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Python – Sum elements matching condition
• Last Updated : 29 Dec, 2019

Checking a number/element by a condition is a common problem one faces and is done in almost every program. Sometimes we also require to get the totals sum that match the particular condition to have a distinguish which to not match for further utilization. Lets discuss certain ways in which this task can be achieved.

Method #1 : Using loop
This is brute force method to perform this particular task. In this, we iterate list, find elements that match a particular condition and take sum.

 `# Python 3 code to demonstrate ``# Sum elements matching condition``# using loop`` ` `# initializing list``test_list ``=` `[``3``, ``5``, ``1``, ``6``, ``7``, ``9``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# using loop``# Sum elements matching condition``# checks for odd``res ``=` `0``for` `ele ``in` `test_list:``    ``if` `ele ``%` `2` `!``=` `0``:``        ``res ``=` `res ``+` `ele ``         ` `# printing result``print` `(``"The sum of odd elements: "` `+` `str``(res))`
Output :
```The original list is : [3, 5, 1, 6, 7, 9]
The sum of odd elements: 25
```

Method #2 : Using `sum() + generator expression`
This method uses the trick of adding elelement to the sum whenever the generator expression returns true. By the time list gets exhausted, summation of numbers matching a condition is returned.

 `# Python 3 code to demonstrate ``# Sum elements matching condition``# using sum() + generator expression`` ` `# initializing list``test_list ``=` `[``3``, ``5``, ``1``, ``6``, ``7``, ``9``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# using sum() + generator expression``# Sum elements matching condition``# checks for odd``res ``=` `sum``(i ``for` `i ``in` `test_list ``if` `i ``%` `2` `!``=` `0``)`` ` `# printing result``print` `(``"The sum of odd elements: "` `+` `str``(res))`
Output :
```The original list is : [3, 5, 1, 6, 7, 9]
The sum of odd elements: 25
```

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