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Jun 16, 2012 · There are two operators in Python for the "not equal" condition - a.) != If values of the two operands are not equal, then the condition becomes true. (a != b) is true. b.) <> If values of the two operands are not equal, then the condition becomes true. (a <> b) is true. This is similar to the != operator.
Python checks whether the object you're referring to has the same memory address as the global None object - a very, very fast comparison of two numbers. By comparing equality, Python has to look up whether your object has an __eq__ method. If it does not, it examines each superclass looking for an __eq__ method. If it finds one, Python calls it.
May 14, 2012 · Method: (A==B).all(), 0.03031857 Method: np.array_equal(A,B), 0.030025185 Method: np.array_equiv(A,B), 0.030141515 According to the results above, the numpy methods seem to be faster than the combination of the == operator and the all() method and by comparing the numpy methods the fastest one seems to be the numpy.array_equal method.
For example, the intention of your example is probably to check whether x has a value equal to 2 (==), not whether x is literally referring to the same object as 2. Something else to note: because of the way the CPython reference implementation works, you'll get unexpected and inconsistent results if you mistakenly use is to compare for reference equality on integers:
Oct 19, 2010 · As for why the val != None is not recommended: If val can be either None or a more complex thing, like a numpy array, it's not entirely clear whether this intends to be an element-wise comparison (e.g: arr>0 will produce a list of indices at which elements of arr are positive), so if you expect val to be either an array or None, then arr is None is the safest way to test this.
Jun 16, 2016 · That is: I want to do something when a is not negative. I know that I can write if a != 0: to check whether a is not equal to 0. So, I tried using if a !< 0:, following similar logic. However, this is apparently not supported: >>> if a !< 0: File "<stdin>", line 1 if a !< 0: ^ SyntaxError: invalid syntax Why is this syntax invalid?
Jun 3, 2009 · This answer is awful; it relies on nan being the only thing in the universe not equal to itself. AT THE VERY LEAST it should be return isinstance(num, float) and num != num . The overhead of verifying the type is better than the possibility of actually being wrong, which this can be.
The operators is and is not test for object identity: x is y is true if and only if x and y are the same object. x is not y yields the inverse truth value. Share Improve this answer
Sep 21, 2017 · I have a .txt file with multiple strings, seperated by a '-'. I used a split to seperate some of the strings into variables, and 2 of them are equal, but in an if statement they come out as not equal.
Nov 25, 2023 · It is x that has the value, so we want to know if x is equal to 4; we don't want to tell Python that it is. In that case, you need double =: >>> x = 4 >>> print x == 4 True In any place that you can use =, you can use ==; but it will have a different meaning. For example: >>> x = 4 >>> print x 4 >>> x == 4 True x = 4 tells Python that x is ...
