In [82]: d Out[82]: A B C D 0 John Doe 45 True False 1 Jane Smith 32 False False 2 Alan Holmes 55 False True 3 Eric Lamar 29 True True Solution 1: In [83]: d.loc[d.C | d.D] Out[83]: A B C D 0 John Doe 45 True False 2 Alan Holmes 55 False … Read more
In C++ the bit representation (and even the size) of a bool is implementation defined; generally it’s implemented as a char-sized type taking 1 or 0 as possible values. If you set its value to anything different from the allowed ones (in this specific case by aliasing a bool through a char and modifying its … Read more
Yes* Yes, usually (and in your case) it does break out of the loop and returns from the method. An Exception One exception is that if there is a finally block inside the loop and surrounding the return statement then the code in the finally block will be executed before the method returns. The finally … Read more
In the following cases: test = False test = “” test = 0 test = 0.0 test = [] test = () test = {} test = set() the if test will differ: if test: #False if test is not None: #True This is the case because is tests for identity, meaning test is not … Read more
You probably want something like this: >>> a = np.array([True, True, True, False, False]) >>> b = np.array([[1,2,3,4,5], [1,2,3,4,5]]) >>> b[:,a] array([[1, 2, 3], [1, 2, 3]]) Note that for this kind of indexing to work, it needs to be an ndarray, like you were using, not a list, or it’ll interpret the False and … Read more
You probably want something like this: >>> a = np.array([True, True, True, False, False]) >>> b = np.array([[1,2,3,4,5], [1,2,3,4,5]]) >>> b[:,a] array([[1, 2, 3], [1, 2, 3]]) Note that for this kind of indexing to work, it needs to be an ndarray, like you were using, not a list, or it’ll interpret the False and … Read more
not is implemented through the __nonzero__ special method, which is required to return either True or False, so it can’t give the required result. Instead the ~ operator is used, which is implemented through the __not__ special method. For the same reason, & and | are used in place of and and or. PEP 335 … Read more
Rule of thumb: Use -a and -o inside square brackets, && and || outside. It’s important to understand the difference between shell syntax and the syntax of the [ command. && and || are shell operators. They are used to combine the results of two commands. Because they are shell syntax, they have special syntactical … Read more
The problems with the “!!” idiom are that it’s terse, hard to see, easy to mistake for a typo, easy to drop one of the “!’s”, and so forth. I put it in the “look how cute we can be with C/C++” category. Just write bool isNonZero = (integerValue != 0); … be clear.