How to Extract Exact 6‑Digit Codes from Mixed Text Using Python Regex

1. Introduction

The author shares a question from a Python community about extracting a continuous six‑digit number from a column that mixes letters, digits, and case‑sensitive characters, while ignoring sequences longer or shorter than six digits.

2. Implementation

Several contributors propose solutions. The first approach lists all possible patterns per row and merges the results. An illustrative diagram is shown below.

A more concrete code snippet is provided:

def extract_digits(my_list):
    target_digits = []
    for item in my_list:
        for i in range(len(item)):
            if item[i:i+6].isdigit() and len(item[i:i+6]) == 6:
                target_digits.append(item[i:i+6])
    return target_digits

my_list = ['abc123', '123456', 'xyz789', '9876543', '12qw345', '12345678']
target_digits = extract_digits(my_list)
print(target_digits)

The snippet works but still needs refinement.

Another contributor suggests using regular expressions with pandas for CSV data:

df = pd.read_csv('示例.csv', encoding='gbk')
pattern = r'\D(\d{6})(?=\D|$)'
df['提取单号'] = df['理由'].map(lambda x: re.findall(pattern, x)[0] if len(re.findall(pattern, x)) >= 1 else 0)
print(df)

The expected output is displayed in the following image.

Although the solution works, a small issue remains for future discussion.

3. Conclusion

The article summarizes the Python regex data‑extraction problem, presents multiple community‑derived solutions with code, and helps readers apply these techniques to their own datasets.