如何在python中组合多个集合的元素？

Question

I am trying to work out how to combine two collections together. In my code, I have a list (2D) with some information, the array looks like:

array = [ 
["peter", "peter.com"],
["jake, "jake.com"],
["simon, "simon.com"]
]

Also I have multiple dictionaries. Every dictionary is created by function with URL as the input eg: function(URL) . For the first item in the array lets make the result like:

def function(url)
released = {
        "burger" : 200,
        "pasta" : 120,
        "thai" : 70,
}
return(relased)

The point where I struggle is, I would like to combine these two collections together in list like this:

new_list = [ 
[peter, peter.com, burger, 200], 
[peter, peter.com, pasta, 120], 
[peter, peter.com, thai, 70], 
[jake, jake.com, item_1, price_1], 
[jake, jake.com, item_2, price_2]
....
]

I am also adding visualisation in case it will help:

Which is the proper way how to achieve this? I tried using for, but obviously it leads to malfunction:

for index, row in enumerate(array):
    new_list.append([])
    new_list[index].append(row[0])
    new_list[index].append(row[1])
    for x, y in function(row[0]).items():
        new_list[index].append(x)
        new_list[index].append(y)

generates

new_list = [ 
[name_1, URL_1, item_1, price_1, item_2, price_2, item_3, price_3], 
[name_2, URL_2, item_1, price_1, item_2, price_2]
]

Answer 1

You should be looking at something like this:

new_list = []
for name, URL in array:
    for item, price in function(URL).items():
        new_list.append([name, URL, item, price])

Or you can do it in one list comprehension:

new_list = [[name, URL, item, price] for name, URL in array for item, price in function(URL).items()]

Test:

array = [
    ['name1', 'URL1'],
    ['name2', 'URL2']
    ]

def function(URL):  # mock function to return dictionary
    return {f'item{i}': f'price{i}' for i in range(1, 4 if URL == 'URL1' else 3)}

new_list = [[name, URL, item, price] for name, URL in array for item, price in function(URL).items()]

pprint(new_list)

Output:

[['name1', 'URL1', 'item1', 'price1'],
 ['name1', 'URL1', 'item2', 'price2'],
 ['name1', 'URL1', 'item3', 'price3'],
 ['name2', 'URL2', 'item1', 'price1'],
 ['name2', 'URL2', 'item2', 'price2']]

Answer 2

You can use a combination of itertools.groupby , itertools.chain and operator.itemgetter in a comprehension.

from itertools import groupby, chain
from operator import itemgetter

new_list = [ 
    ['name_1', 'URL_1', 'item_1', 'price_1'], 
    ['name_1', 'URL_1', 'item_2', 'price_2'], 
    ['name_1', 'URL_1', 'item_3', 'price_3'], 
    ['name_2', 'URL_2', 'item_1', 'price_1'], 
    ['name_2', 'URL_2', 'item_2', 'price_2']]

key = itemgetter(slice(None, 2))
result = [list(chain(k, *(i[2:] for i in g))) for k, g in groupby(new_list, key)]

print(result)

Results:

[['name_1', 'URL_1', 'item_1', 'price_1', 'item_2', 'price_2', 'item_3', 'price_3'],
 ['name_2', 'URL_2', 'item_1', 'price_1', 'item_2', 'price_2']]

Answer 3

I would suggest using pandas dataframes and join them together, for that, you have to create a dataframe from your list as follows:

df1 = pd.DataFrame(my_list, columns=['name', 'URL']) 

also, create a dataframe from your dictionary as follows:

df2 = pd.DataFrame.from_dict(my_dict)

Then, if you have the URL column in both dataframes (which I understood from the comments), you have to join them:

result = df1.join(df2, on='URL')