如何计数，一列中的值与另一列中的值相同的频率

import csv

def count_frequency(file_path, column_a, column_b):
    frequency = {}
    
    with open(file_path, 'r') as file:
        reader = csv.DictReader(file)
        
        for row in reader:
            value_a = row[column_a]
            value_b = row[column_b]
            
            if value_a == value_b:
                if value_a in frequency:
                    frequency[value_a] += 1
                else:
                    frequency[value_a] = 1
    
    sorted_frequency = sorted(frequency.items(), key=lambda x: x[1], reverse=True)
    
    return sorted_frequency

# 示例调用
file_path = 'data.csv'
column_a = 'A'
column_b = 'B'
result = count_frequency(file_path, column_a, column_b)

for value, freq in result:
    print(f"值为 {value} 的频率为 {freq}")