I have a list name:
my_list = [1,2,3,4,5,6]
I want to output to look like this, 1, 3(1+2),6(1+2+3), 10(1+2+3+4), ...
how can I do this in python? Thank for reply in advance
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jamylak
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user1407199
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for i in range(0,len(list)): old_a=a old_b =b a=old_b b=old_a+old_b print a,b – user1407199 Apr 06 '13 at 09:49
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I tried like this but i am getting sum of the last two elements of list. can we define any function for this and call that function. – user1407199 Apr 06 '13 at 09:50
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Do you actually need the brackets in your output? – jamylak Apr 06 '13 at 10:02
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See also http://stackoverflow.com/q/14423794/989121 – georg Apr 06 '13 at 10:19
3 Answers
2
In Python 3.2+ it's as simple as this:
>>> from itertools import accumulate
>>> nums = [1,2,3,4,5,6]
>>> list(accumulate(nums))
[1, 3, 6, 10, 15, 21]
jamylak
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total = 0
for i, element in enumerate(my_list):
total += element
print "%d (%s)" % (total, '+'.join(my_list[:i+1])
John Szakmeister
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This was assuming you wanted the '(1+2)' in the actual output. Otherwise, I'd go with @jamylak's answer. – John Szakmeister Apr 06 '13 at 09:53
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My answer only works on 3.2+, I misinterpreted the question but this is probably what OP actually wants – jamylak Apr 06 '13 at 10:01
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@user1407199 I'm not exactly sure what OP wants now but either way OP should be covered – jamylak Apr 06 '13 at 10:14
1
Try this one-liner:
b = [sum(a[:i+1]) for i, x in enumerate(a)]
This is not super-efficient (and that's an understatement), because you are summing again and again the entire elements...
for a more efficient solution you can do something like this:
result = []
for i, current in enumerate(a):
if result:
last = result[i - 1]
else:
last = 0
result.append(last + current)
print(result)
>> [1, 3, 6, 10, 15, 21]
zenpoy
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