Python保留指定位数小数的5种方法总结

# 四舍五入方法
a = 2.345566
print('%.4f'% a)
# 2.3456
print('%.3f'% a)
# 2.346
print('%.2f'% a)
# 2.35
# 赋值给新的变量
c = '%.2f'% a
print(c)
# 2.35

# 四舍五入方法
a = 2.345566
print(format(a, '.4f'))
# 2.3456
print(format(a, '.3f'))
# 2.346
# 赋值给新的变量
c = format(a, '.4f')
print(c)
# 2.3456

a = 2.345566
c = int(a * 100) / 100
print(c)
# 2.34

a = 2.345566
c = int(a * 1000) / 1000
print(c)
# 2.345

a = 2.345566
c = int(a * 10000) / 10000
print(c)
# 2.3455

a = 2.345566
# 进行分割
a_0 = str(a).split('.')[0]
a_1 = str(a).split('.')[1]
# 截取小数点后的
a_point = a_1[0:2] # 截取2位
# 字符串连接
a_new = a_0 + '.' + a_point
# 将string类型转换为float类型
a_new_number = float(a_new)
print(a_new_number)
# 2.34

import numpy as np
a = np.random.random(3)
print('before set precision: \n',a)
np.set_printoptions(precision=3, suppress=True)
print('after set precision: \n',a)
np.set_printoptions(formatter={'float': '{: 0.3f}'.format})
print('after set formatter: \n',a)
# before set options:
# [ 0.05856348 0.5400039 0.70000603]
# after set precision:
# [ 0.059 0.54 0.7]
# after set formatter:【强制补0】
# [ 0.059 0.540 0.700]