Python之常用模块（一）

• Z时代
• 2024-01-10
• 分类：综合

time & datatime 模块

random

os

sys

shutil

json & picle

time & datetime

• 时间戳（1970年1月1日之后的秒数，即：time.time()
• 格式化的字符串（如：2016-02-24 14:20 即： time.strftime('%Y-%m-%d')
• 结构化时间（元组包含了：年，日，星期等…time.struct_time 即：time.localtime() ）

time

improt time

print(time.time()) #返回当前系统时间戳(1456298369.1798413)

print(time.ctime()) #输出Tue Jan 26 18:23:48 2016 ,当前系统时间('Wed Feb 24 15:19:51 2016')

print(time.ctime(time.time()-86640)) #将时间戳转为字符串格式('Tue Feb 23 15:16:36 2016')

print(time.gmtime(time.time()-86640)) #将时间戳转换成struct_time格式(

time.struct_time(tm_year=2016, tm_mon=2, tm_mday=23, tm_hour=7, tm_min=17, tc=22, tm_wday=1, tm_yday=54, tm_isdst=0) )

print(time.localtime(time.time()-86640)) #将时间戳转换成struct_time格式,但返回 的本地时间(

time.struct_time(tm_year=2016, tm_mon=2, tm_mday=23, tm_hour=15, tm_min=19, tm_sec=15, tm_wday=1, tm_yday=54, tm_isdst=0) )

print(time.mktime(time.localtime())) #与time.localtime()功能相反,将struct_time格式转回成时间戳格式(1456298734.0)

time.sleep(4) #sleep(暂停)

print(time.strftime("%Y-%m-%d %H:%M:%S",time.gmtime()) )#将struct_time格式转成指定的字符串格式('2016-02-24 07:26:31')

print(time.strptime("2016-01-28","%Y-%m-%d") ) #将字符串格式转换成struct_time格式(

time.struct_time(tm_year=2016, tm_mon=1, tm_mday=28, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=28, tm_isdst=-1) )

datetime

improt datetime

print(datetime.date.today()) #输出格式 2016-01-26

print(datetime.date.fromtimestamp(time.time()-864400) ) #2016-01-16 将时间戳转成日期格式

current_time =datetime.datetime.now() #

print(current_time) #输出2016-01-26 19:04:30.335935

print(current_time.timetuple()) #返回struct_time格式

datetime.replace([year[, month[, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]]]]])

print(current_time.replace(2014,9,12)) #输出2014-09-12 19:06:24.074900,返回当前时间,但指定的值将被替换

str_to_date =datetime.datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M") #将字符串转换成日期格式

new_date =datetime.datetime.now() +datetime.timedelta(days=10) #比现在加10天

new_date =datetime.datetime.now() +datetime.timedelta(days=-10) #比现在减10天

new_date =datetime.datetime.now() +datetime.timedelta(hours=-10) #比现在减10小时

new_date =datetime.datetime.now() +datetime.timedelta(seconds=120) #比现在+120s

print(new_date)

random

随机数

import random

random.random()                 #随机生成一个0到1之间的小数（如：0.3089169738622193，0.241230223660156）

random.randint(1,5)            #随机生成一个1到5的数（包括5）

random.randrange(1,5)     #随机生成一个1到5的数（不包括5）

实例：

生成一个验证码

import random
checkcode = ''
for i in range(4):
    current = random.randint(0,4)
    if current != i:
        temp = chr(random.randint(65,90))
    else:
        temp = random.randint(0,9)
    checkcode += str(temp)
print checkcode

os

提供对操作系统进行调用的接口

os.getcwd() 获取当前工作目录，即当前python脚本工作的目录路径

os.chdir("dirname")  改变当前脚本工作目录；相当于shell下cd

os.curdir  返回当前目录: ('.')

os.pardir  获取当前目录的父目录字符串名：('..')

os.makedirs('dirname1/dirname2')    可生成多层递归目录

os.removedirs('dirname1')    若目录为空，则删除，并递归到上一级目录，如若也为空，则删除，依此类推

os.mkdir('dirname')    生成单级目录；相当于shell中mkdir dirname

os.rmdir('dirname')    删除单级空目录，若目录不为空则无法删除，报错；相当于shell中rmdir dirname

os.listdir('dirname')    列出指定目录下的所有文件和子目录，包括隐藏文件，并以列表方式打印

os.remove()  删除一个文件

os.rename("oldname","newname")  重命名文件/目录

os.stat('path/filename')  获取文件/目录信息

os.sep    输出操作系统特定的路径分隔符，win下为"\\",Linux下为"/"

os.linesep    输出当前平台使用的行终止符，win下为"\t\n",Linux下为"\n"

os.pathsep    输出用于分割文件路径的字符串

os.name    输出字符串指示当前使用平台。win->'nt'; Linux->'posix'

os.system("bash command")  运行shell命令，直接显示

os.environ  获取系统环境变量

os.path.abspath(path)  返回path规范化的绝对路径

os.path.split(path)  将path分割成目录和文件名二元组返回

os.path.dirname(path)  返回path的目录。其实就是os.path.split(path)的第一个元素

os.path.basename(path)  返回path最后的文件名。如何path以／或\结尾，那么就会返回空值。即os.path.split(path)的第二个元素

os.path.exists(path)  如果path存在，返回True；如果path不存在，返回False

os.path.isabs(path) 如果path是绝对路径，返回True

os.path.isfile(path)  如果path是一个存在的文件，返回True。否则返回False

os.path.isdir(path)  如果path是一个存在的目录，则返回True。否则返回False

os.path.join(path1[, path2[, ...]])  将多个路径组合后返回，第一个绝对路径之前的参数将被忽略

os.path.getatime(path)  返回path所指向的文件或者目录的最后存取时间

os.path.getmtime(path)  返回path所指向的文件或者目录的最后修改时间

sys

sys.argv           命令行参数List，第一个元素是程序本身路径，可以跟参数，在执行过程中可以读取到参数

sys.exit(n)        退出程序，正常退出时exit(0)

sys.version        获取Python解释程序的版本信息

sys.maxint         最大的Int值

sys.path           返回模块的搜索路径，初始化时使用PYTHONPATH环境变量的值

sys.platform       返回操作系统平台名称

shutil

高级的文件，文件夹，压缩包 处理模块

shutil.copyfileobj(fsrc, fdst[, length])

将文件内容拷贝到另一个文件中，可以部分内容

def copyfileobj(fsrc, fdst, length=16*1024):
    """copy data from file-like object fsrc to file-like object fdst"""
    while 1:
        buf = fsrc.read(length)
        if not buf:
            break
        fdst.write(buf)

shutil.copyfile(src, dst)

拷贝文件

def copyfile(src, dst):
    """Copy data from src to dst"""
    if _samefile(src, dst):
        raise Error("`%s` and `%s` are the same file" % (src, dst))
    for fn in [src, dst]:
        try:
            st = os.stat(fn)
        except OSError:
            # File most likely does not exist
            pass
        else:
            # XXX What about other special files? (sockets, devices...)
            if stat.S_ISFIFO(st.st_mode):
                raise SpecialFileError("`%s` is a named pipe" % fn)
    with open(src, 'rb') as fsrc:
        with open(dst, 'wb') as fdst:
            copyfileobj(fsrc, fdst)

shutil.copymode(src, dst)

仅拷贝权限。内容、组、用户均不变

def copymode(src, dst):
    """Copy mode bits from src to dst"""
    if hasattr(os, 'chmod'):
        st = os.stat(src)
        mode = stat.S_IMODE(st.st_mode)
        os.chmod(dst, mode)

shutil.copystat(src, dst)

拷贝状态的信息，包括：mode bits, atime, mtime, flags

def copystat(src, dst):

    """Copy all stat info (mode bits, atime, mtime, flags) from src to dst"""

    st = os.stat(src)

    mode = stat.S_IMODE(st.st_mode)

    if hasattr(os, 'utime'):

        os.utime(dst, (st.st_atime, st.st_mtime))

    if hasattr(os, 'chmod'):

        os.chmod(dst, mode)

    if hasattr(os, 'chflags') and hasattr(st, 'st_flags'):

        try:

            os.chflags(dst, st.st_flags)

        except OSError, why:

            for err in 'EOPNOTSUPP', 'ENOTSUP':

                if hasattr(errno, err) and why.errno == getattr(errno, err):

                    break

            else:

                raise

shutil.copy(src, dst)

拷贝文件和权限

def copy(src, dst):

    """Copy data and mode bits ("cp src dst").

    The destination may be a directory.

    """

    if os.path.isdir(dst):

        dst = os.path.join(dst, os.path.basename(src))

    copyfile(src, dst)

    copymode(src, dst)

shutil.copy2(src, dst)

拷贝文件和状态信息

def copy2(src, dst):

    """Copy data and all stat info ("cp -p src dst").

    The destination may be a directory.

    """

    if os.path.isdir(dst):

        dst = os.path.join(dst, os.path.basename(src))

    copyfile(src, dst)

    copystat(src, dst)

shutil.copytree(src, dst, symlinks=False, ignore=None)

递归的去拷贝文件

例如：copytree(source, destination, ignore=ignore_patterns('*.pyc', 'tmp*'))

def ignore_patterns(*patterns):

    """Function that can be used as copytree() ignore parameter.

    Patterns is a sequence of glob-style patterns

    that are used to exclude files"""

    def _ignore_patterns(path, names):

        ignored_names = []

        for pattern in patterns:

            ignored_names.extend(fnmatch.filter(names, pattern))

        return set(ignored_names)

    return _ignore_patterns

def copytree(src, dst, symlinks=False, ignore=None):

    """Recursively copy a directory tree using copy2().

    The destination directory must not already exist.

    If exception(s) occur, an Error is raised with a list of reasons.

    If the optional symlinks flag is true, symbolic links in the

    source tree result in symbolic links in the destination tree; if

    it is false, the contents of the files pointed to by symbolic

    links are copied.

    The optional ignore argument is a callable. If given, it

    is called with the `src` parameter, which is the directory

    being visited by copytree(), and `names` which is the list of

    `src` contents, as returned by os.listdir():

        callable(src, names) -> ignored_names

    Since copytree() is called recursively, the callable will be

    called once for each directory that is copied. It returns a

    list of names relative to the `src` directory that should

    not be copied.

    XXX Consider this example code rather than the ultimate tool.

    """

    names = os.listdir(src)

    if ignore is not None:

        ignored_names = ignore(src, names)

    else:

        ignored_names = set()

    os.makedirs(dst)

    errors = []

    for name in names:

        if name in ignored_names:

            continue

        srcname = os.path.join(src, name)

        dstname = os.path.join(dst, name)

        try:

            if symlinks and os.path.islink(srcname):

                linkto = os.readlink(srcname)

                os.symlink(linkto, dstname)

            elif os.path.isdir(srcname):

                copytree(srcname, dstname, symlinks, ignore)

            else:

                # Will raise a SpecialFileError for unsupported file types

                copy2(srcname, dstname)

        # catch the Error from the recursive copytree so that we can

        # continue with other files

        except Error, err:

            errors.extend(err.args[0])

        except EnvironmentError, why:

            errors.append((srcname, dstname, str(why)))

    try:

        copystat(src, dst)

    except OSError, why:

        if WindowsError is not None and isinstance(why, WindowsError):

            # Copying file access times may fail on Windows

            pass

        else:

            errors.append((src, dst, str(why)))

    if errors:

        raise Error, errors

shutil.rmtree(path[, ignore_errors[, onerror]])

递归的去删除文件

def rmtree(path, ignore_errors=False, onerror=None):

    """Recursively delete a directory tree.

    If ignore_errors is set, errors are ignored; otherwise, if onerror

    is set, it is called to handle the error with arguments (func,

    path, exc_info) where func is os.listdir, os.remove, or os.rmdir;

    path is the argument to that function that caused it to fail; and

    exc_info is a tuple returned by sys.exc_info().  If ignore_errors

    is false and onerror is None, an exception is raised.

    """

    if ignore_errors:

        def onerror(*args):

            pass

    elif onerror is None:

        def onerror(*args):

            raise

    try:

        if os.path.islink(path):

            # symlinks to directories are forbidden, see bug #1669

            raise OSError("Cannot call rmtree on a symbolic link")

    except OSError:

        onerror(os.path.islink, path, sys.exc_info())

        # can't continue even if onerror hook returns

        return

    names = []

    try:

        names = os.listdir(path)

    except os.error, err:

        onerror(os.listdir, path, sys.exc_info())

    for name in names:

        fullname = os.path.join(path, name)

        try:

            mode = os.lstat(fullname).st_mode

        except os.error:

            mode = 0

        if stat.S_ISDIR(mode):

            rmtree(fullname, ignore_errors, onerror)

        else:

            try:

                os.remove(fullname)

            except os.error, err:

                onerror(os.remove, fullname, sys.exc_info())

    try:

        os.rmdir(path)

    except os.error:

        onerror(os.rmdir, path, sys.exc_info())

shutil.move(src, dst)

递归的去移动文件

def move(src, dst):

    """Recursively move a file or directory to another location. This is

    similar to the Unix "mv" command.

    If the destination is a directory or a symlink to a directory, the source

    is moved inside the directory. The destination path must not already

    exist.

    If the destination already exists but is not a directory, it may be

    overwritten depending on os.rename() semantics.

    If the destination is on our current filesystem, then rename() is used.

    Otherwise, src is copied to the destination and then removed.

    A lot more could be done here...  A look at a mv.c shows a lot of

    the issues this implementation glosses over.

    """

    real_dst = dst

    if os.path.isdir(dst):

        if _samefile(src, dst):

            # We might be on a case insensitive filesystem,

            # perform the rename anyway.

            os.rename(src, dst)

            return

        real_dst = os.path.join(dst, _basename(src))

        if os.path.exists(real_dst):

            raise Error, "Destination path '%s' already exists" % real_dst

    try:

        os.rename(src, real_dst)

    except OSError:

        if os.path.isdir(src):

            if _destinsrc(src, dst):

                raise Error, "Cannot move a directory '%s' into itself '%s'." % (src, dst)

            copytree(src, real_dst, symlinks=True)

            rmtree(src)

        else:

            copy2(src, real_dst)

            os.unlink(src)

shutil.make_archive(base_name, format,...)

创建压缩包并返回文件路径，例如 zip , tar

• base_name：压缩包的文件名，也可以是压缩包的路径。文件名时，保存至当前目录
• format：压缩包类型，zip , tar ,bztar , gztar
• root_dir：要压缩的文件夹路径（默认当前目录）
• owner：用户，默认当前用户
• group：组，默认当前组
• logger：用于记录日志，通常是logging.Logger对象

json & pickle 模块

用于序列化的两个模块

json，用于字符串和pyhton数据类型间进行转换，所有语言中都通用

pickle，用于python特有的类型和python的数据类型间进行转换

两个模块都提供了四个功能：dumps , dump , loads , load

dump ：直接将序列化后的字符写到文件中

dumps：是将序列化后的字符先赋给一个变量，然后再用write方法将其写到文件中

load：直接从文件中读取内容

loads：是从内存中读取文件的内容

imort pickle

data = {‘k1’:123,’k2’:’hello’}

p_str = pickle.dumps(data)

with open(‘rueslt.pk’,’w’) as fp:

pickle.dump(data,fp)

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