Python练习(四)——字典的应用

1.给出一个字符串，在程序中赋初值为一个句子，例如“To improve is to change;to be perfect is to change often.”

需要：计算句子中各字符出现的频数（通过字典存储）

sentence = input("Please input a sentence:")
sentence_list = list(sentence)
sentence_1 = []
#列表字符去重后
for str_i in sentence:
    if str_i not in sentence_1:
        sentence_1.append(str_i)
chars = {}
for str_i in sentence_1:
    chars[str_i] = sentence_list.count(str_i)
print(chars)