After installing Greynir, fire up your Python 3 interpreter:

$ python3

…and try something like the following:

from reynir import NounPhrase as Nl

# Create a NounPhrase ('nafnliður') object
nl = Nl("þrír lúxus-miðar á Star Wars og tveir brimsaltir pokar af poppi")

# Print the NounPhrase in the correct case for each context
# (þf=þolfall/accusative, þgf=þágufall/dative)

print("Þú keyptir {nl:þf}.".format(nl=nl))
print("Hér er kvittunin þín fyrir {nl:þgf}.".format(nl=nl))

The program outputs the following text, correctly inflected:

Þú keyptir þrjá lúxus-miða á Star Wars og tvo brimsalta poka af poppi.
Hér er kvittunin þín fyrir þremur lúxus-miðum á Star Wars og tveimur brimsöltum pokum af poppi.

Use the NounPhrase class to easily inflect Icelandic noun phrases and to convert them between cases, for instance in user interfaces, in chatbot conversations and in printouts.

A more detailed, lower-level example is as follows:

from reynir import Greynir

my_text = "Litla gula hænan fann fræ. Það var hveitifræ."

# Initialize the Greynir parser and submit the text as a parse job
g = Greynir()
job = g.submit(my_text)

# Iterate through sentences and parse each one
for sent in job:
    print("Sentence: {0}".format(sent.tidy_text))
    print("Lemmas:   {0}".format(sent.lemmas))
    print("Parse tree:\n{0}\n".format(sent.tree.view))

The output of the program is:

Sentence: Litla gula hænan fann fræ.
Lemmas:   ['lítill', 'gulur', 'hæna', 'finna', 'fræ', '.']
Parse tree:
      +-lo_nf_et_kvk: 'Litla'
      +-lo_nf_et_kvk: 'gula'
      +-no_et_nf_kvk: 'hænan'
        +-so_1_þf_et_p3: 'fann'
        +-no_et_þf_hk: 'fræ'
Sentence: Það var hveitifræ.
Lemmas:   ['það', 'vera', 'hveitifræ', '.']
Parse tree:
      +-pfn_hk_et_nf: 'Það'
        +-so_1_nf_et_p3: 'var'
        +-no_et_nf_hk: 'hveitifræ'

The code first creates an instance of the Greynir class and assigns it to the g object. The Greynir class is Greynir’s main service interface.

Next, the program submits a piece of text containing two sentences to Greynir, which returns a job object. Each job object encapsulates a stream of sentences that will be, or have been, processed through Greynir’s tokenizer and parser.

A job object is a Python generator, and the for loop iterates through the job’s sentence stream, returning each sentence in turn in the sent object.

The for loop body parses the sentence by calling sent.parse(). This function returns True if the sentence was successfully parsed, i.e. at least one valid parse tree was found for it, or False otherwise.

The sentence object has a number of properties, including sent.tidy_text which returns a normalized form of the tokenized sentence.

If the sentence was successfully parsed, the sent.tree property (of type SimpleTree) contains its best parse tree. This tree can be further queried via properties such as sent.lemmas, which returns a list of the word lemmas in the sentence, and sent.tree.view, which returns a string with an “ASCII art” representation of the parse tree.

The parse tree contains grammar nonterminals in uppercase, such as S0 (root), S-MAIN (main sentence), IP (inflected phrase - beygingarliður), NP-SUBJ (noun phrase - subject, frumlag), VP (verb phrase - sagnliður), etc.

Nonterminals are listed and explained in the Nonterminals section.

The tree also shows grammar terminals (leaves, corresponding to tokens) in lowercase, as well as their grammatical variants (features). Examples are pfn_hk_et_nf (personal pronoun, neutral gender, singular, nominative case), and so_1_nf_et_p3 (verb, one argument in nominative case, singular, 3rd person).

Terminals and variants are listed and explained in the Terminals section.

The sentence and tree properties and functions are further detailed and described in the Reference section.