joaoricardo000 joaoricardo000 - 1 year ago 107
Python Question

Regex to remove bit signal noise spikes

I am dealing with RF signals that sometimes have noise spikes.

The input is something like this:


Before parsing the data in the signal, I need to remove the spike bits, that are 0's and 1's sequence with a lenght lower than (in this example) 3.

So basically I need to match

After match, I replace it by the bit before it, so a clean signal look like this:

So far I achieved this with two different Regex:

self.re_one_spikes = re.compile("(?:[^1])(?P<spike>1{1,%d})(?=[^1])" % (self._SHORTEST_BIT_LEN - 1))
self.re_zero_spikes = re.compile("(?:[^0])(?P<spike>0{1,%d})(?=[^0])" % (self._SHORTEST_BIT_LEN - 1))

Then I iterate on the matches and replace.

How can I do this with a single regex? And can I use regex to replace different sizes matches?

I tried something like this with no success:


Answer Source
import re

def fixer(match):
    ones =
    if len(ones) < THRESHOLD: return "0"*len(ones)
    return ones

my_string = '00000001111100011110001111100001110000001000001111000000111001111000'

if you want to also remove "spikes" of zeros

def fixer(match):
    items =
    if len(items) < THRESHOLD: return "10"[int(items[0])]*len(items)
    return items

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