Suppose I want to add several numbers together like: 1. Find even numbers between 1-100. 2. Find odd numbers between 2-200. 3. Add them.
So for this, I can check for even numbers and odd numbers respectively, but to add them, they must be stored somewhere. Now how can I do this?
i.e. store the output of the first step, store the output of second step and then add them together.
Find even numbers between 1-100:
>>> l = [i for i in range(1,101) if i % 2 == 0]
>>> print l
[2, 4, 6, ..., 100]
Find odd numbers between 2-200:
>>> l2 = [i for i in range(2,200) if i % 2 != 0]
>>> print l2
[3, 5, 7, ..., 199]
Find the sum:
>>> total = sum(l) + sum(l2)
>>> print total
12540
What I've done is List Comprehensions, a loop which creates values for whatever factors you want. Here's a link to the documentation about it: http://docs.python.org/2/tutorial/datastructures.html#list-comprehensions
% 2 to each candidate: finding the first and then counting in steps of two is (almost) infinitely more efficient.
one = 1 mylist = [] while one != 101: mylist.append(one) one += 1Even Numbers List:
a = [i for i in range(2,101,2)]
Odd Numbers List:
b = [i for i in range(3,200,2)]
Sum:
c = sum(a) + sum(b)
This is what containers like lists are for:
numbers = [] # Setup an empty list
for number in range(10): # Loop over your numbers
numbers.append(number) # Append the number to your list
print sum(numbers) # 45
Results of first and second steps can be stored in 2 different lists.
list1 = [2, 4, 6 .. ]
list2 = [1, 3, 5 .. ]
Lists are documented on python docs at http://docs.python.org/2/tutorial/datastructures.html#more-on-lists
You don't really need a list.
>>> sum(x for x in range(1,100) if x % 2)
2500
>>> sum(x for x in range(2,200) if not x % 2)
9900
list. See your Python tutorial's section about lists.