Python: More efficient way to get random slices from several lists

Question

Here's a piece of python code I wrote to get random characters from 4 lists and append them to a separate list:

key.append(chr(upper[randint(0,len(upper)-1)]))
key.append(chr(lower[randint(0,len(lower)-1)]))
key.append(chr(nums[randint(0,len(nums)-1)]))
key.append(chr(symbols[randint(0,len(symbols)-1)]))

Is there a more elegant way to do this?

Answer 1

I'd recommend using random.choice + list.extend :

lsts = [upper, lower, nums, symbols]    
key.extend(chr(random.choice(x)) for x in lsts)

Answer 2

random.choice( seq )

Return a random element from the non-empty sequence seq . If seq is empty, raises IndexError .

source

key.append(chr(random.choice(upper)))