Return several values from a matching function using a dictionary with python

Question

I am in the process of developing a small script which allows me to retrieve the values of a dictionary if the condition is met.

if the condition is fulfilled I retrieve the key of the dictionary in the cell of my columns in my dataframe.

However, where I get stuck is that I can only retrieve one value from my dictionary while my initial values validate other conditions.

what i have :

Name	shopping list	cat_and_subcat
tom	apple , sirop , carotte	Fruit - Apple
nick	chocolate, banana, apple minie	Cake - Oreo
julie	juice	Fruit - Lemon

what i should have :

Name	shopping list	cat_and_subcat
tom	apple , sirop , carotte	Fruit-Apple , Cake-Carote cake
nick	chocolate, banana, apple minie	Cake - Oreo , Fruit - Apple
julie	juice	Fruit - Lemon

How do I get to return all the values of the conditions that are true in the same cell?

# Import  library
import pandas as pd
import re

# initialize list of lists
data = [
    ["tom", "apple , sirop , carotte"],
    ["nick", "chocolate, banana, apple minie"],
    ["julie", "juice"],
]

# Create the pandas DataFrame
df = pd.DataFrame(data, columns=["Name", "shopping list"])

# print dataframe.
df


def create_dict():
    # Separator
    sep = " - "
    # cat
    fruit = "Fruit"
    cake = "Cake"
    # sub cat
    apple = "Apple"
    lemon = "Lemon"
    oreo = "Oreo"
    carote_cake = "Carote cake"

    category_uri_dict_reg_match = {
        fruit: {
            apple: ["apple", "apple minie"],
            lemon: ["juice"],
        },
        cake: {
            carote_cake: ["carotte", "betacarotten"],
            oreo: ["chocolate", "crunchy cake"],
        },
    }

    # compile regexp one for all for performance matters
    category_dict_reg_match = {}
    for cat, cat_dict in category_uri_dict_reg_match.items():
        category_dict_reg_match[cat] = {}
        for sub_cat, raw_reg_list in cat_dict.items():
            reg_list = []
            for raw_regex in raw_reg_list:
                reg_list.append(re.compile(raw_regex))
            # print(reg_list)
            category_dict_reg_match[cat][sub_cat] = reg_list
    return category_dict_reg_match


dictio = create_dict()


def get_cat_and_subcat(topic):
    topic = re.sub("", "", topic)
    for cat, cat_dict in dictio.items():
        for sub_cat, reg_list in cat_dict.items():
            if any(compiled_reg.match(topic) for compiled_reg in reg_list):
                return cat + sep + sub_cat
    return "NO_MATCH"


df["cat_and_subcat"] = df.apply(
    lambda x: get_cat_and_subcat(x["shopping list"]), axis=1
)

df

Your code specifically returns as soon as it finds the first match. You have to accumulate the matches in a list or other structure. When you finish the loop, then you return the list. Look for a secondary tutorial on functions, or simply search how to return multiple values. — Prune
– Prune, Commented Feb 25, 2021 at 18:18

abysslover · Accepted Answer · 2021-02-25 18:25:59Z

1

match tries to find a match only at the beginning of the string, while search checks for a match anywhere in the string (this is what Perl does by default) in Python. In addition, your code returns instantly if it finds a match. You can modify your code as follows:

def get_cat_and_subcat(topic):
    sep = " - "
    topic = re.sub("", "", topic)
    results = []
    for cat, cat_dict in dictio.items():
        for sub_cat, reg_list in cat_dict.items():
            if any(compiled_reg.search(topic) for compiled_reg in reg_list):
                results.append(cat + sep + sub_cat)
    if 0 == len(results):
        return "NO_MATCH"
    return ", ".join(results)

Result:

    Name                   shopping list
0    tom         apple , sirop , carotte
1   nick  chocolate, banana, apple minie
2  julie                           juice
    Name                   shopping list                     cat_and_subcat
0    tom         apple , sirop , carotte  Fruit - Apple, Cake - Carote cake
1   nick  chocolate, banana, apple minie         Fruit - Apple, Cake - Oreo
2  julie                           juice                      Fruit - Lemon

answered Feb 25, 2021 at 18:25

abysslover

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1 Comment

luigi lorenzano Over a year ago

it works great, the mistake I made was forgetting the append function and a bad use of .match(). it will not happen twice thank you very much for your intervention. It helps me enormously to understand.

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