值得翻转字典 [英] Worthwhile to reverse a dictionary

问题描述

我刚开始搞乱编程并开始使用Python。部分

我的第一个项目涉及将数值转换为字母。

我希望能够反向执行，字母到数字，

一种用于查找的表和一种用于反向查找的表。我认为

字典是要使用的结构 - 写一次并在第二个实例中交换键的值和值的键。但是，翻译一本字典的
似乎并不容易实现。我使用

错误的数据结构吗？

解决方案

ru ********* @ hotmail.com 写道：

我刚刚开始搞乱编程并开始用Python。我的第一个项目部分涉及将数值转换为字母。
我希望能够反向执行，字母转换为数字，
排序查找表格和用于反向查找的表。我想
字典将是使用的结构 - 只需编写一次，然后在第二个实例中交换密钥的值和值的键。但是，翻译字典似乎并不容易实现。我是否使用了错误的数据结构？

原始问题可能有更好的解决方案（如果你发布了

更多细节我肯定​​会有很多建议），但

以下应该反转字典..

< blockquote class =post_quotes> testdict = dict（a = 1，b = 2）
reversedict = dict（键，键值），

中的值

< br $> b $ b testdict.iteritems（））

麦克古根将会是什么？b $ b -
http://www.willmcgugan.com

"" .join（{''*' '：'''''，''^''：''。''}。得到（c，0）或chr（97+（ord（c）-84）％26）for

" jvyy * jvyyzpthtna ^ pbz"）

非常感谢。这似乎有它。这是我以前用过
的那种东西：

＃！/ usr / local / bin / python


＃make一个简短的字典

d1 = {''A''：''1''，''B''：''2''，''C''：''3''}


d1.keys（）中的字母：打印字母，''\ t''，d1 [letter]


＃make 2个字典的输出之间的空格

print''\ n''

＃反转第一个字典中的键和值

＃从这一点开始尝试很多东西，关于我取得的最好成绩是

＃获取打印d1时显示的最后一个键/值对

＃这是正确的反转，但只有一对

d2 = {d1 [letter]：letter}


为d2.keys（）中的num：print num，' '\t''，d2 [num]

显示

A 1

C 3

B 2


2 B

" d1 = {''A''：''1''，''B''：''2''，''C''：''3''}"


和


" d1 = dict（A = 1，B = 2，C = 3） ？


我看到的所有字典示例（python.org，aspn.activestate.com，

由Lutz学习Python等）使用d = {''x''：''y''}。

I just started messing with programming and started with Python. Part
of my first project deals with translating numerical values to letters.
I would like to be able to do the reverse as well, letters to numbers,
sort of a table for lookup and a table for reverse lookup. I thought
that a dictionary would be the structure to use- write it once and in a
second instance swap the keys for values and values for keys. However,
reversing a dictionary does not seem to be easily achieved. Am I using
the wrong data structure?

解决方案

ru*********@hotmail.com wrote:

I just started messing with programming and started with Python. Part
of my first project deals with translating numerical values to letters.
I would like to be able to do the reverse as well, letters to numbers,
sort of a table for lookup and a table for reverse lookup. I thought
that a dictionary would be the structure to use- write it once and in a
second instance swap the keys for values and values for keys. However,
reversing a dictionary does not seem to be easily achieved. Am I using
the wrong data structure?

There may be a better solution to your original problem (if you post
more details Im sure there will be plenty of suggestions), but the
following should reverse a dictionary..

testdict = dict(a=1, b=2)
reversedict = dict( (value, key) for key, value in

testdict.iteritems() )

Will McGugan
--
http://www.willmcgugan.com
"".join({''*'':''@'',''^'':''.''}.get(c,0) or chr(97+(ord(c)-84)%26) for c in
"jvyy*jvyyzpthtna^pbz")

Thanks so much. That seems to have it. This is the sort of thing I
had before:
#!/usr/local/bin/python

# make a short dictionary
d1 = {''A'' : ''1'', ''B'' : ''2'', ''C'' : ''3''}

for letter in d1.keys(): print letter, ''\t'', d1[letter]

# make a space between the output of the 2 dictionaries
print ''\n''
# reverse the keys and values from the first dictionary
# from this point many things were tried, about the best I achieved was
# getting the last key/value pair as displayed when printing the d1
# it was properly reversed but there was only one pair
d2 = {d1[letter] : letter}

for num in d2.keys(): print num, ''\t'', d2[num]
This displays
A 1
C 3
B 2

2 B

What is the difference between

" d1 = {''A'' : ''1'', ''B'' : ''2'', ''C'' : ''3''} "

and

" d1 = dict(A = 1, B = 2, C = 3) " ?

All of the dictionary examples I saw (python.org, aspn.activestate.com,
Learning Python by Lutz, among others) use d={''x'' : ''y''}.

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