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NOTE: I edited the question!

I am having trouble with iteration in Python, especially when I would like to sum up values up to a certain number. Here's more information on the problem I'm facing:

I have a list of tuples that looks like this:

[(1, 0.5, 'min'),
 (2, 3, 'NA'),
 (3, 6, 'NA'),
 (4, 40, 'NA'),
 (5, 90, 'NA'),
 (6, 130.8, 'max'),
 (7, 129, 'NA'),
 (8, 111, 'NA'),
 (9, 8, 'NA'),
 (10, 9, 'NA'),
 (11, 0.01, 'min'),
 (12, 9, 'NA'),
 (13, 40, 'NA'),
 (14, 90, 'NA'),
 (15, 130.1, 'max'),
 (16, 112, 'NA'),
 (17, 108, 'NA'),
 (18, 90, 'NA'),
 (19, 77, 'NA'),
 (20, 68, 'NA'),
 (21, 0.9, 'min'),
 (22, 8, 'NA'),
 (23, 40, 'NA'),
 (24, 90, 'NA'),
 (25, 92, 'NA'),
 (26, 130.4, 'max')]

I want to sum each value leading up to "max" and each value leading up to "min" and append these results to two separate lists.

For instance, the output should be:

min_sums = [1+2+3+4+5,11+12+13+14, 21+22+23+24+15]
max_sums = [6+7+8+9+10, 15+16+17+18+19+20, 26]

I would also like to keep track of the values I am actually summing up and have this as an output as well:

min_sums_lst = [[1,2,3,4,5], [11,12,13,14],[21,22,23,24,15]]
max_sums_lst = [[6,7,8,9,10], [15,16,17,18,19,20], [26]]

I'm thinking I can use the index value, but am pretty new to Python and am not exactly sure how to proceed. I'm studying biology, but I believe learning CS could help with my work.

max_list = []
min_list = []
flag = ''
min_index = 0
max_index = float('inf');

if flag == 'h':
    max_list.append(item)
elif flag == 'c':
    min_list.append(item)

for i, item in enumerate(minmax_list):
    print(i, item)
    print("max_index: ", max_index)
    print("min_index: ", min_index)
    if item[2] == 'min':
         min_index = i
         max_list('h', item[0])
    elif item[2] == 'NA' and (i < max_index):
        max_list('h', item[0])
    elif item[2] == 'max':
         max_index = i
         max_list('c', item[0])
    elif item[2] == 'NA' and (i > min_index):
        min_list('c', item[0])

I'm quite new to Python - any help would be appreciated. I am only trying to add the first item in each tuple based on min and max as indicated in the output above.

djennacs
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  • I'm still having problems with how to keep track of values I am actually summing up, so if anyone can add on about how to obtain min_sums_lst and max_sums_lst, it would help a lot! – djennacs Oct 22 '17 at 00:43

2 Answers2

1

Sorry, didn't bother reading your attempt, looks very complicated.

min_sums = []
max_sums = []
for x, _, what in minmax_list:
    if what != 'NA':
        current = min_sums if what == 'min' else max_sums
        current.append(0)
    current[-1] += x
Stefan Pochmann
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  • thank you for the answer - it seems correct, but I'm trying to expand it and make more sense of your strategy! – djennacs Oct 21 '17 at 23:54
1

My answer takes a slightly different approach to @Stefan's. It does a bit more validation, and you could pretty easily add other kinds besides 'min' and 'max'.

def partition_items(items):
    lists = {
        'min': [],
        'max': [],
    }
    current_kind = None
    current_list = None
    for value, _, kind in items:
        if kind != current_kind and kind != 'NA':
            current_kind = kind
            # You'll get a error here if current_kind isn't one of 'min'
            # or 'max'.
            current_list = lists[current_kind]
            current_list.append(0)
        # You'll get an error here if the first item in the list doesn't
        # have type of 'min' or 'max'.
        current_list[-1] += value
    return lists


lists = partition_items(items)
print(lists['min'])
# -> [15, 50, 115]
print(lists['max'])
# -> [40, 105, 26]