Finding all occurrences of 7 consecutive numbers starting and ending with space

Question

I need to find all occurrences of 7 consecutive numbers starting and ending with space in python with regex. If the string starts with set of 7 numbers the space before set must be omitted. If the string ends with set of 7 numbers the space after set must be omitted.

str = "1234567 7777777 88888888  9999999   -7654321 555-5555 456456 123.1245  6666666"

Expected output:

["1234567", "7777777", "9999999", "6666666"]

eg

lst = re.findall("\d{7}", str)

Answer 1

Just find all on (?<?\S)\d{7}(?!\S) :

str = "1234567 7777777 88888888  9999999   -7654321 555-5555 456456 123.1245  6666666"
nums = re.findall(r'(?<!\S)\d{7}(?!\S)', str)
print(nums)  # ['1234567', '7777777', '9999999', '6666666']

The regex pattern used here says to:

(?<!\S)  assert that whitespace or start of string precedes
\d{7}    match a 7 digit number
(?!\S)   assert that whitespace or the end of the string follows