Sorting a list of dictionaries by dictionary key

[Eric Deveaud]

Nico Grubert wrote:
>  Hi there,
> 
>  I am looking for a way to sort a list containing dictionaries.
> 
>  This is my example list:
>  [{'Title': 'ABC', 'from_datetime': DateTime('2006/04/25 12:45:00 
>  GMT+2')}, {'Title': 'DEF', 'from_datetime': DateTime('2006/04/18 
>  12:45:00 GMT+2')}, {'Title': 'GHI', 'from_datetime': 
>  DateTime('2006/03/10 12:45:00 GMT+2')}]
> 
>  I want to sort the list by dictionary's key 'from_datetime' so the 
>  sorted list should be:
> 
>  [{'Title': 'GHI', 'from_datetime': DateTime('2006/03/10 12:45:00 
>  GMT+2')}, {'Title': 'DEF', 'from_datetime': DateTime('2006/04/18 
>  12:45:00 GMT+2')}, {'Title': 'ABC', 'from_datetime': 
>  DateTime('2006/04/25 12:45:00 GMT+2')}]
> 
>  Any idea how I can sort this list?

sort can take a comparaison function. which specification are 
takes 2 elements 
returns a negative value if elem1 is lesser than elem2
returns  a positive value if elem1 is grater than elem2
returns zero if elem1 == elem2

you may write such fuction

def dictionary_datetime_sorter(d1, d2):
	date1 = d1['from_datetime']
	date2 = d2['from_datetime']
	if date1 < date2: return -1
	elif date1 > date2: return 1
	else: return 0

you'll have to find out how to compare 2 DateTime

and then, in order to sort your list
your_dictionary_list.sort(dictionary_datetime_sorter)


	Eric
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