import re
str_in = '4|5|0.00000000|'
expected_str_out = '4|5|0.0|'
str_out = re.sub(r'(?<![^|])0+\.0+(?![^|])', '0.0', str_in)
print( str_out == expected_str_out )
aW1wb3J0IHJlCgpzdHJfaW4gPSAnNHw1fDAuMDAwMDAwMDB8JwpleHBlY3RlZF9zdHJfb3V0ID0gJzR8NXwwLjB8JwoKc3RyX291dCA9IHJlLnN1YihyJyg/PCFbXnxdKTArXC4wKyg/IVtefF0pJywgJzAuMCcsIHN0cl9pbikKcHJpbnQoIHN0cl9vdXQgPT0gZXhwZWN0ZWRfc3RyX291dCAp