribute of the Doc object under the
# key 'sentences'.
doc.spans['sentences'] = sent_group

Next, we register the custom attribute mood with the Span class, and assign it with the default value None.

# Register the custom attribute 'mood' with the Span class
Span.set_extension('mood', default=None)

We then use Python’s zip() function to iterate over pairs of items in the list sent_types and the SpanGroup object stored under the key sentences in the spans attribute of the Doc object.

During each loop, we refer to the sentence type information from the sent_types list as mood and to the Span object as span.

We then assign the value stored under the variable mood to the custom attribute mood of the Span object under span.

Remember that spaCy uses an underscore _ as a dummy attribute for user-defined attributes, as explained in Part II.

# Loop over pairs of items from the list and the SpanGroup
for mood, span in zip(sent_types, doc.spans['sentences']):
    
    # Assign the value of 'mood' under the custom attribute
    # with the same name, which belongs to the Span object.
    span._.mood = mood

This adds information on grammatical mood under the custom attribute mood of each Span object.

Let’s retrieve the sentence stored under index 8 and information on its mood.

# Retrieve information on grammatical mood for sentence at index 8
doc.spans['sentences'][8], doc.spans['sentences'][8]._.mood
(If both your primary and reserve chutes have malfunctioned, signal immediately to a fellow jumper who has not yet deployed their chute, waving your arms and signalling that your own is not functional.,
 'imp')

As you can see, this returns a sentence with imperative mood, which suggests that this information has been successfully added to the Doc object.

Adding information on discourse relations

For defining the boundaries of elementary discourse units, we need to use the information contained in the list discourse_units.

# Check the first 10 items in the list 'discourse_units'
discourse_units[:10]
[0, 8, 11, 14, 19, 29, 34, 39, 51, 62]

We created this list above by noting down the index of each Token that marked the beginning of an elementary discourse unit.

What we need to do next is to use these indices to get slices of the Doc object, that is, Span objects that correspond to the discourse units.

We can do this by looping over the numbers stored in the discourse_units list and use them for determining the beginning and end of a Span as shown below.

# Create a placeholder list to hold slices of the Doc object that correspond
# to discourse units.
edu_spans = []

# Proceed to loop over discourse unit boundaries using Python's range() function.
# This will give us numbers, which we use to index the 'discourse_units' list that
# contains the indices that mark the beginning of a discourse unit.
for i in range(len(discourse_units)):
    
    # Try to execute the following code block
    try:
        
        # Get the current item in the list 'discourse_units' and the next item; assign
        # under variables 'start' and 'end'.
        start, end = discourse_units[i], discourse_units[i + 1]
    
    # If the next item is not available, because we've reached the final item in the list,
    # this will raise an IndexError, which we catch here.
    except IndexError:
        
        # Assign the start of the discourse unit as usual, set the length of the Doc 
        # object as the value for 'end' to mark the end point of the discourse unit. 
        start, end = discourse_units[i], len(doc)

    # Use the 'start' and 'end' variables to slice the Doc object; append the
    # resulting Span object to the list 'edu_spans'.
    edu_spans.append(doc[start:end])

This gives us a list of Span objects that correspond to the elementary discourse units.

# Get the first seven Spans in the list 'edu_spans'
edu_spans[:7]
[How to Cope With a Double Parachute Failure,
 While skydiving,,
 it is possible,
 (yet extremely unlikely),
 that both your primary and reserve parachutes will malfunction,,
 leaving you with no method,
 of reducing your velocity.]

As you can see, the elementary discourse units are not necessary aligned with sentences.

Next, we must register additional custom attributes for the Span object that will hold the annotations for discourse relations.

# Register three custom attributes for Span objects, which correspond to
# elementary discourse unit id, the id of the element acting as the target,
# and the name of the relation.
Span.set_extension('edu_id', default=None)
Span.set_extension('target_id', default=None)
Span.set_extension('relation', default=None)

The attribute edu_id will hold the unique identifier for each elementary discourse unit, whereas the target_id attribute contains the identifier of the discourse unit that the current discourse unit is related to.

The relation attribute, in turn, contains the name of the discourse relation that holds between the participating units.

Just as above, we use the SpanGroup object to store these Spans under the key edus of the spans attribute.

# Create a SpanGroup object from the Spans in the 'edu_spans' list
edu_group = SpanGroup(doc=doc, name="edus", spans=edu_spans)

# Assign the SpanGroup under the key 'edus'
doc.spans['edus'] = edu_group

Next, we populate the custom attributes of these Span objects with information stored in the list relations.

When extracting information from the CoNLL-U annotations, we collected information on discourse relations into three-tuples in which the first item gives the relation, whereas the remaining two items give the identifiers for elementary discourse units participating in the relation. The first identifier determines the “source” of the relation whereas the second is the “target”.

# Print out the first five relation definitions in the list 'relations'
relations[:5]
[('preparation', 0, 10),
 ('circumstance', 1, 2),
 ('background', 2, 8),
 ('concession', 3, 2),
 ('same-unit', 4, 2)]

We now proceed to loop over the list relations and assign this information into the Spans in the SpanGroup under the key edus of the spans attribute.

# Loop over each three-tuple in the list 'relations'
for relation in relations:
    
    # Split the three-tuple into three variables
    rel_name, source, target = relation[0], relation[1], relation[2]
    
    # Use the identifier under 'source' to index the Span objects under
    # the key 'edus'. Then access the custom attributes and set the values
    # for 'edu_id', 'target_id' and 'relation'.
    doc.spans['edus'][source]._.edu_id = source
    doc.spans['edus'][source]._.target_id = target
    doc.spans['edus'][source]._.relation = rel_name

This stores the information on the discourse relations under the custom attributes.

We can examine the result by retrieving the custom attribute relation for the Span under index 1 in the Doc object doc.

# Retrieve the custom attribute 'relation' for the Span at index 1
doc.spans['edus'][1]._.relation
'circumstance'

This indicates that this Span participates in a circumstantial relation with another unit, whose identifier is stored under the custom attribute target_id.

Because the attribute target_id contains an integer that identifies another discourse unit, we can use this value to index the SpanGroup object under doc.spans['edus'] to retrieve the target.

# Get the Span at index 1 and the Span referred to by its 'target_id' attribute
doc.spans['edus'][1], doc.spans['edus'][doc.spans['edus'][1]._.target_id]
(While skydiving,, it is possible)

This gives us the two elementary discourse units participating in the “circumstance” relation.

Converting CoNLL-U annotations into Doc objects

If you do not need to enrich spaCy objects with additional information, but simply wish to convert CoNLL-U annotations into Doc objects, spaCy provides a convenience function, conllu_to_docs(), for converting CoNLL-U annotated data into spacy Doc objects.

Let’s start by importing the function from the training submodule, as this function is mainly used for loading CoNLL-U annotated data for training language models. We also import the class for the Doc object.

# Import the 'conllu_to_docs' function and the Doc class
from spacy.training.converters import conllu_to_docs
from spacy.tokens import Doc

The conllu_to_docs() function takes a Python string object as input.

We pass the string object annotations that contains CoNLL-U annotations to the function, and set the argument no_print to True to prevent the conllu_to_docs() function from printing status messages.

The function returns a Python generator object, which we must cast into a list to examine its contents.

# Provide the string object under 'annotations' to the 'conllu_to_docs' function. 
# Set 'no_print' to True and cast the result into a Python list; store under 'docs'.
docs = list(conllu_to_docs(annotations, no_print=True))

# Get the first two items in the resulting list
docs[:2]
[How to Cope With a Double Parachute Failure While skydiving, it is possible (yet extremely unlikely) that both your primary and reserve parachutes will malfunction, leaving you with no method of reducing your velocity. In the vast majority of cases, this will not occur; nevertheless, in this event these coping strategies may assist. Steps Remain calm. This may seem obvious, but deep, even breathing (despite the rushing slipstream) and controlling your heart-rate are essential to your continued survival. Entreat assistance. If both your primary and reserve chutes have malfunctioned, signal immediately to a fellow jumper who has not yet deployed their chute, waving your arms and signalling that your own is not functional. If this is a solo jump, then skip to step 6. ,
 Prepare for deployment. After linking arms with your fellow jumper, you will need to hook your arms through their chest strap, or through both sides of the front of their harness, as far as you can, then grab onto your own strap. Deploy. The shock of the chute deployment will be intense. The G-forces will multiply your body weight, making it impossible to hold on; this is why hooking your arms through the harness is essential. It is likely that the shock will dislocate or break both your arms; nevertheless this is a small price to pay for your life. Prepare for impact. If your companion's canopy has successfully opened, then both your chances of survival have dramatically increased. ]

This gives us a list with Doc objects. By default, the conllu_to_docs() function groups every ten sentences in the CoNLL-u files into a single spaCy object.

This, however, is not an optimal solution, as having every document its own Doc object would make more sense rather than an arbitrary grouping.

To do so, we can use the from_docs() method of the Doc object to combine the Doc objects in the list docs.

# Combine Doc objects in the list 'docs' into a single Doc; assign under 'doc'
doc = Doc.from_docs(docs)

# Check variable type and length
type(doc), len(doc)
(spacy.tokens.doc.Doc, 890)

This gives us a single spaCy Doc object with 890 Tokens.

If we loop over the first eight Tokens in the Doc object doc and print out their linguistic annotations, the results shows that the information from the CoNLL-U annotations have been carried over to the Doc object.

# Loop over the first 8 Tokens using the range() function
for token_ix in range(0, 8):
    
    # Use the current number under 'token_ix' to fetch a Token from the Doc.
    # Assign the Token object under the variable 'token'. 
    token = doc[token_ix]
    
    # Print the Token and its linguistic annotations
    print(token, token.tag_, token.pos_, token.morph, token.dep_, token.head)
How WRB SCONJ PronType=Int mark Cope
to TO PART  mark Cope
Cope VB VERB VerbForm=Inf ROOT Cope
With IN ADP  case Failure
a DT DET Definite=Ind|PronType=Art det Failure
Double JJ ADJ Degree=Pos amod Failure
Parachute NN NOUN Number=Sing compound Failure
Failure NN NOUN Number=Sing obl Cope

However, if we attempt to retrieve the noun phrases in the Doc objects available under the attribute noun_chunks, spaCy will return an error.

# Get the noun chunks in the Doc
list(doc.noun_chunks)
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
Input In [47], in <cell line: 2>()
      1 # Get the noun chunks in the Doc
----> 2 list(doc.noun_chunks)

File ~/alt/lib/python3.9/site-packages/spacy/tokens/doc.pyx:852, in noun_chunks()

NotImplementedError: [E894] The 'noun_chunks' syntax iterator is not implemented for language ''.

This raises an error, because the Doc that we created using the conllu_to_docs() function does not have a Language and a Vocabulary associated with it.

The noun phrases are created using language-specific rules from syntactic parses, but spaCy does not know which language it is working with.

Because the language of a Doc cannot be defined manually, we must use a trick involving the DocBin object that we learned about in Part II.

The DocBin is a special object type for writing spaCy annotations to disk.

# Import the DocBin object from the 'tokens' submodule
from spacy.tokens import DocBin

# Create an empty DocBin object
doc_bin = DocBin()

# Add the current Doc to the DocBin
doc_bin.add(doc)

Instead of writing the DocBin object to disk, we simply retrieve the Doc objects from the DocBin using the get_docs() method, which requires a Vocabulary object as input to the vocab argument.

The Vocabulary is used to associate the Doc objects with a given language.

The get_docs() method returns a generator, which we must cast into a list.

# Use the 'get_docs' method to retrieve the Docs from the DocBin
docs = list(doc_bin.get_docs(vocab=nlp.vocab))

If we now examine the Doc object, which is naturally the first and only item in the list, and retrieve its attribute noun_chunks, we can also get the noun phrases.

list(docs[0].noun_chunks)[:10]
[it,
 and reserve parachutes,
 this,
 these coping strategies,
 Steps,
 This,
 both your primary and reserve chutes,
 who,
 this,
 you]

This section should have given you a basic understanding of the CoNLL-U annotation schema and how corpora annotated using this schema can be added to spaCy objects.