Python: Move specific lists within list, based on an element, at the end-CodePudding

I have a list which contains other lists. Each element of this list contains 5 elements, like so:

requests = [['abc', 'def', '[email protected]', 'GROUP1', '000'],
           ['ghi', 'jkl', 'ghi,[email protected]', 'GROUP4', '111'],
           ['mno', 'pqr', '[email protected]', 'GROUP4', '222'],
           ['stu', 'vxy', '[email protected]', 'GROUP2', '333'],
           ['123', '456', '[email protected]', 'GROUP4', '444'],
           ['A12', 'B34', '[email protected]', 'GROUP3', '555']]

I would like to sort this list, in such a way that each list that contains an element equal to GROUP4, will be placed at the end of the list. So, the output would look like this:

requests = [['abc', 'def', '[email protected]', 'GROUP1', '000'],
           ['stu', 'vxy', '[email protected]', 'GROUP2', '333'],
           ['A12', 'B34', '[email protected]', 'GROUP3', '555'],
           ['ghi', 'jkl', 'ghi,[email protected]', 'GROUP4', '111'],
           ['mno', 'pqr', '[email protected]', 'GROUP4', '222'],
           ['123', '456', '[email protected]', 'GROUP4', '444'],]

I managed to sort them based on that specific element using:

requests.sort(key=lambda x: x[3])

But this just sorts them alphabetically, based on the 4th element. This won't work if a GROUP5 or GROUP6 is present, as those 2 will be the last elements.

Any ideas on how to do this?

Thank you very much!

CodePudding user response：

You can change the lambda to check if the last character in 'GROUP' is 4

requests.sort(key=lambda x: x[3][-1] == '4')

If you want to sort the rest of the list as well use tuple in the lambda with two conditions

requests.sort(key=lambda x: (x[3][-1] == '4', x[3]))

CodePudding user response：

Move lists with GROUP4 at index [3] to the end by sorting by boolean.

requests.sort(key=lambda el: el[3] == "GROUP4")

CodePudding user response：

you can also use list comprehension:

firstList = [a for a in requests if a[3] != 'GROUP4']
secondList = [a for a in requests if a[3] == 'GROUP4']
firstList.extend(secondList)