You are trying to run a Python 2 codebase with Python 3. xrange() was renamed to range() in Python 3. Run the game with Python 2 instead. Don’t try to port it unless you know what you are doing, most likely there will be more problems beyond xrange() vs. range(). For the record, what you … Read more
Because it’s more common to call range(0, 10) which returns [0,1,2,3,4,5,6,7,8,9] which contains 10 elements which equals len(range(0, 10)). Remember that programmers prefer 0-based indexing. Also, consider the following common code snippet: for i in range(len(li)): pass Could you see that if range() went up to exactly len(li) that this would be problematic? The programmer … Read more
For performance, especially when you’re iterating over a large range, xrange() is usually better. However, there are still a few cases why you might prefer range(): In python 3, range() does what xrange() used to do and xrange() does not exist. If you want to write code that will run on both Python 2 and … Read more
All of the following examples use var str = “Hello, playground” Swift 4 Strings got a pretty big overhaul in Swift 4. When you get some substring from a String now, you get a Substring type back rather than a String. Why is this? Strings are value types in Swift. That means if you use … Read more
use reversed() function: reversed(range(10)) It’s much more meaningful. Update: If you want it to be a list (as btk pointed out): list(reversed(range(10))) Update: If you want to use only range to achieve the same result, you can use all its parameters. range(start, stop, step) For example, to generate a list [5,4,3,2,1,0], you can use the … Read more
In Python 2.x: range creates a list, so if you do range(1, 10000000) it creates a list in memory with 9999999 elements. xrange is a sequence object that evaluates lazily. In Python 3: range does the equivalent of Python 2’s xrange. To get the list, you have to explicitly use list(range(…)). xrange no longer exists.
Rather than using a decimal step directly, it’s much safer to express this in terms of how many points you want. Otherwise, floating-point rounding error is likely to give you a wrong result. Use the linspace function from the NumPy library (which isn’t part of the standard library but is relatively easy to obtain). linspace … Read more
NSString *string = @”hello bla bla”; if ([string rangeOfString:@”bla”].location == NSNotFound) { NSLog(@”string does not contain bla”); } else { NSLog(@”string contains bla!”); } The key is noticing that rangeOfString: returns an NSRange struct, and the documentation says that it returns the struct {NSNotFound, 0} if the “haystack” does not contain the “needle”. And if … Read more
In ES6 using Array from() and keys() methods. Array.from(Array(10).keys()) //=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] Shorter version using spread operator. […Array(10).keys()] //=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] Start from 1 by passing map function to Array from(), with an object with a length property: Array.from({length: … Read more
The Python 3 range() object doesn’t produce numbers immediately; it is a smart sequence object that produces numbers on demand. All it contains is your start, stop and step values, then as you iterate over the object the next integer is calculated each iteration. The object also implements the object.__contains__ hook, and calculates if your … Read more