Python Basics Os.path.join and Split () functions

Python has join and Os.path.join () two functions, which work as follows:

Join: An array of connection strings. Generates a new string from a string, tuple, or element in the list, with the specified character (delimiter) connection
Os.path.join (): Combine multiple paths to return

First, function description

1.join () function

Syntax: ' Sep '. Join (SEQ)

Parameter description:

Sep: Delimiter. Can be empty

SEQ: sequence of elements to concatenate, strings, tuples, dictionaries, etc.

The syntax above is to combine all the SEQ elements into a new string with Sep as a delimiter

Return value: Returns a string that is generated after each element is concatenated with the delimiter Sep

2. Os.path.join () function

Syntax: Os.path.join (path1[,path2[,......])

Return value: Combine multiple paths to return

Note: Parameters before the first absolute path are ignored

Instance:

#对序列进行操作 (use ' and ': ' as separators) >>> seq1 = [' Hello ', ' good ', ' boy ', ' Doiido ']>>> print '. Join (SEQ1) Hello Good boy doiido>>> print ': '. Join (seq1) Hello:good:boy:doiido #对字符串进行操作 >>> seq2 = "Hello good boy doiid O ' >>> print ': '. Join (SEQ2) H:e:l:l:o:: g:o:o:d:: b:o:y::d: o:i:i:d:o #对元组进行操作 >>> seq3 = (' Hello ', ' good ', ' Boy ', ' Doiido ') >>> print ': '. Join (SEQ3) Hello:good:boy:doiido #对字典进行操作 >>> seq4 = {' Hello ': 1, ' good ': 2, ' Boy ': 3, ' Doiido ':4}>>> print ': '. Join (seq4) Boy:good:doiido:hello #合并目录 >>> Import os>> > Os.path.join ('/hello/', ' good/boy/', ' doiido ') '/hello/good/boy/doiido '

There is also a code for the 99 multiplication table on Oschina, as follows (source link: http://www.oschina.net/code/snippet_53549_2238)

print   \ n ' .join ([ .join ([ '%s*%s=%-2s '  %   (y,x,x * y)   for   y   in   range ( 1 ,x + 1 for   < Code class= "Plain" >x  in  range ( 1 10 Code class= "Plain")])

短短一句话，就完美打印出99 multiplication table.

The appreciation of this Code, Baidu blog has an article about the very clear, not much to say in this.

The original text is as follows: (Link: http://hi.baidu.com/fc_lamp/blog/item/fb7d410bf7314c0295ca6b8c.html)

An analysis of a Python code born 99 multiplication table 2011-11-24 11:58

The code for the section 99 multiplication table is recently seen on Oschina, as follows:

print ' \ n '. Join (['%s*%s=%-2s '% (y,x,x*y) fory in range (1,x+1)]) Forx in range (1,10)])

(As for: http://www.oschina.net/code/snippet_53549_2238)

I tweaked a little bit:

#coding: Utf-8
Print (' \ n '. Join ('%sx%s=%-2s '% (x,y,x*y) for x in Xrange (1,y+1)) "For Y in Xrange (1,10)]))

Well, in fact, the two code are not much, then we will parse, this code:

First: The main points of knowledge to be used:

1 List parsing knowledge (and meta-group knowledge)

2 Use of Range,xrange,join functions

3 String formatted output

There are two functions for split () and Os.path.split () in Python:

Split (): Splits the string. Slices a string by specifying a delimiter and returns a list of the split strings.

Os.path.split (): Splits the file name and path.

1. Split () function
Syntax: Str.split (str= "", Num=string.count (str)) [n]

Parameter description:
STR: Represented as a delimiter, the default is a space, but not an empty string. If there is no delimiter in the string, the entire string is used as an element of the list.
Num: Indicates the number of splits. If there is a parameter num, it is separated into only num+1 substrings.
[n]: Indicates the selection of nth shards (counted from 0)

By default, spaces are used as separators, and when separated, empty strings are automatically ignored, such as:

>>> s= ' love    python ' >>> s.split () [' Love ', ' python ']

However, if you explicitly specify a space as a delimiter, an empty string is not automatically ignored, such as:

>>> s.split (') [' Love ', ' ', ' ', ' ', ' python ']

The default delimiter, in addition to spaces, and ' \n\t\r ', is separated and the empty string is automatically ignored, as follows:

>>> s= ' Love \n\t\r  \t\r\n python  \n\t\r ' >>> s.split () [' Love ', ' python '] >>> s= ' Www.pku.edu.cn '

>>> s.split () #默认空格作为分隔符, but there is no delimiter in the string, so the entire string is used as an element of the list
[' www.pku.edu.cn ']

>>> s.split ('. ') #以 '. ' As a delimiter, without specifying the number of separators, the number of '. ' is separated by how many times
[' www ', ' pku ', ' edu ', ' CN ']

>>> s.split ('. ', 0) #分隔0次
[' www.pku.edu.cn ']

>>> s.split ('. ', 1) #分隔1次
[' www ', ' pku.edu.cn ']

>>> s.split ('. ', 2) #分隔2次
[' www ', ' pku ', ' edu.cn ']

>>> s.split ('. ', 2) [1] #分隔2次, take an index of 1
' PKU '

>>> s.split ('. ', -1) #尽可能多的分隔, same as no num parameter
[' www ', ' pku ', ' edu ', ' CN ']

>>> s1,s2=s.split ('. ', 1) #分隔1次, and store the separated 2 strings in S1 and S2
>>> S1
' www

' Love\nhello\npython '
>>> s.split (' \ n ') #以 ' \ n ' as a delimiter with as many separators as possible
[' Love ', ' hello ', ' python ']
>>> Print S
Love
Hello
Python

Practice the following example:

>>> s= ' Hello Python<[www.python.com]>hello python ' >>> s.split (' [') [1].split ('] ') [0] ' Www.python.com ' >>> s.split (' [') [1].split ('] ') [0].split ('. ') [' www ', ' python ', ' com ']

2. Os.path.split () function
Syntax: Os.path.split (' path ')

Parameter description:

1. Path refers to the full path of a file as a parameter:
2. If a directory and filename are given, the output path and file name
3. If a directory name is given, the output path and the empty file name

In fact, the segmentation of the function is not intelligent, it is only the "path" in the last '/' as a delimiter, separated by the index of 0 as a directory (path), the index of 1 as a file name, such as:

>>> Import os>>> os.path.split (' c:/soft/python/test.py ') (' C:/soft/python ', ' test.py ') >> > Os.path.split (' c:/soft/python/test ') (' C:/soft/python ', ' Test ') >>> os.path.split (' c:/soft/python/') ( ' C:/soft/python ', ')

Python basic knowledge os.path.join and Split () function