python常用点小记

记录一下，经常用到的一些python小工具

1.验证一个字符串是否为url

regex = re.compile(
        r'^(?:http|ftp)s?://' # http:// or https://
        r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|' #domain...
        r'localhost|' #localhost...
        r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})' # ...or ip
        r'(?::\d+)?' # optional port
        r'(?:/?|[/?]\S+)$', re.IGNORECASE)

2.地址是否为有效的email地址

email_re = re.compile(
    r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"  # dot-atom
    # quoted-string, see also http://tools.ietf.org/html/rfc2822#section-3.2.5
    r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-\011\013\014\016-\177])*"'
    r')@(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$', re.IGNORECASE)

3.检测目录下的文件是否发生变化

_mtimes = {}
_win = (sys.platform == "win32")

def code_changed():
    global _mtimes, _win
    for filename in filter(lambda v: v, map(lambda m: getattr(m, "__file__", None), sys.modules.values())):
        if filename.endswith(".pyc") or filename.endswith(".pyo"):
            filename = filename[:-1]
        if not os.path.exists(filename):
            continue # File might be in an egg, so it can't be reloaded.
        stat = os.stat(filename)
        mtime = stat.st_mtime
        if _win:
            mtime -= stat.st_ctime
        if filename not in _mtimes:
            _mtimes[filename] = mtime
            continue
        if mtime != _mtimes[filename]:
            _mtimes = {}
            return True
    return False

4.python切分队列

if __name__ == '__main__':
    a=[1,2,3,4,5]
    print [a[i:i+4] for i in range(0,len(a),4)]

待续.....