统计每一系列熊猫DataFrame中的特定单词

import pandas as pd
import re

data = {'Series1': ['This is a sample sentence.', 'Another sentence here.'],
        'Series2': ['Some words in this sentence.', 'More words in another sentence.']}
df = pd.DataFrame(data)

def count_words(series, word):
    count = 0
    for sentence in series:
        words = re.findall(r'\b{}\b'.format(word), sentence)
        count += len(words)
    return count

word = 'sentence'
for column in df.columns:
    count = count_words(df[column], word)
    print("在{}中出现的次数：{}".format(column, count))