List of dictionary to an expression

Question

Python v3.4.3

Given list of dictionaries:

dlist = [{'Bilbo':'Ian','Frodo':'Elijah'},{'Bilbo':'Martin','Thorin':'Richard'}]

and a variable k

k = 'Frodo'

Task is to write an expresion to asign list from dictionary, where key doesn't exist must be shown 'not present', all problem must be solved in 1 line.

I have written line that gives desirable output :

for kk in dlist : kk[k] if k in kk else 'NOT PRESENT'

the output:

'Elijah'
'NOT PRESENT'

but the problem is that I can't assign this output to variable

res = list(for kk in dlist : kk[k] if k in kk else 'NOT PRESENT')

or

res = [for kk in dlist : kk[k] if k in kk else 'NOT PRESENT']

EDIT: In addition this gives correct assignment if all dictionaries have desired key

res = [x[k] for x in dlist]

but I cant combine dictionary[key] if 'key' in dictionary

with for kk in dictionarylist

After abhinsit answered this question and gave me some insights: I've solved it without .get

output = [item[k] if k in item else 'NOT PRESENT' for item in dlist]

The main problem for me was the correct position of else statement.

Briefly: that is not the proper syntax for a comprehension, which is what you're looking for. See the linked duplicate. — TigerhawkT3, Apr 26 '16 at 05:55
Your question would be much clearer if you provided the expected result (not the output when printing). Also, remove the "Python343" from the title, that's what the separate tags are for. — Ulrich Eckhardt, Apr 26 '16 at 05:55
Removed Python343 from title and gave expected result without condition(if) — lescijus, Apr 26 '16 at 06:05

score 2 · Accepted Answer · answered Apr 26 '16 at 05:56

2

>>> dlist = [{'Bilbo':'Ian','Frodo':'Elijah'},{'Bilbo':'Martin','Thorin':'Richard'}]
>>> required_key = 'Frodo'
>>> output = [item.get(required_key,'NOT PRESENT')for item in dlist]
>>> output
['Elijah', 'NOT PRESENT']
>>>

answered Apr 26 '16 at 05:56

abhinsit

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Ty for your answer it gives desirable result, but the same task is doable without using item.get. – lescijus Apr 26 '16 at 06:07
yes there are different ways to get / check value in a dictionary, it all depends how you want to implement it. You may have written a if instead of get – abhinsit Apr 26 '16 at 06:13
Yes the problem for me was that else is mandatory, and else position must be not at the very end, with your advise I get desirable output with if [item[k] if k in item else 'NOT PRESENT' for item in dlist] – lescijus Apr 26 '16 at 06:17

List of dictionary to an expression

1 Answers1