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Python: fastest way to create a list of n lists

...None, n)] It does not have to create a new int object in every iteration and is about 15 % faster on my machine. Edit: Using NumPy, you can avoid the Python loop using d = numpy.empty((n, 0)).tolist() but this is actually 2.5 times slower than the list comprehension. ...
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Print a list in reverse order with range()?

... may be less intuitive but as the comments mention, this is more efficient and the right usage of range for reversed list. share | improve this answer | follow ...
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Python 3: UnboundLocalError: local variable referenced before assignment [duplicate]

...ather than relying on Globals def function(Var1, Var2): if Var2 == 0 and Var1 > 0: print("Result One") elif Var2 == 1 and Var1 > 0: print("Result Two") elif Var1 < 1: print("Result Three") return Var1 - 1 function(1, 1) ...
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Generating random integer from a range

I need a function which would generate a random integer in given range (including border values). I don't unreasonable quality/randomness requirements, I have four requirements: ...
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Best practices for circular shift (rotate) operations in C++

Left and right shift operators (>) are already available in C++. However, I couldn't find out how I could perform circular shift or rotate operations. ...
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How to append rows to an R data frame

...rs of the type you want for each column, insert values into those vectors, and then, at the end, create your data.frame. Continuing with Julian's f3 (a preallocated data.frame) as the fastest option so far, defined as: # pre-allocate space f3 <- function(n){ df <- data.frame(x = numeric(n)...
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Way to get number of digits in an int?

...thematically, numbers don't have a length, nor do they have digits. Length and digits are both properties of a physical representation of a number in a specific base, i.e. a String. A logarithm-based solution does (some of) the same things the String-based one does internally, and probably does so ...
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How does one make random number between range for arc4random_uniform()?

so my goal in this codebit is to randomly roll two dice and as we all know your regular die only has 6 sides so I imported Foundation for access to arc4random_uniform(UInt32). I attempted using the range of (1..7) to avoid randomly getting 0 however that returned an error which I didn't enjoy too mu...
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How do I convert seconds to hours, minutes and seconds?

...his is the best way, IMHO, as you can then use arithmetic on the timedelta and any datetime objects. – Matthew Schinckel Apr 22 '09 at 3:13 13 ...
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How do you get the logical xor of two variables in Python?

... Although this is clever and short, I'm not convinced it's clean. When someone reads this construct in the code, is it immediately obvious to them that this is an xor operation? I felt obliged to add a comment - a sign for me that I'm writing unclear...