这里有一种方法：

import ast
import pandas as pd

series = pd.Series([
    "[['word1', 527], ['word2', 708]]",
    "[['word3', 976], ['word1', 980], ['word3', 100]]"
])

out = (
    series
    .apply(ast.literal_eval) # Parse the strings to list[tuple[str, int]]
    .explode()               # Place each tuple on its own line
    .apply(pd.Series)        # Convert to dataframe with 2 columns: word and number
    .groupby(0)[1]           # Group by word, compute on number
    .mean()                  # Take the mean
)

输出：

0
word1    753.5
word2    708.0
word3    538.0
Name: 1, dtype: float64

但我会认真考虑你的数据格式