Merging two dictionaries in Python?

Question

I want to merge this dictionary:

b = {data:[{station_id: 7000,
     name: "Ft. York / Capreol Crt."
     },
     {station_id: 7001,
      name: "Lower Jarvis St / The Esplanade"}
     ]}

and this one :

c = {data:[{station_id: 7000,
     num_bikes_available: 18,
     },
     {station_id: 7001,
      num_bikes_available: 4,
      }
    ]}

and get one dictionary like this:

d = {data:[{station_id: 7000,
 name: "Ft. York / Capreol Crt.",
 num_bikes_available: 18
 },
{station_id: 7001,
 name: "Lower Jarvis St / The Esplanade",                         
 num_bikes_available: 4}
]}

How can I do that?

Answer 1

For Py>3.5:

It's easy. Just enter:

d = {**b, **c}

Answer 2

The key to this problem is picking the right data structure. Instead of b['data'] being a list, it should be a dict indexed by the merge key. The following code first converts b and c into dicts indexed by station_id, then merges those dictionaries.

Try this:

from pprint import pprint

b = {'data': [{'station_id': 7000,
     'name': "Ft. York / Capreol Crt."
     },
     {'station_id': 7001,
      'name': "Lower Jarvis St / The Esplanade"},
     {'station_id':7002,'num_bikes_available':10},
     ]}

c = {'data': [{'station_id': 7000,
     'num_bikes_available': 18,
     },
     {'station_id': 7001,
      'num_bikes_available': 4,
      }
    ]}

# First, convert B and C to a more useful format:

b1 = {item['station_id']: item for item in b['data']}
c1 = {item['station_id']: item for item in c['data']}

# Now construct D by merging the individual values
d = {'data': []}
for station_id, b_item in sorted(b1.items()):
    z = b_item.copy()
    z.update(c1.get(station_id, {}))
    d['data'].append(z)

pprint(d)