如何统计python中字符之间的转换频率？

def count_character_transitions(string):
    transitions = {}
    for i in range(len(string)-1):
        current = string[i]
        next_char = string[i+1]
        key = current + next_char
        if key in transitions:
            transitions[key] += 1
        else:
            transitions[key] = 1
    return transitions

# 示例用法
text = "hello world"
transitions = count_character_transitions(text)
sorted_transitions = sorted(transitions.items(), key=lambda x: x[1], reverse=True)

for transition, frequency in sorted_transitions:
    print(f"Transition: {transition}, Frequency: {frequency}")