CODEWITHSUNDEEP
pythonlist
M_F
M_F

Reputation: 11

Loop through list of lists in Python and sum up all index 1, then all index 2 etc

Been trying to figure out a way to sum up each and every index in a list of lists in Python. For example a list of list like this:

carbon_dioxide = ([" ", "1990", "1991", "1992"], ["factories", "100", "101", "102"], ["food industry", "50", "51", "52"], ["transports", "25", "26", "27"])

I want to exclude the first list and then sum up index 1 in list 2 ("100") with index 1 in list 3 ("50") and 4 ("25").

Then i want the iteration to continue and sum up index 2 in all the lists.

I do not want to import any modules, just pure code since I am a beginner trying to grasp the basics. I tried different solutions but no. For example this one, but it gave me the whole list of lists except from list[0]:

for i in range(1, len(carbon_dioxide)):
    print(carbon_dioxide[i])

Do you have any ideas? Thanks!

Upvotes: 1

Views: 173

Answers (3)

gold_cy
gold_cy

Reputation: 14216

It sounds like you want to add carbon dioxide levels for each year if I am not mistaken. A more digest-able output might be a dictionary where you have a year to (sum of carbon dioxide levels) mapping.

year_nums = zip(*(c[1:] for c in carbon_dioxide))  # gives us a year and all the CO2 levels

output = {yn[0]: sum(map(int, yn[1:])) for yn in year_nums}

print(output)
>> {'1990': 175, '1991': 178, '1992': 181}

Upvotes: 1

DarrylG
DarrylG

Reputation: 17156

Adding to your start.

results = [0]*(len(carbon_dioxide[0])-1)     # Initialize array for results
                                             # with all zeros
for sublist in carbon_dioxide[1:]:           # skips 1st sublist in crbon_dioxide
    for index, v in enumerate(sublist[1:]):  # skips first item in each sublist 
                                             # i.e. skips "", "factories", etc.
        results[index] += int(v)             # Add to result at index 'index'
        
print(results)  # [175, 178, 181]

​

Upvotes: 0

Synthaze
Synthaze

Reputation: 6090

I am not sure that is what you're looking for, still:

carbon_dioxide = ([" ", "1990", "1991", "1992"], ["factories", "100", "101", "102"], ["food industry", "50", "51", "52"], ["transports", "25", "26", "27"])

for k in range(1,4):
    for i in range(1, len(carbon_dioxide)):
        for j in range(i+1,len(carbon_dioxide)):
            carbon_dioxide[i][k] = int(carbon_dioxide[i][k]) + int(carbon_dioxide[j][k])
    print(carbon_dioxide)

Output:

([' ', '1990', '1991', '1992'], ['factories', 175, '101', '102'], ['food industry', 75, '51', '52'], ['transports', '25', '26', '27'])
([' ', '1990', '1991', '1992'], ['factories', 175, 178, '102'], ['food industry', 75, 77, '52'], ['transports', '25', '26', '27'])
([' ', '1990', '1991', '1992'], ['factories', 175, 178, 181], ['food industry', 75, 77, 79], ['transports', '25', '26', '27'])

Upvotes: 0

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