import difflib

def similarity(s1, s2):
    if not s1 or not s2: return 0.0
    return difflib.SequenceMatcher(None, s1, s2).ratio()

s1 = "技有限公司"
s2 = "威凯检测技术有限公司"

print(f"s1: '{s1}' (len={len(s1)})")
print(f"s2: '{s2}' (len={len(s2)})")
print(f"Ratio: {similarity(s1, s2):.4f}")

s3 = "检测技术有限"
print(f"\ns3: '{s3}' (len={len(s3)})")
print(f"Ratio s3 vs s2: {similarity(s3, s2):.4f}")