"It's important to realize that POS tagging is not a fixed property of a word -- but depends on the context of each word. The NLTK book gives an example of [homonyms](http://www.nltk.org/book_1ed/ch05.html#using-a-tagger) -- words that are written the same, but are actually pronounced differently and have different meanings depending on their use."
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"[('They', 'PRP'),\n",
" ('refuse', 'VBP'),\n",
" ('to', 'TO'),\n",
" ('permit', 'VB'),\n",
" ('us', 'PRP'),\n",
" ('to', 'TO'),\n",
" ('obtain', 'VB'),\n",
" ('the', 'DT'),\n",
" ('refuse', 'NN'),\n",
" ('permit', 'NN')]"
]
},
"execution_count": 3,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"text = nltk.word_tokenize(\"They refuse to permit us to obtain the refuse permit\")\n",
"nltk.pos_tag(text)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"From the book:\n",
"\n",
"> Notice that refuse and permit both appear as a present tense verb (VBP) and a noun (NN). E.g. refUSE is a verb meaning \"deny,\" while REFuse is a noun meaning \"trash\" (i.e. they are not homophones). Thus, we need to know which word is being used in order to pronounce the text correctly. (For this reason, text-to-speech systems usually perform POS-tagging.)"
