2009/7/5 Steven Buck <bucks...@gmail.com>: >>>> for i in len(test): > testvar2.append(test[i][2]) > > I want testvar2 = [2,5,8] but instead I get the following error message: > > Traceback (most recent call last): > File "<pyshell#34>", line 1, in <module> > for i in len(test): > TypeError: 'int' object is not iterable > > Any insight would be appreciated. > Thanks > Steve > -- > Steven Buck > Ph.D. Student > Department of Agricultural and Resource Economics > University of California, Berkeley
This sounds like a homework assignment, and we're not supposed to give out answers to homework. The error message and the docs explain what you're doing wrong if you take a moment to look. from http://www.python.org/doc/2.6/reference/compound_stmts.html#for """for_stmt ::= "for" target_list "in" expression_list ":" suite ["else" ":" suite] The expression list is evaluated once; it should yield an iterable object. An iterator is created for the result of the expression_list. The suite is then executed once for each item provided by the iterator, in the order of ascending indices. Each item in turn is assigned to the target list using the standard rules for assignments, and then the suite is executed.""" As Luke said, len returns an int, which as your error tells you, is not iterable. From the same page: """The for statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable object:""" Therefore you have an iterable, there is no need to try and construct a new one. Does that help? It is extremly unpythonic to iterate over range(len(...)), as it adds in the overhead of two function calls, and ruins the readability of code. The latter is probably the most important of the two. An even more pythonic way to do this would be a list comprehension, http://www.python.org/doc/2.6/tutorial/datastructures.html#list-comprehensions If it's not homework, let us know, and we'll be more than willing to give you code if you still need it. -- Richard "Roadie Rich" Lovely, part of the JNP|UK Famile www.theJNP.com _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
