使用一对列表中的部分而非全部元素创建多个字典

Question

I would like, from a pair of lists, say:

a = ['str1', 'str2', 'str3', 'str4', 'str5']
b = [var1, var2, var3, var4, var5]

to be able to create multiple dictionaries, with arbitrarily selected pairs of elements from a (as keyword) and b (as value). I have found in a comment on an answer to this question , the following method:

full_set = dict(zip(a,b))
subset = {i:full_set[i] for i in a if i not in ['str2', 'str5']}

which produces subset dictionary:

{'str1': var1, 'str3': var3, 'str4': var4}

This works fine, but I am curious as to whether there is an equally short or shorter method of building subset dictionaries from the two lists, eg via specifying the list indices for the elements I want included, without creating a full dictionary containing all elements first.

For context, my vars refer to scikit-learn estimator objects.

Answer 1

You can combine both statements into one:

avoid = {'str2', 'str5'} # Sets have better lookup time :)
{k:v for k,v in zip(a,b) if k not in avoid}

Answer 2

Probably convert this to numpy arrays and use fancy indexing like this:

import numpy as np

a = np.array(['str1', 'str2', 'str3', 'str4', 'str5'])
b = np.array([1,2,3,4,5])

indices = [0, 1, 4]

d = dict(zip(a[indices],b[indices]))

d returns:

{'str1': 1, 'str2': 2, 'str5': 5}