Define labels and data
Decide a POS tagset (e.g. universal POS) and collect domain-matched annotated sentences with token-level labels.
Tag tokens with parts of speech. Assess tagging accuracy.
Part-of-speech (POS) tagging assigns a grammatical category to each token in text. A reliable tagger needs consistent tokenisation, a labelled training set that matches target text, and evaluation that highlights frequent confusion pairs (e.g. noun/verb). Error cases include unknown words, punctuation handling and domain shifts.
Learning concept · Not a validated service
Part-of-speech (POS) tagging assigns a grammatical category to each token in text. A reliable tagger needs consistent tokenisation, a labelled training set that matches target text, and evaluation that highlights frequent confusion pairs (e.g. noun/verb). Error cases include unknown words, punctuation handling and domain shifts.
A proposed application: add POS tagging to a grammar-annotation tool for language learners so they can inspect sentence structure. This extension is not implemented by the supplied starter code.
Decide a POS tagset (e.g. universal POS) and collect domain-matched annotated sentences with token-level labels.
Tokenise consistently and align labels to tokens; handle punctuation, contractions and subword issues before feature extraction.
Train a sequence tagger (CRF or a neural sequence model) and report token-level accuracy and macro F1 per POS class.
Inspect common confusions, add a human-review step for low-confidence tags and monitor domain drift after deployment.
The supplied starter synthesises two groups of sinusoidal signals, extracts simple frequency-spectrum statistics, trains a RandomForest to distinguish the two synthetic classes, and prints a classification report. It contains no text tokenisation, no token-level POS labels and no POS-tagging model.
rows = [synth_clip(440 + rng.normal(0, 20), 0) for _ in range(80)]
rows += [synth_clip(880 + rng.normal(0, 20), 1) for _ in range(80)]
X = np.array([row[0] for row in rows])
y = np.array([row[1] for row in rows])
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.25, random_state=42, stratify=y)
model = RandomForestClassifier(n_estimators=200, random_state=42)
model.fit(X_train, y_train)The code uses synthetic audio-like signals and a binary classifier; it contains no text data, no token-level labels and no sequence or token-tagging logic required for POS tagging.
Proposed extension: replace the synthetic data with an annotated corpus (Universal Dependencies, OntoNotes or a domain-specific dataset), add tokenisation and a sequence tagger (CRF or BiLSTM-CRF), and build a small interface that highlights low-confidence tokens for human review.
This is a potential application pathway, not a delivered product. The supplied starter does not implement this service or validate it with real users.
Networkers Home runs this topic inside its AI Engineer Course, with placement support and hands-on labs.