列表中的字典：.update（）的条件更新

Question

I am trying to update dictionaries in a list nodes with tuples in another list source with a conditional.

Tuple list:

source = [('144 IV 285', 16),
 ('144 IV 1', 11),
 ('141 IV 155', 7)]

Dictionary list:

nodes = [{'id': '144 IV 285','date': '2018-08-15','relevancy': 10, 'outDegree': 18},
{'id': '144 IV 240','date': '2016-08-15','relevancy': 4, 'outDegree': 10}]

Each item in 'nodes' should be extended by a new key ( inDegree ) value pair based on the 'source' list. My code:

for item in sources:
    for item2 in nodes:
        if item2["id"] == item[0]:
            item2.update( {"inDegree": item[1]})
        else:
            item2.update( {"inDegree": 0})

Problem: How can I populate the key inDegree either by the value in the source list or 0, if there is no matching id for an item in 'nodes' in the 'source' list?

Answer 1

Problem is that it is iterating source even after there was a match, and thus overwrite the previous update. You can unpack your source and do comparison:

for item2 in nodes:
    sources = list(zip(*source))
    if item2["id"] in sources[0]:
        item2.update({"inDegree": sources[1][sources[0].index(item2["id"])]})
    else:
        item2.update({"inDegree": 0})

print(nodes)
[{'id': '144 IV 285',
  'date': '2018-08-15',
  'relevancy': 10,
  'outDegree': 18,
  'inDegree': 16},
 {'id': '144 IV 240',
  'date': '2016-08-15',
  'relevancy': 4,
  'outDegree': 10,
  'inDegree': 0}]

Answer 2

Try this:

for item in nodes:
    for item2 in source:
        if item["id"] == item2[0]:
            item.update( {"inDegree": item2[1]})
            break
        else:
            item.update( {"inDegree": 0})