How to add an element to the beginning of an OrderedDict?

There’s no built-in method for doing this in Python 2. If you need this, you need to write a prepend() method/function that operates on the OrderedDict internals with O(1) complexity. For Python 3.2 and later, you should use the move_to_end method. The method accepts a last argument which indicates whether the element will be moved … Read more

ImportError: DLL load failed: %1 is not a valid Win32 application for Python Matplotlib

The error that you are getting is because you have installed the wrong component of matplotlib (there are the 32 bit and 64 bit components). This page provides you all binaries (32bit,64bit) for Windows. It also includes other packages apart from matplotlib if you may be needing them in the future. Try installing the proper … Read more

Replace list of list with “condensed” list of list while maintaining order

Here’s a brute-force approach (it might be easier to understand): from itertools import chain def condense(*lists): # remember original positions positions = {} for pos, item in enumerate(chain(*lists)): if item not in positions: positions[item] = pos # condense disregarding order sets = condense_sets(map(set, lists)) # restore order result = [sorted(s, key=positions.get) for s in sets] … Read more