TextRank extract keywords

textrank_keywords.py

"""
Reference:

http://www.hankcs.com/nlp/textrank-algorithm-to-extract-the-keywords-java-implementation.html

http://www.hankcs.com/nlp/textrank-algorithm-java-implementation-of-automatic-abstract.html
"""

import numpy as np


def similar(word_a, word_b):
    return 1


def new_ws(i, word_i, ws, word_near, d=0.85):
    s = 0
    for j, word_j in enumerate(word_near[word_i]):
        if word_j == word_i:
            continue
        w_j_i = similar(word_j, word_i)
        w_sum_j_k = 0
        for word_k in word_near[word_j]:
            if word_k == word_j:
                continue
            w_sum_j_k += similar(word_j, word_k)
        s += w_j_i / w_sum_j_k * ws[j]
    s = (1 - d) + d * s
    return s


words = [
    '程序员',
    '英文',
    '程序',
    '开发',
    '维护',
    '专业',
    '人员',
    '程序员',
    '分为',
    '程序',
    '设计',
    '人员',
    '程序',
    '编码',
    '人员',
    '界限',
    '特别',
    '中国',
    '软件',
    '人员',
    '分为',
    '程序员',
    '高级',
    '程序员',
    '系统',
    '分析员',
    '项目',
    '经理'
]

word_near = {}

for i, word in enumerate(words):
    if word not in word_near:
        word_near[word] = set()
    start_ind = max(i - 5, 0)
    end_ind = min(i + 5, len(words))
    for j in range(start_ind, end_ind):
        if words[j] != word:
            word_near[word].add(words[j])

words = sorted(list(word_near.keys()))
weight = np.ones(len(words))
max_iter = 200
tol = 1e-3
for i in range(max_iter):
    new_weight = np.array([
        new_ws(i, word_i, weight, word_near)
        for i, word_i in enumerate(words)
    ])
    if np.sum((weight - new_weight) ** 2) < tol:
        break
    weight = new_weight

print(sorted(list(zip(words, weight)), key=lambda x: x[1], reverse=True))