Python – 圆润的numpy？

def round_(a,decimals=0,out=None):
    return around(a,decimals=decimals,out=out)

def around(a,out=None):
    """
    Evenly round to the given number of decimals.

    Notes
    -----
    For values exactly halfway between rounded decimal values,NumPy
    rounds to the nearest even value. Thus 1.5 and 2.5 round to 2.0,-0.5 and 0.5 round to 0.0,etc. Results may also be surprising due
    to the inexact representation of decimal fractions in the IEEE
    floating point standard [1]_ and errors introduced when scaling
    by powers of ten.

    Examples
    --------
    >>> np.around([0.37,1.64])
    array([ 0.,2.])
    >>> np.around([0.37,1.64],decimals=1)
    array([ 0.4,1.6])
    >>> np.around([.5,1.5,2.5,3.5,4.5]) # rounds to nearest even value
    array([ 0.,2.,4.,4.])
    >>> np.around([1,2,3,11],decimals=1) # ndarray of ints is returned
    array([ 1,11])
    >>> np.around([1,decimals=-1)
    array([ 0,10])

    """

例：

如果你需要打印字符串,你可以格式化它,给你正确的答案：

import numpy as np

num = np.float64(1) * np.float64(85000) * np.float64(7.543709)
print(num)
print(float("{0:.2f}".format(num)))
print(np.round(num,2))
print()

num += 0.02
print(num)
print(float("{0:.2f}".format(num)))
print(np.round(num,2))

给你

641215.265
641215.27
641215.26

641215.285
641215.29
641215.28