交换字典项目 python

Question

I am trying to swap items by index inside one python dict, here is my data structure

{'A': [4, 7], 'B': [5, 1], 'C': [0, 5], 'D': [1, 3], 'E': [3, 0], 'F': [2, 6], 'G': [7, 2], 'H': [6, 4]}

I want to swap items for example like this:

 {'F': [2, 6], 'B': [5, 1], 'C': [0, 5], 'D': [1, 3], 'E': [3, 0], 'A': [4, 7], 'G': [7, 2], 'H': [6, 4]}

Answer 1

I would convert the dict to a list first:

d = {'A': [4, 7], 'B': [5, 1], 'C': [0, 5], 'D': [1, 3], 'E': [3, 0], 'F': [2, 6], 'G': [7, 2], 'H': [6, 4]}
l = list(d.items())
l[i1], l[i2] = l[i2], l[i1]
d = dict(l)

Answer 2

You can't reorder a dict arbitrarily without rebuilding it (a bunch of targeted pop s and reinsertions could do it piece by piece, but it would be absurdly complicated to little or no benefit). If you want to swap the position of two key/value pairs, your best option is to convert to a list of such pairs, swap the indices, then convert back to dict , eg:

population = {'A': [4, 7], 'B': [5, 1], 'C': [0, 5], 'D': [1, 3], 'E': [3, 0], 'F': [2, 6], 'G': [7, 2], 'H': [6, 4]}
population = list(population.items())
population[indexA], population[indexB] = population[indexB], population[indexA]
population = dict(population)

This is O(n) work to be clear (done once to convert to list , again to convert back to dict ); if you actually need to do it repeatedly, I'd suggest sticking to a list without converting to a dict at all.