Detailed description of several methods of strings in python-Python Tutorial-php.cn

Detailed description of several methods of strings in python

高洛峰

Release： 2017-03-08 11:35:05

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字符串格式化

>>> '%s plus %s equals %s' % (1,1,2)
'1 plus 1 equals 2'

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字段的宽度和精度

*字段宽度是转换后的值所保留的最小字符个数，精度（对于数字）是包含的小数位数，或者（对于字符）转换后的值所能包含的最大字符数

>>> from math import pi
>>> '%10f' % pi
'  3.141593'
>>> from math import pi
>>> '%10f' % pi  #字段宽10
'  3.141593'
>>> '%10.2f' % pi #字段宽10，精度2
'      3.14'
>>> '%.2f' % pi #精度2
'3.14'
>>> '%.5s' % 'My name is ningsi'
'My na'
>>> '%.*s' % (5,'My name is ningsi')
'My na'

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符号、对齐和0填充

>>> '%010.2f' % pi #用0填充
'0000003.14'    
>>> '%-10.2f' % pi #左对齐
'3.14      '
>>> print ('% 5d' % 10)+'\n'+('%5d' % -10)
   10
  -10
>>> print ('%+5d' % 10)+'\n'+('%+5d' % -10)
  +10
  -10

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字符串的方法

find 查找子字符串

>>> N='ning si de shu de'>>> N.find('de')8
>>> N.find('dee')-1
>>> N.find('de',9,16) #范围包含第一个索引不包含第二个-1

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join 是split方法的逆方法

>>> s=['1','2','3','4']
>>> q.join(s)
'1+2+3+4'
>>> p='','usr','bin','env'
>>> '/'.join(p)
'/usr/bin/env'>>> print 'C:'+'\\'.join(p)
C:\usr\bin\env

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lower 返回字符串的小写字母版

>>> &#39;My name is ningsideshu&#39;.lower()
&#39;my name is ningsideshu&#39;
>>> if &#39;name&#39; in [&#39;my&#39;,&#39;Name&#39;,&#39;is&#39;]:print &#39;Found it!&#39;

>>> if &#39;my&#39; in [&#39;my&#39;,&#39;Name&#39;,&#39;is&#39;]:print &#39;Found it!&#39;

Found it!

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replace 替换

>>> &#39;This is a pen&#39;.replace(&#39;pen&#39;,&#39;apple&#39;)&#39;This is a apple&#39;

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split 将字符串分割成序列

>>> &#39;1+2+3+4+5&#39;.split(&#39;+&#39;)
[&#39;1&#39;, &#39;2&#39;, &#39;3&#39;, &#39;4&#39;, &#39;5&#39;]
>>> &#39;/usr/bin/env&#39;.split(&#39;/&#39;)
[&#39;&#39;, &#39;usr&#39;, &#39;bin&#39;, &#39;env&#39;]
>>> &#39;Using the default&#39;.split() #默认所有空格作为分隔符（空格、换行等）
[&#39;Using&#39;, &#39;the&#39;, &#39;default&#39;]

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strip 返回去除两侧空格（或指定字符）的字符串 (另外：lstrip,rstrip)

>>> &#39; My name is Nsds  &#39;.strip()&#39;My name is Nsds&#39;>>> &#39; *My name is Nsds * &#39;.strip(&#39; *&#39;)&#39;My name is Nsds&#39;

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translate 替换，与replace不同的是，可以替换单个字符（字符串中的某些部分）

>>> from string import maketrans
>>> N=maketrans(&#39;ns&#39;,&#39;mf&#39;)
>>> &#39;My name is ningsideshu&#39;.translate(N)
&#39;My mame if mimgfidefhu&#39;
>>> &#39;My name is ningsideshu&#39;.translate(N,&#39;M&#39;) #第二个参数指定需要删除的字符
&#39;y mame if mimgfidefhu&#39;

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模版字符串

>>> from string import Template
>>> s=Template(&#39;$x. name $x!&#39;)
>>> s.substitute(x=&#39;hello&#39;)
&#39;hello. name hello!&#39;
>>> s=Template("It&#39;t ${x}tastic!")
>>> s.substitute(x=&#39;slurm&#39;)
"It&#39;t slurmtastic!"
>>> s=Template("It&#39;t ${x}tastic${y}!")
>>> s.substitute(x=&#39;slurm&#39;,y=&#39;a&#39;)
"It&#39;t slurmtastica!"
>>> s=Template(&#39;A $thing must never $action.&#39;) 
>>> d={}
>>> d[&#39;thing&#39;]=&#39;gentleman&#39;
>>> d[&#39;action&#39;]=&#39;show his socks&#39;
>>> s.substitute(d)
&#39;A gentleman must never show his socks.&#39;

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