Python: Select subset from list based on index set

Question

I have several lists having all the same number of entries (each specifying an object property):

property_a = [545., 656., 5.4, 33.]
property_b = [ 1.2,  1.3         


        

Answer 1

I see 2 options.

1. Using numpy:

   property_a = numpy.array([545., 656., 5.4, 33.])
   property_b = numpy.array([ 1.2,  1.3, 2.3, 0.3])
   good_objects = [True, False, False, True]
   good_indices = [0, 3]
   property_asel = property_a[good_objects]
   property_bsel = property_b[good_indices]
   

2. Using a list comprehension and zip it:

   property_a = [545., 656., 5.4, 33.]
   property_b = [ 1.2,  1.3, 2.3, 0.3]
   good_objects = [True, False, False, True]
   good_indices = [0, 3]
   property_asel = [x for x, y in zip(property_a, good_objects) if y]
   property_bsel = [property_b[i] for i in good_indices]