如何为列表中的每个项目应用内容

Question

def get_key(file):
    '''(file open for reading) -> tuple of objects

       Return a tuple containing an int of the group length and a dictionary of
       mapping pairs.
    '''

    f = open(file, 'r')
    dic = f.read().strip().split()
    group_length = dic[0]
    dic[0] = 'grouplen' + group_length
    tup = {}
    tup['grouplen'] = group_length
    idx = 1
    dic2 = dic
    del dic2[0]
    print(dic2)

    for item in dic2:
        tup[item[0]] = item[1]
        print(tup)


        return tup

The result is: {'grouplen': '2', '"': 'w'} The dic 2 is:

['"w', '#a', '$(', '%}', '&+', "'m", '(F', ')_', '*U', '+J', ',b', '-v', '.<', '/R', '0=', '1$', '2p', '3r', '45', '5~', '6y', '7?', '8G', '9/', ':;', ';x', '<W', '=1', '>z', '?"', '@[', 'A3', 'B0', 'CX', 'DE', 'E)', 'FI', 'Gh', 'HA', 'IN', 'JS', 'KZ', 'L\\', 'MP', 'NC', 'OK', 'Pq', 'Qn', 'R2', 'Sd', 'T|', 'U9', 'V-', 'WB', 'XO', 'Yg', 'Z@', '[>', '\\V', ']%', '^`', '_T', '`,', 'aD', 'b#', 'c:', 'dM', 'e^', 'fu', 'ge', 'hQ', 'i7', 'jY', 'kc', 'l*', 'mH', 'nk', 'o4', 'p8', 'ql', 'rf', 's{', 'tt', 'uo', 'v.', 'w6', 'xL', 'y]', 'zi', '{s', '|j', '}&', "~'"]

I want the tuple to contain all the pairs in dic2 , not just the first two

Answer 1

You need to de-indent the return statement. You are returning in the loop, so in the first iteration.

Instead of:

for item in dic2:
    tup[item[0]] = item[1]
    print(tup)

    return tup

do:

for item in dic2:
    tup[item[0]] = item[1]
    print(tup)

return tup

Now you let the loop do it's work properly and not end the function early.

There probably is a better way to read your file, depending on the format of the file. If each entry is listed on a new line, I'd read it as follows:

def get_key(file):
    '''(file open for reading) -> tuple of objects

       Return a tuple containing an int of the group length and a dictionary of
       mapping pairs.
    '''

    with open(file, 'r') as f:
        grouplen = next(f)  # first line
        res = {'grouplen': int(grouplen)}

        for line in f:
            res[line[0]] = line[1]

    return res

Answer 2

in python, indendation is the key.

for item in dic2:
    ...
    return tup

this makes the return statement fall inside the for loop since the return is indented after the for indentation.

for item in dic2:
    ...
return tup

here, since the for and the return statement are at the same level of indentation, the return statement is executed only after the loop ends, thus returning the whole tuple