That’s an excellent question. The key insight is that tuples have no way of knowing whether the objects inside them are mutable. The only thing that makes an object mutable is to have a method that alters its data. In general, there is no way to detect this. Another insight is that Python’s containers don’t … Read more
Summary Tuples tend to perform better than lists in almost every category: 1) Tuples can be constant folded. 2) Tuples can be reused instead of copied. 3) Tuples are compact and don’t over-allocate. 4) Tuples directly reference their elements. Tuples can be constant folded Tuples of constants can be precomputed by Python’s peephole optimizer or … Read more
I don’t think there is a general purpose tuple class in Java but a custom one might be as easy as the following: public class Tuple<X, Y> { public final X x; public final Y y; public Tuple(X x, Y y) { this.x = x; this.y = y; } } Of course, there are some … Read more
n = 1 # N. . . [x[n] for x in elements]
ax.plot() returns a tuple with one element. By adding the comma to the assignment target list, you ask Python to unpack the return value and assign it to each variable named to the left in turn. Most often, you see this being applied for functions with more than one return value: base, ext = os.path.splitext(filename) … Read more
You can use a generator expression: tuple(i for i in (1, 2, 3)) but parentheses were already taken for … generator expressions.
You could google “tuple unpacking”. This can be used in various places in Python. The simplest is in assignment: >>> x = (1,2) >>> a, b = x >>> a 1 >>> b 2 In a for-loop it works similarly. If each element of the iterable is a tuple, then you can specify two variables, … Read more
Python separates the right-hand side expression from the left-hand side assignment. First the right-hand side is evaluated, and the result is stored on the stack, and then the left-hand side names are assigned using opcodes that take values from the stack again. For tuple assignments with 2 or 3 items, Python just uses the stack … Read more
myfun(*some_tuple) does exactly what you request. The * operator simply unpacks the tuple (or any iterable) and passes them as the positional arguments to the function. Read more about unpacking arguments.
It is the commas, not the parentheses, which are significant. The Python tutorial says: A tuple consists of a number of values separated by commas Parentheses are used for disambiguation in other places where commas are used, for example, enabling you to nest or enter a tuple as part of an argument list. See the … Read more