Chars to String的数组 [英] Array of Chars to String

问题描述

您好，


我正在寻找一种很好的方法，只从字符串中获取那些字符串

在另一个字符串中并创建一个新字符串：

astr =" Bob Carol Ted Alice"
letters =" adB"
some_func（astr，letters）

" Bad"


我可以写这样的：


astr =" Bob Carol Ted Alice"

letters =" adB"


导入集

alist = [lttr for lttr in astr if lttr in set（letters）]

newstr =""

for lttr in alist ：

newstr + = lttr


但这看起来很难看。我特别不喜欢newstr + = lttr因为它每次都会使新的字符串变为
。我认为像这样的东西必须已经在某个地方使用

功能，或者我可以使用

内置工具提高效率。


有什么想法吗？


James


-

James Stroud
加州大学洛杉矶分校基因组学和蛋白质组学研究所

专栏951570

洛杉矶，加利福尼亚州90095

http://www.jamesstroud.com/

解决方案

James Stroud< js ***** @ mbi.ucla.edu>写道：

但这看起来很难看。我特别不喜欢newstr + = lttr因为它每次都会成为一个新的字符串。我认为像这样的东西必须已经在某个地方使用
功能，或者我可以使用
内置工具提高效率。

"" .join


''as

James Stroud写道：

您好，

我正在寻找一种很好的方法，只能从字符串中取出那些字符串，这些字符串在另一个字符串中并创建一个新的字符串：

< blockquote class =post_quotes>

astr =" Bob Carol Ted Alice"
letters =" adB"
some_func（astr，letters）
"坏

astr =" Bob Carol Ted Alice"

letters =" adB"

both = [x代表x中的x，如果x代表字母]

打印两者

[''B''，''a'' ，''d'']

On Tue，2005年4月19日13:33:17 -0700，James Stroud< js ***** @ mbi.ucla.edu>写道：

你好，

我正在寻找一种很好的方法，只从字符串中取出那些字符串
在另一个字符串中并制作一个新的字符串：

astr =" Bob Carol Ted Alice"
letters =" adB"
some_func（astr （字母）坏

我可以这样写：

astr =" Bob Carol Ted Alice"
letters =" adB"

导入集
alist = [lttr for lttr in astr if lttr in set（letters）]
newstr =""
for lttr in alist：
newstr + = lttr

但这看起来很难看。我特别不喜欢newstr + = lttr因为它每次都会成为一个新的字符串。我认为像这样的东西必须已经在某个地方使用
功能，或者我可以使用
内置工具提高效率。

任何想法？

我认为如果要修改的字符串是_very_ long，这将是值得的：

def some_func（ s，letters，table =''''。join（[chr（i）for i in xrange（256）]））：
... return s.translate（table，

...''''。join（[chr（i）for x in xrange（256）if chr（i）not in letters]）

... some_func（" Bob） Carol Ted Alice"，''adB''）

''坏''


见帮助（str.translate）


如果你想在一个循环中使用它，使用相同的字母我想要消除重复的

计算删除。你可以创建一个返回函数的工厂函数

，它使用闭包单元格中的删除。但不要过早优化;-)


问候，

Bengt Richter

Hello,

I am looking for a nice way to take only those charachters from a string that
are in another string and make a new string:

astr = "Bob Carol Ted Alice"
letters = "adB"
some_func(astr,letters)

"Bad"

I can write this like this:

astr = "Bob Carol Ted Alice"
letters = "adB"

import sets
alist = [lttr for lttr in astr if lttr in Set(letters)]
newstr = ""
for lttr in alist:
newstr += lttr

But this seems ugly. I especially don''t like "newstr += lttr" because it makes
a new string every time. I am thinking that something like this has to be a
function somewhere already or that I can make it more efficient using a
built-in tool.

Any ideas?

James

--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/

解决方案

James Stroud <js*****@mbi.ucla.edu> writes:

But this seems ugly. I especially don''t like "newstr += lttr" because it makes
a new string every time. I am thinking that something like this has to be a
function somewhere already or that I can make it more efficient using a
built-in tool.

"".join

''as

James Stroud wrote:

Hello,

I am looking for a nice way to take only those charachters from a string that
are in another string and make a new string:

astr = "Bob Carol Ted Alice"
letters = "adB"
some_func(astr,letters)
"Bad"

astr = "Bob Carol Ted Alice"
letters = "adB"
both = [x for x in astr if x in letters]
print both

[''B'', ''a'', ''d'']

On Tue, 19 Apr 2005 13:33:17 -0700, James Stroud <js*****@mbi.ucla.edu> wrote:

Hello,

I am looking for a nice way to take only those charachters from a string that
are in another string and make a new string:

astr = "Bob Carol Ted Alice"
letters = "adB"
some_func(astr,letters)"Bad"

I can write this like this:

astr = "Bob Carol Ted Alice"
letters = "adB"

import sets
alist = [lttr for lttr in astr if lttr in Set(letters)]
newstr = ""
for lttr in alist:
newstr += lttr

But this seems ugly. I especially don''t like "newstr += lttr" because it makes
a new string every time. I am thinking that something like this has to be a
function somewhere already or that I can make it more efficient using a
built-in tool.

Any ideas?

James

I think this will be worth it if your string to modify is _very_ long:

def some_func(s, letters, table=''''.join([chr(i) for i in xrange(256)])): ... return s.translate(table,
... ''''.join([chr(i) for i in xrange(256) if chr(i) not in letters]))
... some_func("Bob Carol Ted Alice", ''adB'')

''Bad''

see help(str.translate)

If you want to use it in a loop, with the same "letters" I''d want to eliminate the repeated
calculation of the deletions. You could make a factory function that returns a function
that uses deletions from a closure cell. But don''t optimize prematurely ;-)

Regards,
Bengt Richter

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