How to retrieve minimum unique values from list?

Assuming input data you can do classic sql-ish groupby:

from itertools import groupby

# in case your data is sorted already by api skip the below line
data = sorted(data, key=lambda x: x['api'])

res = [
    {'api': g, 'result': min(v, key=lambda x: x['result'])['result']} 
    for g, v in groupby(data, lambda x: x['api'])
]

Outputs:

[{'api': 'test1', 'result': 0}, {'api': 'test2', 'result': 1}, {'api': 'test3', 'result': 0}]

You can pass through the list once and preserve the best ones you see for each group. This is time and space efficient.

def get_min_unique(items, id_key, value_key):
  lowest = {}
  for item in items:
    key = item[id_key]
    if key not in lowest or lowest[key][value_key] > item[value_key]:
        lowest[key] = item
  return list(lowest.values())

For example with your own data:

data = [
  {'api':'test1', 'result': 0},
  {'api':'test2', 'result': 1},
  {'api':'test3', 'result': 2},
  {'api':'test3', 'result': 0},
  {'api':'test3', 'result': 1},
]

assert get_min_unique(data, 'api', 'result') == [
  {'api': 'test1', 'result': 0},
  {'api': 'test2', 'result': 1},
  {'api': 'test3', 'result': 0},
]