iterable

(Using Python 3.1) I know this question has been asked many times for the general question of testing if iterator is empty; obviously, there's no neat solution to that (I guess for a reason - an iterator doesn't really know if it's empty until it's asked to return its next value). I have a specific example, however, and was hoping I can make clean and Pythonic code out of it: #lst is an arbitrary iterable #f must return the smallest non-zero element, or return None if empty def f(lst): flt = filter(lambda x : x is not None and x != 0, lst) if # somehow check that flt is empty return None

I recently started playing with Scala and ran across the following. Below are 4 different ways to iterate through the lines of a file, do some stuff, and write the result to another file. Some of these methods work as I would think (though using a lot of memory to do so) and some eat memory to no end. The idea was to wrap Scala's getLines Iterator as an Iterable. I don't care if it reads the file multiple times - that's what I expect it to do. Here's my repro code: class FileIterable(file: java.io.File) extends Iterable[String] { override def iterator = io.Source.fromFile(file).getLines } //

I have a class in python, which has an iterable as instance variable. I want to iterate the instances of the class by iterating over the embedded iterable. I implemented this as follows: def __iter__(self): return self._iterable.__iter__() I don't really feel that comfortable calling the __iter__() method on the iterable, as it is a special method. Is this how you would solve this problem in python or is there a more elegant solution? The "best" way to way to delegate __iter__ would be: def __iter__(self): return iter(self._iterable) Alternately, it might be worth knowing about: def __iter__

So I am implementing a mapreduce job which means I am dealing with key value pairs. I have the variable Iterable<FreqDataWritable> values FreqDataWritable is an object that contains pieces of information, but for now I am only concerned with one piece of information it holds which is a String which is accessed by getFilename(). I have the following loop: ArrayList<String> filenames = new ArrayList<String>(); for(FreqDataWritable i : values) { filenames.add(i.getFilename()); } Now all I want to do is print the values in the array list filenames. for(int i = 0; i < filenames.size(); i++) {

I've got the following wrapper for a dictionary: class MyDict: def __init__(self): self.container = {} def __setitem__(self, key, value): self.container[key] = value def __getitem__(self, key): return self.container[key] def __iter__(self): return self def next(self): pass dic = MyDict() dic['a'] = 1 dic['b'] = 2 for key in dic: print key My problem is that I don't know how to implement the next method to make MyDict iterable. Any advice would be appreciated. Dictionaries are themselves not an iterator (which can only be iterated over once ). You usually make them an iterable , an object for

What's the easiest/fastest way to convert an Iterable<Character> to a String of the characters from the Iterable? For example, how to convert an Iterable of "A" , "B" , and "C" , to a String "ABC" ? The iter.toString() returns a String "[A, B, C]" . 5 Versions: 1) Java 8 streams collecting via StringBuilder.append() : public static String streamAppend(Iterable<Character> chars){ return StreamSupport.stream(chars.spliterator(), true) .collect( StringBuilder::new, StringBuilder::append, StringBuilder::append ) .toString(); } Java 8 Streams collecting via Collectors.joining() public static String

Suppose I have a class Point and a function to process Point instances class Point { private final int x, y; ... } ... void handlePoints(Iterable<Point> points) { for (Point p: points) {...} } Now I would like to read points from a file. Each line of the file contains two numbers, so I have a function ("factory method") to create a point from a line. Point makePoint(String line) { ... } What should I do now? I can write a function to read the file to a list of points and call the handlePoints function. List<Point> readPoints(BufferedReader reader) {...} // use makePoint here void handlePoints