How to sum values from an list of dictionaries?-CodePudding

So, I want to sum multiple values of a list of dictionaries, this is what I made so far, it works but obviously there is a lot of problems and inefficiency.

# plate: license plate of the vehicule
# distance: the distance traveled by the vehicule in KM
# time: the time the vehicule travels in minutes
from collections import defaultdict
vehicles = [
    {"plate":"ABC123", "distance":80.3, "time":180},
    {"plate":"ABC123", "distance":80.3, "time":180},
    {"plate":"XYZ246", "distance":40.0, "time":30},
    {"plate":"XYZ246", "distance":60.7, "time":100},
    {"plate":"ABC123", "distance":70.2, "time":200},
    {"plate":"MNL357", "distance":40.3, "time":70}
]
returnList = []
dst, time = defaultdict(int), defaultdict(int)

for v in vehicles:
    dst[v["plate"]]  = v["distance"]
    time[v["plate"]]  = v["time"]

dst = dict(dst)
time = dict(time)

for i in dst:
    returnList.append({"plate":i,"distance":dst[i], "time":time[i]})

print(returnList)

In this case, I want to sum the distance and time of a license plate, the results are:

[
  {'plate': 'ABC123', 'distance': 230.8, 'time': 560},
  {'plate': 'XYZ246', 'distance': 100.7, 'time': 130},
  {'plate': 'MNL357', 'distance': 40.3, 'time': 70}
]

CodePudding user response：

You could do this:

In [6]: from collections import defaultdict
   ...: vehicles = [
   ...:         {"plate":"ABC123", "distance":80.3, "time":180},
   ...:         {"plate":"ABC123", "distance":80.3, "time":180},
   ...:         {"plate":"XYZ246", "distance":40.0, "time":30},
   ...:         {"plate":"XYZ246", "distance":60.7, "time":100},
   ...:         {"plate":"ABC123", "distance":70.2, "time":200},
   ...:         {"plate":"MNL357", "distance":40.3, "time":70}
   ...:     ]

In [7]: import itertools as it

In [8]: keyfunc = lambda x: x['plate']

In [9]: vehicle_groups = it.groupby(sorted(vehicles, key=keyfunc), keyfunc)

In [10]: [{'plate':p, 'distance':sum(x['distance'] for x in g), 'time':sum(y['ti
    ...: me'] for y in g)} for p, g in vehicle_groups]
Out[10]: 
[{'plate': 'ABC123', 'distance': 230.8, 'time': 0},
 {'plate': 'MNL357', 'distance': 40.3, 'time': 0},
 {'plate': 'XYZ246', 'distance': 100.7, 'time': 0}]

CodePudding user response：

Could you expand on what result you're trying to get? Bit unclear.