Create one long string from multiple lists of strings

Question

I am writing this back-end code to filter through a dataframe using df.query(). I have two lists from which I need to make this new string which will be passed as the query. Can anyone help me out?

list1 = ['Product == "Dress"', 'Product == "Shoes"', 'City == "Mumbai"']
list2 = ['|', '&']

#expected output
new_string = "Product == "Dress" | Product == "Shoes" & City == "Mumbai""

This is my code:

res = ' '.join([' '.join(x + i for i in list2) for x in list1])
print(res)

And this is the output I am getting which is wrong:

Asked By: Roshini Prashanthica

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Source

Answer 1

This should do the trick:

' '.join(value for pair in zip(list1, list2 + ['']) for value in pair)[:-1]

Answered By: rudolfovic

Answer 2

How about creating a list of the relevant products, and using a query that check whether or not the value appear in the list, and also requiring the city to be Mumbai?

It’s cleaner and the code is easier to maintain

Filtering script:

releavnt_product = ['Dress', 'Shoes']
df.query('(Product in @releavnt_product) and (City == "Mumbai")')

Here an example:

test_data = [
        {'Product': 'product1', 'City': 'city1'},
        {'Product': 'product2', 'City': 'city2'},
        {'Product': 'Dress', 'City': 'city3'},
        {'Product': 'Dress', 'City': 'Mumbai'},
        {'Product': 'product3', 'City': 'city2'},
        {'Product': 'Shoes', 'City': 'city2'},
        {'Product': 'Shoes', 'City': 'Mumbai'},
        ]

df = pd.DataFrame(test_data)
df

Output:

    Product City
0   product1    city1
1   product2    city2
2   Dress   city3
3   Dress   Mumbai
4   product3    city2
5   Shoes   city2
6   Shoes   Mumbai

Filtering script:

releavnt_product = ['Dress', 'Shoes']
df.query('(Product in @releavnt_product) and (City == "Mumbai")')

Output:

    Product City
3   Dress   Mumbai
6   Shoes   Mumbai

Answered By: Ilan Geffen

Answer 3

With the requirement that len(list1) == len(list2) + 1 then you can have a function to combine them and then join

def combine(lst1, lst2):
    it = iter(lst1)
    yield next(it)
    for item in lst2:
        yield item
        yield next(it)

list1 = ['Product == "Dress"', 'Product == "Shoes"', 'City == "Mumbai"']
list2 = ['|', '&']
res = ' '.join(combine(list1, list2))

Answered By: Steven Summers

Answer 4

Here’s a variation on the answer from @rudolfovic that doesn’t involve removing redundant characters.

The assumption here is that list1 is of length N and that of list2 is N-1 (as stated by OP) and N > 0

list1 = ['Product == "Dress"', 'Product == "Shoes"', 'City == "Mumbai"']
list2 = ['|', '&']

new_list = list1[0] + ''.join(f' {a} {b}' for a, b in zip(list2, list1[1:]))

print(new_list)

Output:

Product == "Dress" | Product == "Shoes" & City == "Mumbai"

Answered By: DarkKnight

Create one long string from multiple lists of strings

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