Function step_4

pattern/vector/stemmer.py:219–231

Step 4 strips -ant, -ent etc. suffixes. This only happens if there is more than one vowel-consonant pair before the suffix.

(w)

    (("m","i","s"), ("ism", "iti", "ous"))
]    
def step_4(w):
    """ Step 4 strips -ant, -ent etc. suffixes.
        This only happens if there is more than one vowel-consonant pair before the suffix.
    """
    for suffix, rules in suffixes4:
        if w.endswith(suffix):
            for A in rules:
                if w.endswith(A):
                    return R2(w).endswith(A) and w[:-len(A)] or w
    if R2(w).endswith("ion") and w[:-3].endswith(("s", "t")):
        # Delete -ion if preceded by s or t.
        return w[:-3]
    return w
    
def step_5a(w):
    """ Step 5a strips suffix -e if preceded by multiple vowel-consonant pairs,