Question

该程序将采用Binary.text中的语法规则并将其存储到字典中，其中规则为：

N = N D
N = D
D = 0
D = 1

但当前代码返回D：D = 1，N：N = D，而我想要N：N D，N：D，D：0，D：1

import sys
import string

#default length of 3
stringLength = 3

#get last argument of command line(file)
filename1 = sys.argv[-1]


#get a length from user
try:
    stringLength = int(input('Length? '))
    filename = input('Filename: ')
except ValueError:
    print("Not a number")

#checks
print(stringLength)
print(filename)

def str2dict(filename="Binary.txt"):
    result = {}
    with open(filename, "r") as grammar:
        #read file 
        lines = grammar.readlines()
        count = 0
        #loop through
        for line in lines:
            print(line)
            result[line[0]] = line
            print (result)
    return result

print (str2dict("Binary.txt"))

Answer 1

首先，您选择的数据结构错误。 python中的字典是一个简单的键值映射。您喜欢的是从键到多个值的映射。为此，您需要：

from collections import defaultdict
result = defaultdict(list)

接下来，你在哪里分裂＆＃39; =＆＃39; ？您需要这样做才能获得您正在寻找的正确密钥/值？你需要

key, value = line.split('=', 1) #Returns an array, and gets unpacked into 2 variables

将上述两者放在一起，你可以通过以下方式进行：

result = defaultdict(list)
with open(filename, "r") as grammar:
    #read file 
    lines = grammar.readlines()
    count = 0
    #loop through
    for line in lines:
        print(line)
        key, value = line.split('=', 1)
        result[key.strip()].append(value.strip())
return result

Answer 2

根据定义，词典不能有重复的键。因此，只有一个单一的D＆＃39;键。但是，如果您愿意，可以在该键上存储值列表。例如：

from collections import defaultdict

# rest of your code...

result = defaultdict(list) # Use defaultdict so that an insert to an empty key creates a new list automatically
with open(filename, "r") as grammar:
    #read file 
    lines = grammar.readlines()
    count = 0
    #loop through
    for line in lines:
        print(line)
        result[line[0]].append(line)
        print (result)
return result

这将导致类似：

{"D" : ["D = N D", "D = 0", "D = 1"], "N" : ["N = D"]}

字典在Python中覆盖

2 个答案: