Add info from one list to another

February 24, 2022

So I have this two list, one with cities and one with lists of other infos. I would like to insert the name of the cities in index 0 of each list of the second list. Problem is at the end I have only one city name that is printed (the last one). Can somebody help me out with this ? Thank you !

cities = ["Paris", "London", "New York"]

data = [
    ["", "", "", "", 1, 1, "Buildings"],
    ["", "", "", "", 2, 1, "Streets"],
    ["", "", "", "", 3, 1, "Avenues"],
    ["", "", "", "", 1, 2, "Buildings"],
    ["", "", "", "", 2, 2, "Streets"],
    ["", "", "", "", 3, 2, "Avenues"],
]

result = []
counter = -1
while counter != len(cities) - 1:
    counter += 1
    number = -1
    while number != len(data) - 1:
        number += 1
        data[number][0] = cities[counter]
        result.append(data[number])

print(result)

gives me

result = [['New York', '', '', '', 1, 1, 'Buildings'], 
['New York', '', '', '', 2, 1, 'Streets'], 
['New York', '', '', '', 3, 1, 'Avenues'], 
['New York', '', '', '', 1, 2, 'Buildings'], 
['New York', '', '', '', 2, 2, 'Streets'], 
['New York', '', '', '', 3, 2, 'Avenues'], 
# (and so on)
]

while I’d rather have

result = [['New York', '', '', '', 1, 1, 'Buildings'], 
['Paris', '', '', '', 2, 1, 'Streets'], 
['Paris', '', '', '', 3, 1, 'Avenues'], 
['Paris', '', '', '', 1, 2, 'Buildings'], 
['Paris', '', '', '', 2, 2, 'Streets'], 
['Paris', '', '', '', 3, 2, 'Avenues'], 
['Paris', '', '', '', 1, 1, 'Buildings'], 
['London', '', '', '', 2, 1, 'Streets'], 
['London', '', '', '', 3, 1, 'Avenues'], 
['London', '', '', '', 1, 2, 'Buildings'], 
['London', '', '', '', 2, 2, 'Streets'], 
['London', '', '', '', 3, 2, 'Avenues'], 
['London', '', '', '', 1, 1, 'Buildings'], 
['New York', '', '', '', 2, 1, 'Streets'], 
['New York', '', '', '', 3, 1, 'Avenues'], 
['New York', '', '', '', 1, 2, 'Buildings'], 
['New York', '', '', '', 2, 2, 'Streets'], 
['New York', '', '', '', 3, 2, 'Avenues']
]

Thank you

>Solution :

Here is some code that can help with your problem:

cities = ["Paris", "London", "New York"]

data = [
    ["", "", "", "", 1, 1, "Buildings"],
    ["", "", "", "", 2, 1, "Streets"],
    ["", "", "", "", 3, 1, "Avenues"],
    ["", "", "", "", 1, 2, "Buildings"],
    ["", "", "", "", 2, 2, "Streets"],
    ["", "", "", "", 3, 2, "Avenues"],
]

result = []
for i in cities:
  for j in data:
    result.append(j.copy()) #adding a copy of the list to result
    result[len(result) - 1][0] = i #editing the list we just added (the now last element in result) so the first element is the city

#printing the result
for i in result:
  print(i)

Output:

['Paris', '', '', '', 1, 1, 'Buildings']
['Paris', '', '', '', 2, 1, 'Streets']
['Paris', '', '', '', 3, 1, 'Avenues']
['Paris', '', '', '', 1, 2, 'Buildings']
['Paris', '', '', '', 2, 2, 'Streets']
['Paris', '', '', '', 3, 2, 'Avenues']
['London', '', '', '', 1, 1, 'Buildings']
['London', '', '', '', 2, 1, 'Streets']
['London', '', '', '', 3, 1, 'Avenues']
['London', '', '', '', 1, 2, 'Buildings']
['London', '', '', '', 2, 2, 'Streets']
['London', '', '', '', 3, 2, 'Avenues']
['New York', '', '', '', 1, 1, 'Buildings']
['New York', '', '', '', 2, 1, 'Streets']
['New York', '', '', '', 3, 1, 'Avenues']
['New York', '', '', '', 1, 2, 'Buildings']
['New York', '', '', '', 2, 2, 'Streets']
['New York', '', '', '', 3, 2, 'Avenues']

The way this code works is that:

For every city in the list cities, we first add a copy of every list inside of data to result and then change the value of the first element to the city.

I hope this helped! Let me know if you need any further help or clarification 🙂