select dictionary item with min value in array of dictionary elements in python 2.7

Question

I have an array of dictionary elements like this:

d = [{'k': 'k1', 'v':4}, {'k': 'k2', 'v':5}, {'k': 'k3', 'v':2}]

I would like to retrieve a value of 'k' from the the dictionary element with lowest 'v', there may be more than one with the same lowest value. In the case of the example above, I would like to get:

['k3']

This is what what I have so far, is this the most efficient and pythonic way of solving the problem (besides collapsing the two lines into one)?

m = min([x['v'] for x in d])                               
r = [x['k'] for x in d if x['v'] == m]

Thanks.

k3 is not one of your keys.

juanchopanza
– juanchopanza

2014-04-20 14:17:55 +00:00
Commented Apr 20, 2014 at 14:17 — juanchopanza
– juanchopanza, Commented Apr 20, 2014 at 14:17
Sorry I was not clear - I edited to be more exact

IUnknown
– IUnknown

2014-04-20 14:31:40 +00:00
Commented Apr 20, 2014 at 14:31 — IUnknown
– IUnknown, Commented Apr 20, 2014 at 14:31

Paul Draper · Accepted Answer · 2014-04-20 15:06:26Z

2

Remove the unnecessary list comprehension and use a generator expression instead.

m = min(x['v'] for x in d)                               
r = [x['k'] for x in d if x['v'] == m]

But is there a reason you are keeping a list of key-value pairs, rather than a dict? (To have a multimap?)

d = {'k1':4, 'k2':5, 'k3':2}
m = min(d.itervalues())                        
r = [k for k, v in d.iteritems() if v == m]

edited Apr 20, 2014 at 15:06

answered Apr 20, 2014 at 14:21

Paul Draper

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2 Comments

IUnknown Over a year ago

The list of dictionaries is what I am given to work with form another part of the system, I would like to just retrieve a value of 'k' from the the dictionary element with lowest 'v', there may be more than one with the same lowest value.

Paul Draper Over a year ago

@IUnknown, if possible, if d is meant simply to be a list of keys and values, I would recommended changing that part of the system (if possible) to use a dict.

Mahesh Yellai · Accepted Answer · 2014-04-20 15:51:03Z

0

r = min(d, key=lambda x: x["v"])["k"]

This should give you 'k3'

answered Apr 20, 2014 at 15:51

Mahesh Yellai

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