python有多少种模块_python如何查看有哪些模块

Question:

如何查看正则表达式模块re及其相关函数的意义

1、终端命令行下

python

>> import sys

>> sys.modules

###################################

一长串信息中字段modules对应的模块即为包含的模块。

###################################

>> import re

>> help(re)

Help on module re:

NAME

re - Support for regular expressions (RE).

FILE

/usr/lib64/python2.7/re.py

DESCRIPTION

This module provides regular expression matching operations similar to

those found in Perl. It supports both 8-bit and Unicode strings; both

the pattern and the strings being processed can contain null bytes and

characters outside the US ASCII range.

Regular expressions can contain both special and ordinary characters.

Most ordinary characters, like "A", "a", or "0", are the simplest

regular expressions; they simply match themselves. You can

concatenate ordinary characters, so last matches the string 'last'.

The special characters are:

"." Matches any character except a newline.

"^" Matches the start of the string.

"$" Matches the end of the string or just before the newline at

the end of the string.

"*" Matches 0 or more (greedy) repetitions of the preceding RE.

Greedy means that it will match as many repetitions as possible.

"+" Matches 1 or more (greedy) repetitions of the preceding RE.

"?" Matches 0 or 1 (greedy) of the preceding RE.

*?,+?,?? Non-greedy versions of the previous three special characters.

{m,n} Matches from m to n repetitions of the preceding RE.

{m,n}? Non-greedy version of the above.

"\\" Either escapes special characters or signals a special sequence.

[] Indicates a set of characters.

A "^" as the first character indicates a complementing set.

"|" A|B, creates an RE that will match either A or B.

(...) Matches the RE inside the parentheses.

The contents can be retrieved or matched later in the string.

(?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see below).

(?:...) Non-grouping version of regular parentheses.

(?P...) The substring matched by the group is accessible by name.

(?P=name) Matches the text matched earlier by the group named name.

(?#...) A comment; ignored.

(?=...) Matches if ... matches next, but doesn't consume the string.

(?!...) Matches if ... doesn't match next.

(?<=...) Matches if preceded by ... (must be fixed length).

(?(id/name)yes|no) Matches yes pattern if the group with id/name matched,

the (optional) no pattern otherwise.

>>> help(re.compile)

Help on function compile in module re:

compile(pattern, flags=0)

Compile a regular expression pattern, returning a pattern object.

(END)

2、IDE环境下(待续……)

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