使用 Python 通过随时间向其写入键/值对来在 txt 文件中构建字典

Question

How can I "build" a dictionary within a txt file using Python, over time?

I need to take two variables, for example...

some_string = "Hello, World!"

some_float = 3958.8

...then write those two variables to a txt file, as a dictionary.

For the key/value pair, some_string should be the key, and some_float should be the value.

Next time I run the program, some_string and some_float may be different, and will need to get written/added to the same txt file, essentially adding another key/value pair to the now already existing dictionary (txt file). If the new key (some_string) is not different, then compare the new value (some_float) with the old value already in the txt file, and if the new value is lesser, then update it in the txt file.

All I've been able to find is information regarding adding a known dictionary to a txt file, not building one up over time. In my case, I don't know ahead of time what some_string and some_float will be next time I run the program, so I can't pre-build the dictionary and just write it all to the txt file at once.

Any ideas?

Answer 1

You can use open file mode append ('a') to append to the file the new content and update the file that way every time you add a new value. Here's an exemple on how to do it:

def add_dic(key, value):
    with open('dic.txt', mode='a') as fp:
        fp.write(key + " " + str(value) + '\n')


def read_dic():
    dic = {}
    with open('dic.txt', mode='r') as fp:
        for line in fp.readlines():
            words = line.split(' ')
            key = words[0]
            value = float(words[1])
            dic[key] = value

    return dic


some_string = input("string: ")
some_float = float(input("float: "))

add_dic(some_string, some_float)

dic = read_dic()
print(dic)