在dataframe中查找列中出现频率最低的字符

import pandas as pd
from collections import Counter

df = pd.read_csv("data.csv")  # 假设数据存储在data.csv文件中

column_data = df["column_name"]

counter = Counter("".join(column_data))

min_freq = min(counter.values())
min_chars = [char for char, freq in counter.items() if freq == min_freq]

print("频率最低的字符是：", min_chars)