Creating an array of random circles inside of a RSVP

Hi all! I’m in desperate need of help, since I am mostly self-taught in coding and I can’t seem to figure out this one. Basically, i am trying to recreate the second experiment of this study: On the nature of the stimulus information necessary for estimating mean size of visual arrays - PMC

I need to create two arrays of circles, each containing 7 circles. Each circle can be either “small” or “large” – the larger ones being 20% bigger in diameter. Each array contains a random selection of “large” and “small” circles. Now, the real problem is that these arrays need to appear as T2 during a RSVP task.

So, this is my code for the RSVP:

from psychopy import visual, core, event
import random
import string

num_stimuli = 20
target_positions = [11, 14] 

stimuli = [ ]

for i in range(num_stimuli):
  if i in target_positions:
    stimulus = str(random.randint(0, 9))
    stimulus = random.choice(string.ascii_uppercase)

text_stim = visual.TextStim(win, text='', color="white")

for stimulus in stimuli:
text_stim.text = stimulus 

but i can’t seem to understand how i should implement the two circles arrays as T2