这应该很简单 几乎和它一样有效 （要获得更有效的解决方案，请检查Ashwini
Chaudharys答案，以及最有效的检查jamylaks答案和评论）：

result = None
# Go trough one array
for i in x:

    # The element repeats in the other list...
    if i in y:

        # Store the result and break the loop
        result = i
        break

或者更优雅的事件是封装相同的功能以使用PEP
8进行工作，例如编码样式约定：

def get_first_common_element(x,y):
    ''' Fetches first element from x that is common for both lists
        or return None if no such an element is found.
    '''
    for i in x:
        if i in y:
            return i

    # In case no common element found, you could trigger Exception
    # Or if no common element is _valid_ and common state of your application
    # you could simply return None and test return value
    # raise Exception('No common element found')
    return None

而且，如果您需要所有通用元素，可以像这样简单地进行操作：

>>> [i for i in x if i in y]
[1, 2, 3]