Re: basic questions on cmp, and sort
Schüle Daniel wrote: first question In [117]: cmp(ABC,['A','B','C']) Out[117]: 1 against what part of the list is the string ABC compared? http://docs.python.org/lib/comparisons.html Objects of different types, except different numeric types and different string types, never compare equal; such objects are ordered consistently but arbitrarily (so that sorting a hetero- geneous array yields a consistent result) class X does not implement and cmp what is this comparision is based on? objects of the same types that don't support proper comparison are ordered by their address third question sort([[1,2,3],[ABC],['Z','A'], X(), 4) how does python handle heterogenous items in the list in this case? Objects of different types, except different numeric types and different string types, never compare equal; such objects are ordered consistently but arbitrarily (so that sorting a hetero- geneous array yields a consistent result) first I assumed no, first you assumed that this wasn't documented. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: basic questions on cmp, and sort
Ben Finney [EMAIL PROTECTED] wrote: To: python-list@python.org Sent: Thursday, October 26, 2006 4:44 AM Subject: Re: basic questions on cmp, and sort Schüle Daniel [EMAIL PROTECTED] writes: 8--- third question sort([[1,2,3],[ABC],['Z','A'], X(), 4) sort([[1,2,3],[ABC],['Z','A'], X(), 4) File stdin, line 1 sort([[1,2,3],[ABC],['Z','A'], X(), 4) ^ SyntaxError: invalid syntax needs a closing ']' to make the list a list. - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
basic questions on cmp, and sort
Hello, first question In [117]: cmp(ABC,['A','B','C']) Out[117]: 1 against what part of the list is the string ABC compared? second question In [119]: class X(object): .: pass .: In [120]: X() X() Out[120]: True In [121]: X() X() Out[121]: False In [122]: X() X() Out[122]: True In [123]: X() X() Out[123]: True In [124]: X() X() Out[124]: False class X does not implement and cmp what is this comparision is based on? third question sort([[1,2,3],[ABC],['Z','A'], X(), 4) how does python handle heterogenous items in the list in this case? first I assumed that cmp function used in sort is based on len, when the items are sequences, but this is wrong Regards, Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: basic questions on cmp, and sort
Schüle Daniel [EMAIL PROTECTED] writes: Hello, first question In [117]: cmp(ABC,['A','B','C']) Out[117]: 1 against what part of the list is the string ABC compared? Why part? There are two objects; they are compared to each other. How this comparison is implemented is a matter handled by the class of each object. second question In [119]: class X(object): .: pass .: In [120]: X() X() [... differing results ...] class X does not implement and cmp what is this comparision is based on? Classes can implement various functions to allow comparisons to work: URL:http://docs.python.org/ref/customization.html#l2h-187 In the absence of those, the comparison's result is (I believe) implementation-dependent -- which means, don't rely on any particular behaviour. third question sort([[1,2,3],[ABC],['Z','A'], X(), 4) sort([[1,2,3],[ABC],['Z','A'], X(), 4) File stdin, line 1 sort([[1,2,3],[ABC],['Z','A'], X(), 4) ^ SyntaxError: invalid syntax Care to give an actual example? -- \I went to the hardware store and bought some used paint. It | `\ was in the shape of a house. -- Steven Wright | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: basic questions on cmp, and sort
Schüle Daniel schrieb: first question In [117]: cmp(ABC,['A','B','C']) Out[117]: 1 against what part of the list is the string ABC compared? The names of the types are compared: py cmp(string, list) 1 second question In [119]: class X(object): .: pass .: In [120]: X() X() Out[120]: True what is this comparision is based on? The addresses of the objects, in main memory. third question sort([[1,2,3],[ABC],['Z','A'], X(), 4) how does python handle heterogenous items in the list in this case? pair-by-pair. It is quite difficult to impose a total order on all objects; this will go away in Python 3. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
