python中的双循环
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double for loops in python
提问by Vijay
I am trying to get a list of file names in order. Something like
我正在尝试按顺序获取文件名列表。就像是
files-1-loop-21
files-1-loop-22
files-1-loop-23
files-1-loop-24
files-2-loop-21
files-2-loop-22
files-2-loop-23
.
.
.
and so on
As for testing I have written python code as below:
至于测试，我编写了如下python代码：
code sample_1:
代码示例_1：
for md in range(1,5):
for pico in range(21,25):
print md, pico
It gives me pair of number such as:
它给了我一对数字，例如：
`1 21
1 22
1 23
1 24
2 21
2 22
2 23
2 24
3 21
3 22
3 23
3 24
4 21
4 22
4 23
4 24
`
`
if I use:
如果我使用：
code sample_2:
代码示例_2：
for md in range(1,5):
for pico in range(21,25):
print "file-md-loop-pico"
I get
我得到
files-md-loop-pico
files-md-loop-pico
files-md-loop-pico
files-md-loop-pico
files-md-loop-pico
files-md-loop-pico
files-md-loop-pico
How (code sample_2) should be altered to get the file lists as I wanted (as shown in the beginning of this post) in python?
应该如何更改（代码示例_2）以在 python 中获取我想要的文件列表（如本文开头所示）？
Thanks in advance.
提前致谢。
Regards
问候
采纳答案by Artsiom Rudzenka
Try this:
尝试这个：
for md in range(1,5):
for pico in range(21,25):
print "file-{0}-loop-{1}".format(md, pico)
Or:
或者：
from itertools import product
for md, pico in product(range(1,5), range(21,25)):
print "file-{0}-loop-{1}".format(md, pico)
回答by Volatility
Use string formatting.
使用字符串格式。
print 'file-{0}-loop-{1}'.format(md, pico)
回答by AlexFoxGill
1) Python scope is determined by indentation. Your inner code must be properly indented:
1) Python 范围由缩进决定。您的内部代码必须正确缩进：
for md in range(1,5):
for pico in range(21,25):
print "file-md-loop-pico"
2) You are using a string literal "file-md-loop-pico"rather than inserting your variables mdand pico. To format your string correctly, use:
2）您使用的是字符串文字，"file-md-loop-pico"而不是插入变量md和pico. 要正确格式化字符串，请使用：
for md in range(1,5):
for pico in range(21,25):
print "file-{0}-loop-{1}".format(md, pico)
回答by Peter Wooster
The solution, provided in the other answers,with arguments surrounded by {} is the correct modern way to do this
解决方案，在其他答案中提供，参数被 {} 包围是正确的现代方法
print'file-{0}-loop-{1}'.format{md,poco)
There is an older way to do this that you will probably see, and that might make more sense if you are familiar with c or c++ sprintf
您可能会看到一种较旧的方法来执行此操作，如果您熟悉 c 或 c++ sprintf，这可能更有意义
print'file-%d-loop-%d'%(md,poco)
The documentation: http://docs.python.org/2/tutorial/inputoutput.html
回答by vtlinh
one-liner:
单线：
print '\n'.join([('files-%d-loop_%d' %(i, j)) for i in xrange(1,5) for j in xrange(21,25)])
回答by DEBLEEN BISWAS
This will solve the problem easily:
这将轻松解决问题：
Code:
代码：
for md in range(1,5):
for pico in range(21,25):
print "file-%d-loop-%d"%(md,pico)
Output:
输出：
file-1-loop-21
file-1-loop-22
file-1-loop-23
file-1-loop-24
file-2-loop-21
file-2-loop-22
file-2-loop-23
file-2-loop-24
file-3-loop-21
file-3-loop-22
file-3-loop-23
file-3-loop-24
file-4-loop-21
file-4-loop-22
file-4-loop-23
file-4-loop-24
回答by Sandeep Gupta
for md in range(1,5,1):
for pico in range(21,25,1):
print ("file-" + str(md) +"-loop-" + str(pico) )
