When I ran this script (Python v2.6): a = [1,2] b = a a.append(3) print a >>>> [1,2,3] print b >>>> [1,2,3] I expected print b to output [1,2]. Why did b get changed when all I did was change a? Is b permanently tied to a? If so, can I make them independent? How? … Read more
“create a default value based on the instance name of the class
without passing in an extra argument.”
I am using python to work out how many children would be born in 5 years if a child was born every 7 seconds. The problem is on my last line. How do I get a variable to work when I’m printing text either side of it?
I have a function where I need to do something to a string. I need the function to return a boolean indicating whether or not the operation succeeded, and I also need to return the modified string. In C#, I would use an out parameter for the string, but there is no equivalent in Python. … Read more
I have been studying Python, and I read a chapter which describes the None value, but unfortunately this book isn’t very clear at some points. I thought that I would find the answer to my question, if I share it there.
“global name ‘_total’ is not defined”
Peter Norvig has an essay describing a program to solve sudoku puzzles, even the hardest ones, by combining deterministic logical operations and smart traversal of the possible solutions. The latter is done recursively; here’s that function (source): def search(values): "Using depth-first search and propagation, try all possible values." if values is False: return False ## … Read more
Let’s take a simple code: y = [1,2,3] def plusOne(y): for x in range(len(y)): y[x] += 1 return y print plusOne(y), y a = 2 def plusOne2(a): a += 1 return a print plusOne2(a), a Values of ‘y’ change but value ‘a’ stays the same. I have already learned that it’s because one is mutable … Read more
Is there are more readable way to check if a key buried in a dict exists without checking each level independently?
I want to use a bunch of local variables defined in a function, outside of the function. So I am passing x=locals() in the return value.