Python dict to string

Question

What is correct way to convert Python dict in single string?

I have example program with code:

keywordsList = {u'[email protected]': 2, u'http://www.3ho.de/': 4, u'http://www.kundalini-yoga-zentrum-berlin.de/index.html': 1, u'[email protected]': 3}

keywordsCount = sorted(keywordsList.items(),key=lambda(k,v):(v,k),reverse=True)

for words in keywordsCount:
    print words[0], " - count: ", words[1]

so after I sort my items I get result like this:

http://www.3ho.de/  - count:  4
[email protected]  - count:  3
[email protected]  - count:  2
http://www.kundalini-yoga-zentrum-berlin.de/index.html  - count:  1

And my question is what is correct way to combine all dict stuff with cout in one single string that would look printed out something like:

'http://www.3ho.de/ : 4, [email protected] : 3, [email protected] : 2, http://www.kundalini-yoga-zentrum-berlin.de/index.html : 1'

or something similar but in logic way?

Is the sorting relevant? Do you want your output string to be sorted? — Brionius
– Brionius, Commented Aug 14, 2013 at 13:06
str(keywordsList) if you only want it as a string, and no modification to the actual dictionary? — Torxed
– Torxed, Commented Aug 14, 2013 at 13:06
yea the sorting is relevant for me, that is the reason why I don't doing that @Torxed suggestion — dzordz
– dzordz, Commented Aug 14, 2013 at 13:07

Martijn Pieters · Accepted Answer · 2013-08-14 13:08:14Z

2

Use str.join() judiciously:

', '.join([' : '.join((k, str(keywordsList[k]))) for k in sorted(keywordsList, key=keywordsList. get, reverse=True)])

Outputs:

>>> ', '.join([' : '.join((k, str(keywordsList[k]))) for k in sorted(keywordsList, key=keywordsList. get, reverse=True)])
u'http://www.3ho.de/ : 4, [email protected] : 3, [email protected] : 2, http://www.kundalini-yoga-zentrum-berlin.de/index.html : 1'

You should really look into collections.Counter() and save yourself having to sort like that. The Counter.most_common() method lists items in reverse sorted order by frequency for you.

answered Aug 14, 2013 at 13:08

Martijn Pieters

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6 Comments

Noel Evans Over a year ago

You can also drop the list you build before joining on the comma ', '.join()

Martijn Pieters Over a year ago

@NoelEvans: Using a list comprehension is more efficient than a generator expression when using str.join(). See [list comprehension without [ ], Python](list comprehension without [ ], Python)

dzordz Over a year ago

This will work for me! Thank you, will accept your answer ASAP

Noel Evans Over a year ago

@Martijn Pieters that's presumably when the size of the list you're joining on it very small. When larger, it'd be better to use a generator?

Martijn Pieters Over a year ago

@NoelEvans: No; the extra cost is in how the list object is created. The str.join() method requires a sequence (it'll iterate twice over the input) so a generator is converted to a list first. That is always going to be slower than creating list to start with with a list comprehension.

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Noel Evans · Accepted Answer · 2013-08-14 13:08:06Z

0

I'm not sure about the correct way but you could also do this:

', '.join(' : '.join([a, str(b)]) for a, b in keywordsCount)

answered Aug 14, 2013 at 13:08

Noel Evans

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1 Comment

Martijn Pieters Over a year ago

This still requires the keywordsCount list to be constructed.

user2492854 · Accepted Answer · 2014-07-22 07:25:48Z

0

use conventional methods,which are simple .This worked for me

dict = {'Alice': '2341', 'Beth': '9102', 'Cecil': '3258'}
d=" " 
for  i in dict:
 a=i
 b=dict[i]
 c=i+":"+dict[i]
 d=d+c+'\n'

print d

answered Jul 22, 2014 at 7:25

user2492854

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