迭代两个dicts列表并创建没有循环的元组列表

Question

I have two lists of dicts: list1 and list2 .

print(list1)
[{'name': 'fooa', 'desc': 'bazv', 'city': 1, 'ID': 1},
 {'name': 'bard', 'desc': 'besd', 'city': 2, 'ID': 1},
 {'name': 'baer', 'desc': 'bees', 'city': 2, 'ID': 1},
 {'name': 'aaaa', 'desc': 'bnbb', 'city': 1, 'ID': 2},
 {'name': 'cgcc', 'desc': 'dgdd', 'city': 1, 'ID': 2}]

print(list2)
[{'name': 'foo', 'desc': 'baz', 'city': 1, 'ID': 1},
 {'name': 'bar', 'desc': 'bes', 'city': 1, 'ID': 1},
 {'name': 'bar', 'desc': 'bes', 'city': 2, 'ID': 1},
 {'name': 'aaa', 'desc': 'bbb', 'city': 1, 'ID': 2},
 {'name': 'ccc', 'desc': 'ddd', 'city': 1, 'ID': 2}]

I need a list of tuples that will hold two paired dicts (one dict from each list) with the same city and ID .

I did it with double loop:

list_of_tuples = []
for i in list1:
    for j in list2:
        if i['ID'] == j['ID'] and i['city'] == j['city']:
            list_of_tuples.append((i, j))
print(list_of_tuples)

[({'name': 'fooa', 'desc': 'bazv', 'city': 1, 'ID': 1},
  {'name': 'foo', 'desc': 'baz', 'city': 1, 'ID': 1}),
 ({'name': 'fooa', 'desc': 'bazv', 'city': 1, 'ID': 1},
  {'name': 'bar', 'desc': 'bes', 'city': 1, 'ID': 1}),
 ({'name': 'bard', 'desc': 'besd', 'city': 2, 'ID': 1},
  {'name': 'bar', 'desc': 'bes', 'city': 2, 'ID': 1}),
 ({'name': 'baer', 'desc': 'bees', 'city': 2, 'ID': 1},
  {'name': 'bar', 'desc': 'bes', 'city': 2, 'ID': 1}),
 ({'name': 'aaaa', 'desc': 'bnbb', 'city': 1, 'ID': 2},
  {'name': 'aaa', 'desc': 'bbb', 'city': 1, 'ID': 2}),
 ({'name': 'aaaa', 'desc': 'bnbb', 'city': 1, 'ID': 2},
  {'name': 'ccc', 'desc': 'ddd', 'city': 1, 'ID': 2}),
 ({'name': 'cgcc', 'desc': 'dgdd', 'city': 1, 'ID': 2},
  {'name': 'aaa', 'desc': 'bbb', 'city': 1, 'ID': 2}),
 ({'name': 'cgcc', 'desc': 'dgdd', 'city': 1, 'ID': 2},
  {'name': 'ccc', 'desc': 'ddd', 'city': 1, 'ID': 2})]

Question: How to do this in a more pythonic way (without loops)?

Answer 1

You can use itertools.product and filter :

from itertools import product


list1 = [{'name': 'fooa', 'desc': 'bazv', 'city': 1, 'ID': 1},
         {'name': 'bard', 'desc': 'besd', 'city': 2, 'ID': 1},
         {'name': 'baer', 'desc': 'bees', 'city': 2, 'ID': 1},
         {'name': 'aaaa', 'desc': 'bnbb', 'city': 1, 'ID': 2},
         {'name': 'cgcc', 'desc': 'dgdd', 'city': 1, 'ID': 2}]

list2 = [{'name': 'foo', 'desc': 'baz', 'city': 1, 'ID': 1},
         {'name': 'bar', 'desc': 'bes', 'city': 1, 'ID': 1},
         {'name': 'bar', 'desc': 'bes', 'city': 2, 'ID': 1},
         {'name': 'aaa', 'desc': 'bbb', 'city': 1, 'ID': 2},
         {'name': 'ccc', 'desc': 'ddd', 'city': 1, 'ID': 2}]

def condition(x):
    return x[0]['ID'] == x[1]['ID'] and x[0]['city'] == x[1]['city']

list_of_tuples = list(filter(condition, product(list1, list2)))

Answer 2

This is a problem well suited for pandas . If you convert the lists to DataFrames, matching the records on ID and city is the same as an inner join of the two DataFrames .

import pandas as pd

# convert lists to DataFrames
df1 = pd.DataFrame(list1)
df2 = pd.DataFrame(list2)

# merge the two DataFrames
print(df1.merge(df2, on=["ID", "city"]))
#   ID  city desc_x name_x desc_y name_y
#0   1     1   bazv   fooa    baz    foo
#1   1     1   bazv   fooa    bes    bar
#2   1     2   besd   bard    bes    bar
#3   1     2   bees   baer    bes    bar
#4   2     1   bnbb   aaaa    bbb    aaa
#5   2     1   bnbb   aaaa    ddd    ccc
#6   2     1   dgdd   cgcc    bbb    aaa
#7   2     1   dgdd   cgcc    ddd    ccc

Now you have the matched records in each row. Since the desc and name columns were present in both (and not used for the merge), they get subscripted with _x and _y to differentiate between the two souce DataFrames.

You just need to reformat it to be in your desired output. You can achieve this using to_dict and a list comprehension:

list_of_tuples = [
    (
        {"name": r["name_x"], "desc": r["desc_x"], "city": r["city"], "ID": r["ID"]},
        {"name": r["name_y"], "desc": r["desc_y"], "city": r["city"], "ID": r["ID"]}
    ) for r in df1.merge(df2, on=["ID", "city"]).to_dict(orient="records")
]

print(list_of_tuples)
#[({'ID': 1, 'city': 1, 'desc': 'bazv', 'name': 'fooa'},
#  {'ID': 1, 'city': 1, 'desc': 'baz', 'name': 'foo'}),
# ({'ID': 1, 'city': 1, 'desc': 'bazv', 'name': 'fooa'},
#  {'ID': 1, 'city': 1, 'desc': 'bes', 'name': 'bar'}),
# ({'ID': 1, 'city': 2, 'desc': 'besd', 'name': 'bard'},
#  {'ID': 1, 'city': 2, 'desc': 'bes', 'name': 'bar'}),
# ({'ID': 1, 'city': 2, 'desc': 'bees', 'name': 'baer'},
#  {'ID': 1, 'city': 2, 'desc': 'bes', 'name': 'bar'}),
# ({'ID': 2, 'city': 1, 'desc': 'bnbb', 'name': 'aaaa'},
#  {'ID': 2, 'city': 1, 'desc': 'bbb', 'name': 'aaa'}),
# ({'ID': 2, 'city': 1, 'desc': 'bnbb', 'name': 'aaaa'},
#  {'ID': 2, 'city': 1, 'desc': 'ddd', 'name': 'ccc'}),
# ({'ID': 2, 'city': 1, 'desc': 'dgdd', 'name': 'cgcc'},
#  {'ID': 2, 'city': 1, 'desc': 'bbb', 'name': 'aaa'}),
# ({'ID': 2, 'city': 1, 'desc': 'dgdd', 'name': 'cgcc'},
#  {'ID': 2, 'city': 1, 'desc': 'ddd', 'name': 'ccc'})]

Answer 3

Having nested loops is not "not pythonic". However, you can achieve the same result with a list comprehension. I don't think it's more readable though:

[(i, j) for j in list2 for i in list1 if i['ID'] == j['ID'] and i['city'] == j['city']]