从字符串列表中提取8位数字

Question

I have a list of strings which may contain letters, symbols, digits, etc, as below:

list = ['\n', '', '0', '38059', '', '', '?_', '71229366', '', '1', '38059', '', '', '?_', '87640804', '', '2', '38059', '', '', '?_', '71758011', '', '', ':?', ';__', '71229366287640804271758011287169822']

How do I filter out all other strings, except numbers less than 10000000 and greater than 99999999?

Expected Output:

list = ['71229366', '87640804', '71758011']

Answer 1

如果您不介意制作新列表，则可以尝试使用列表理解功能，例如

filtered_list = [i for i in list if i.isdigit() and 10000000 < int(i) < 99999999]

Answer 2

You can use a map and filter .

your_list = ['\n', '', '0', '38059', '', '', '?_', '71229366', '', '1', '38059', 
             '', '', '?_', '87640804', '', '2', '38059', '', '', '?_', '71758011', 
             '', '', ':?', ';__', '71229366287640804271758011287169822']

new_list = list(map(int, filter(lambda x: x.isdigit() and 10000000 < int(x) < 99999999, your_list)))
print(new_list)

list() optional on python2.

Output:

[71229366, 87640804, 71758011]

---

If you don't want the conversion to integer, drop the map :

>>> list(filter(lambda x: x.isdigit() and 10000000 < int(x) < 99999999, your_list))
['71229366', '87640804', '71758011']

Answer 3

def valid(v):
    try:
        value = int(v)
        return 10000000 <= value <= 99999999
    except:
        return False

output = [x for x in list if valid(x)]

Explanation :

Filter all values in the list using the valid function as your criteria.

Answer 4

data = ['\n', '', '0', '38059', '', '', '?_', '71229366', '', '1', '38059', 
        '', '', '?_', '87640804', '', '2', '38059', '', '', '?_', '71758011', 
        '', '', ':?', ';__', '71229366287640804271758011287169822']

res = []
for e in data:
    try:
        number = int(e)
    except ValueError:
        continue
    if 10000000  < number < 99999999:
        res.append(str(number))

print(res)

print(res)

Output:

 ['71229366', '87640804', '71758011']

Answer 5

Let me provide a simple and efficient answer, using regular expressions. There's no need to map (duplicating the original list), or to convert everything to int s; you are basically asking how to keep all 8-digit integers in your list:

>>> filter(re.compile('^\d{8}$').match, data)
['71229366', '87640804', '71758011']

We compile a regular expression which matches exactly 8 digits and then filter the list by providing a partial application of regex.match to the standard filter function.