如何使 json 解析校验码更短或更易读？

Question

Is there a simpler or more idiomatic way to write this?

def jsonToCsvPart1(fields):
    csvFormat = ''
    fields = json.loads(fields)
    for key in fields.keys() :
        tf = str(fields[key])
        mk = ''
        for idx in tf :
            if idx == '{' or idx == '}' or idx == '[' or idx == ']' :
                continue
            else :
               mk += idx
        csvFormat += (mk + ",")
    yield csvFormat

Answer 1

I'm not sure what the grand scheme is, but you can write it in a way that will likely be faster:

Here, assuming you are building a string:

exclude = set(list('{}[]'))  # note: set is faster than list for membership test
mk = ''.join([idx for idx in tf if idx not in exclude])
# 61 ms on a 1M-char random string

exclude = '{}[]'  # ...but string is even faster, when so short
mk = ''.join([idx for idx in tf if idx not in exclude])
# 38 ms on a 1M-char random string

By the way, it will be considerably faster to achieve the same by letting the large loop (on all chars of tf ) be done by builtin functions, and just iterate on the chars to exclude:

mk = tf.replace('{', '').replace('}', '').replace('[', '').replace(']', '')
# 11.8ms on 1M chars

And yet faster:

mk = tf.translate({ord(c): None for c in '{}[]'})
# 4.5 ms on 1M chars

Setup (if anyone is interested to look for yet a faster way):

tf = ''.join(np.random.choice(list('abcdefghijk{}[]'), size=1_000_000))

Answer 2

For your specific purpose (and learning), checking specific chars in a string will work. python set are faster for checking membership. You can refer to others's answers on how to do that. eg.

idxs = '{}[]'
for idx in tf:
    if idx in idxs:
        continue
    else:
        mk += idx

Answer 3

I cannot find more readable names as there is no sample data, so I keep them untouched.

You could probably nest these two for loops together, to get even less lines, but poor readability IMHO.

def jsonToCsvPart1(fields):
    csvFormats = []
    for tf in json.loads(fields):
        mk = ''.join(str(idx) for idx in tf if str(idx) not in '{}[]')
        csvFormats.append(mk)
    yield ','.join(csvFormats)