python怎么保留小数

a = 12.345

print("%.2f" % a)

# 12.35

a = 12.345

a1 = round(a, 2)

print(a1)

# 12.35

from decimal import Decimal

a = 12.345

Decimal(a).quantize(Decimal("0.00"))

Decimal('12.35')

a = 12.345

str(a).split('.')[0] + '.' + str(a).split('.')[1][:2]

'12.34'

import re

a = 12.345

re.findall(r"\d{1,}?\.\d{2}", str(a))

['12.34']