Prevent Spacy tokenizer from splitting on specific character

Question

When using spacy to tokenize a sentence, I want it to not split into tokens on /

Example:

import en_core_web_lg
nlp = en_core_web_lg.load()
for i in nlp("Get 10ct/liter off when using our App"):
    print(i)

Output:

Get
10ct
/
liter
off
when
using
our
App

I want it to be like Get , 10ct/liter, off, when ....

I was able to find how to add more ways to split into tokens for spacy, but not how to avoid specific splitting techniques.

Answer 1

I suggest using a custom tokenizer, see Modifying existing rule sets:

import spacy
from spacy.lang.char_classes import ALPHA, ALPHA_LOWER, ALPHA_UPPER, HYPHENS
from spacy.lang.char_classes import CONCAT_QUOTES, LIST_ELLIPSES, LIST_ICONS
from spacy.util import compile_infix_regex

nlp = spacy.load("en_core_web_trf")
text = "Get 10ct/liter off when using our App"
# Modify tokenizer infix patterns
infixes = (
    LIST_ELLIPSES
    + LIST_ICONS
    + [
        r"(?<=[0-9])[+\-\*^](?=[0-9-])",
        r"(?<=[{al}{q}])\.(?=[{au}{q}])".format(
            al=ALPHA_LOWER, au=ALPHA_UPPER, q=CONCAT_QUOTES
        ),
        r"(?<=[{a}]),(?=[{a}])".format(a=ALPHA),
        r"(?<=[{a}])(?:{h})(?=[{a}])".format(a=ALPHA, h=HYPHENS),
        #r"(?<=[{a}0-9])[:<>=/](?=[{a}])".format(a=ALPHA),
        r"(?<=[{a}0-9])[:<>=](?=[{a}])".format(a=ALPHA),
    ]
)

infix_re = compile_infix_regex(infixes)
nlp.tokenizer.infix_finditer = infix_re.finditer
doc = nlp(text)
print([t.text for t in doc])
## =>  ['Get', '10ct/liter', 'off', 'when', 'using', 'our', 'App']

Note the commented #r"(?<=[{a}0-9])[:<>=/](?=[{a}])".format(a=ALPHA), line, I simply took out the / char from the [:<>=/] character class. This rule split at / that is between a letter/digit and a letter.

If you need to still split '12/ct' into three tokens, you will need to add another line below the r"(?<=[{a}0-9])[:<>=](?=[{a}])".format(a=ALPHA) line:

r"(?<=[0-9])/(?=[{a}])".format(a=ALPHA),