CODEWITHSUNDEEP
pythonpython-3.xsumtuples
user3008918
user3008918

Reputation: 105

Sum item inside a tuple

I have a list of nested tuples in which the second element is na float:

l = [('drink', ['vodka', '9.2', 'beer', '6.3', 'alcohol', '5.4', 'gin', '2.1', 'liquid']), 
('evict', ['tenant', '66.0', 'squatter', '2.75', 'owner', '1.1', 'bum', '1.0', 'deadbeat', '1.0'])]

I want to sum the three first items on the list, and append the result to the beginning, like this:

l = [('drink', 20.9 ['vodka', '9.2', 'beer', '6.3', 'alcohol', '5.4', 'gin', '2.1']), 
('evict', 69.75 ['tenant', '66.0', 'squatter', '2.75', 'bum', '1.0', 'deadbeat', '1.0'])]

I am using the code below:

sorted_by_sum=[]
for t in l:
    tup=[t[0]]
    tup.append(t[1])
    tup.append(sum(float(x) for x in t[0][1:6:2]))
    sorted_by_sum.append(tuple(tup))

But I am getting the mistake:

ValueError: could not convert string to float: 'a'

Any hints on what how to correct this? I thank you very much in advance.

Upvotes: 0

Views: 940

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1124798

You want to access the second element of the tuple to sum; not t[0] (the string):

tup.append(sum(float(x) for x in t[1][1:6:2]))

but make that the first .append() statement, not the second.

You can turn the whole loop into a list comprehension, using tuple unpacking to give easier to follow names to the two elements of each tuple:

sorted_by_sum = [(name, sum(float(x) for x in items[1:6:2]), items) 
                 for name, items in l]

Demo:

>>> l = [('drink', ['vodka', '9.2', 'beer', '6.3', 'alcohol', '5.4', 'gin', '2.1', 'liquid']), 
... ('evict', ['tenant', '66.0', 'squatter', '2.75', 'owner', '1.1', 'bum', '1.0', 'deadbeat', '1.0'])]
>>> [(name, sum(float(x) for x in items[1:6:2]), items) for name, items in l]
[('drink', 20.9, ['vodka', '9.2', 'beer', '6.3', 'alcohol', '5.4', 'gin', '2.1', 'liquid']), ('evict', 69.85, ['tenant', '66.0', 'squatter', '2.75', 'owner', '1.1', 'bum', '1.0', 'deadbeat', '1.0'])]

Upvotes: 3

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