["python","tuples"]
How to create a "singleton" tuple with only one element

In the below example, I would expect all the elements to be tuples. Why is a tuple converted to a string when it only contains a single string? >>> a = [('a'), ('b'), ('c', 'd')] >>> a ['a', 'b', ('c', 'd')] >>> >>> for elem in a: ... print type(elem) ... <type 'str'> <type 'str'> <type 'tuple'>
why is a tuple converted to a string when it only contains a single string? a = [('a'), ('b'), ('c', 'd')] Because those first two elements aren't tuples; they're just strings. The parenthesis don't automatically make them tuples. You have to add a comma after the string to indicate to python that it should be a tuple. >>> type( ('a') ) <type 'str'> >>> type( ('a',) ) <type 'tuple'> To fix your example code, add commas here: >>> a = [('a',), ('b',), ('c', 'd')] ^ ^ From the Python Docs: A special problem is the construction of tuples containing 0 or 1 items: the syntax has some extra quirks to accommodate these. Empty tuples are constructed by an empty pair of parentheses; a tuple with one item is constructed by following a value with a comma (it is not sufficient to enclose a single value in parentheses). Ugly, but effective. If you truly hate the trailing comma syntax, a workaround is to pass a list to the tuple() function: x = tuple(['a'])