I have a list of dictionaries
lst = [ {'x': 1, 'y': 2}, {'x': 1, 'y': 3 }, {'x': 2, 'y': 2 } ]
Dictionaries always have the same keys and it is the values that change at all times.
Then I would like to add the value of the keys "and" when the key "x" has the same value.
The output would have to give: lst # [{'x': 1, 'y': 5 }, {'x': 2, 'y': 2 }].
One option is to use itertools.groupby to group the dictionaries according to the value of the key 'x' . Done this it is simple to use compression of lists to obtain the final list, adding the values of the key 'y' (and also other keys if they exist):
import itertools
from operator import itemgetter
lst = [{'x': 1, 'y': 2}, {'x': 1, 'y': 3 }, {'x': 2, 'y': 2 }]
grupos = itertools.groupby(sorted(lst, key=itemgetter('x')), key=itemgetter('x'))
res = [{'x': v, 'y': sum(dicc['y'] for dicc in diccs)} for v, diccs in grupos]
print(res)
The output is [{'x': 1, 'y': 5}, {'x': 2, 'y': 2}] .
Another alternative solution:
from collections import defaultdict
lst = [{'x': 1, 'y': 2}, {'x': 1, 'y': 3 }, {'x': 2, 'y': 2 }]
aux = defaultdict(int)
for d in lst:
aux[d['x']] += d['y']
res = [{'x':k, 'y':v} for (k,v) in res.items()]
I have solved the problem, just like that.
lst = [ {'x': 1, 'y': 2}, {'x': 1, 'y': 3 }, {'x': 2, 'y': 2 } ]
result_list = []
name_dict = {}
for dict_item in lst:
x = dict_item['x']
y = dict_item['y']
if x in name_dict:
pos = name_dict[x]
result_list[pos] = {'x':x, 'y': (result_list[pos]['y']+y)}
else:
result_list.append(dict_item)
name_dict[x] = len(result_list) - 1
print result_list