Python a &= b meaning?
What does the &= operator mean in Python, and can you give me a working example? I am trying to understand the __iand__ operator. I just don’t know what &= means and have looked online but couldn’t find it.
in-place
How to sort in-place using the merge sort algorithm?
Knuth left this as an exercise (Vol 3, 5.2.5). There do exist in-place merge sorts. They must be implemented carefully. First, naive in-place merge such as described here isn’t the right solution. It downgrades the performance to O(N2). The idea is to sort part of the array while using the rest as working area for merging. For example … Read more
Is Quicksort in-place or not?
Intro to Algorithms from MIT Press qualifies QuickSort as in-place – it sorts the elements within the array with at most a constant amount of them outside the array at any given time. At the end of the day, people will always have differing opinions (is Top-Down Memoization considered Dynamic Programming? Not to some “classical” folks), side with who you … Read more
How to delete from a text file, all lines that contain a specific string?
To remove the line and print the output to standard out: To directly modify the file – does not work with BSD sed: Same, but for BSD sed (Mac OS X and FreeBSD) – does not work with GNU sed: To directly modify the file (and create a backup) – works with BSD and GNU … Read more
Python Math – TypeError: ‘NoneType’ object is not subscriptable
This should be The .sort() method is in-place, and returns None. If you want something not in-place, which returns a value, you could use Aside #1: please don’t call your lists list. That clobbers the builtin list type. Aside #2: I’m not sure what this line is meant to do: is it simply ? In other words, I … Read more