Python array reference variables elsewhere

Question

Struggling to find an answer as I'm not sure on the exact wording I need so apologies.

Part of my script creates an array of values but I'm trying to reference these elsewhere to save speed. I have

def frame1():
  data = array.array('B' [1,2,3,4,5])

However I need to input 512 values into 720 frames and don't want to do this manually. I want to be able to make a variable thats

hour = 1,3,5
minute = 2,4,6

and combine them in a frame to have

data = array.array('B' [hour + minute + minute])

to result in

data = array.array('B' [1,3,5,2,4,6,2,4,6])

Hopefully that makes sense!!

well, isn't that just [1, 2, 3] + [2, 4, 6] * 2? Btw your syntax for the function call isn't correct, missing a comma between the args — Chase
– Chase, Commented Dec 29, 2020 at 13:39

chepner · Accepted Answer · 2020-12-29 13:49:07Z

2

Both hour and minute are already lists, and so hour + minute is as well. You don't need to do anything special to make the new combined list from the sum; the sum is the combined list.

data = array.array('B', hour + minute + minute)

Strictly speaking, this is inefficient, as repeatedly concatenating two lists results in O(n^2) behavior. A better solution for more, longer lists would be to use itertools.chain.

from itertools import chain

data = array.array('B', chain(hour, minute, minute))

Depending on your actual code, this may or may not make an appreciable difference in the running time.

answered Dec 29, 2020 at 13:49

chepner

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1 Comment

Adam Davies Over a year ago

I knew it would be simple! It would appear I was getting bogged down in too many layers of brackets. Thank you!

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