r is a numpy (rec)array. So r[“dt”] >= startdate is also a (boolean) array. For numpy arrays the & operation returns the elementwise-and of the two boolean arrays. The NumPy developers felt there was no one commonly understood way to evaluate an array in boolean context: it could mean True if any element is True, … Read more
The % (modulo) operator yields the remainder from the division of the first argument by the second. The numeric arguments are first converted to a common type. A zero right argument raises the ZeroDivisionError exception. The arguments may be floating point numbers, e.g., 3.14%0.7 equals 0.34 (since 3.14 equals 4*0.7 + 0.34.) The modulo operator … Read more
Here is some list functions based on Martin v. Löwis’s representation: where w = sys.stdout.write Although doubly linked lists are famously used in Raymond Hettinger’s ordered set recipe, singly linked lists have no practical value in Python. I’ve never used a singly linked list in Python for any problem except educational. Thomas Watnedal suggested a … Read more
The current answers are good, but do not talk about how they are just syntactic sugar to some pattern that we are so used to. Let’s start with an example, say we have 10 numbers, and we want a subset of those that are greater than, say, 5. For the above task, the below approaches … Read more
item is most likely a string in your code; the string indices are the ones in the square brackets, e.g., gravatar_id. So I’d first check your data variable to see what you received there; I guess that data is a list of strings (or at least a list containing at least one string) while it … Read more
How about: This is extended slice syntax. It works by doing [begin:end:step] – by leaving begin and end off and specifying a step of -1, it reverses a string.
You’re trying to delete an open file, and the docs for os.remove() state… On Windows, attempting to remove a file that is in use causes an exception to be raised You could change the code to… …or you can replace all that with… …which will truncate the file to zero length before opening.
As the error message indicates, you have an indentation error. It is probably caused by a mix of tabs and spaces.
2230 Links to the documentation: int() str() Conversion to a string is done with the builtin str() function, which basically calls the __str__() method of its parameter.
The len() function can be used with several different types in Python – both built-in types and library types. For example: