f = lambda x,y,z: (x+i*z for i in range(int((y-x)/z)))

上面不需要借助任何库就可以做分数步。

为了解决浮点精度问题，可以使用Decimal模块。

这要求在编写代码时将int或float转换为Decimal，但如果确实需要这种便利，则可以传递str并修改函数。

from decimal import Decimal


def decimal_range(*args):

    zero, one = Decimal('0'), Decimal('1')

    if len(args) == 1:
        start, stop, step = zero, args[0], one
    elif len(args) == 2:
        start, stop, step = args + (one,)
    elif len(args) == 3:
        start, stop, step = args
    else:
        raise ValueError('Expected 1 or 2 arguments, got %s' % len(args))

    if not all([type(arg) == Decimal for arg in (start, stop, step)]):
        raise ValueError('Arguments must be passed as <type: Decimal>')

    # neglect bad cases
    if (start == stop) or (start > stop and step >= zero) or \
                          (start < stop and step <= zero):
        return []

    current = start
    while abs(current) < abs(stop):
        yield current
        current += step

输出样本-

from decimal import Decimal as D

list(decimal_range(D('2')))
# [Decimal('0'), Decimal('1')]
list(decimal_range(D('2'), D('4.5')))
# [Decimal('2'), Decimal('3'), Decimal('4')]
list(decimal_range(D('2'), D('4.5'), D('0.5')))
# [Decimal('2'), Decimal('2.5'), Decimal('3.0'), Decimal('3.5'), Decimal('4.0')]
list(decimal_range(D('2'), D('4.5'), D('-0.5')))
# []
list(decimal_range(D('2'), D('-4.5'), D('-0.5')))
# [Decimal('2'),
#  Decimal('1.5'),
#  Decimal('1.0'),
#  Decimal('0.5'),
#  Decimal('0.0'),
#  Decimal('-0.5'),
#  Decimal('-1.0'),
#  Decimal('-1.5'),
#  Decimal('-2.0'),
#  Decimal('-2.5'),
#  Decimal('-3.0'),
#  Decimal('-3.5'),
#  Decimal('-4.0')]

为了精品的完整性，一个功能性的解决方案:

def frange(a,b,s):
  return [] if s > 0 and a > b or s < 0 and a < b or s==0 else [a]+frange(a+s,b,s)

下面是我的解决方案，它可以很好地使用float_range(- 1,0,0.01)，并且没有浮点表示错误。它不是很快，但工作得很好:

from decimal import Decimal

def get_multiplier(_from, _to, step):
    digits = []
    for number in [_from, _to, step]:
        pre = Decimal(str(number)) % 1
        digit = len(str(pre)) - 2
        digits.append(digit)
    max_digits = max(digits)
    return float(10 ** (max_digits))


def float_range(_from, _to, step, include=False):
    """Generates a range list of floating point values over the Range [start, stop]
       with step size step
       include=True - allows to include right value to if possible
       !! Works fine with floating point representation !!
    """
    mult = get_multiplier(_from, _to, step)
    # print mult
    int_from = int(round(_from * mult))
    int_to = int(round(_to * mult))
    int_step = int(round(step * mult))
    # print int_from,int_to,int_step
    if include:
        result = range(int_from, int_to + int_step, int_step)
        result = [r for r in result if r <= int_to]
    else:
        result = range(int_from, int_to, int_step)
    # print result
    float_result = [r / mult for r in result]
    return float_result


print float_range(-1, 0, 0.01,include=False)

assert float_range(1.01, 2.06, 5.05 % 1, True) ==\
[1.01, 1.06, 1.11, 1.16, 1.21, 1.26, 1.31, 1.36, 1.41, 1.46, 1.51, 1.56, 1.61, 1.66, 1.71, 1.76, 1.81, 1.86, 1.91, 1.96, 2.01, 2.06]

assert float_range(1.01, 2.06, 5.05 % 1, False)==\
[1.01, 1.06, 1.11, 1.16, 1.21, 1.26, 1.31, 1.36, 1.41, 1.46, 1.51, 1.56, 1.61, 1.66, 1.71, 1.76, 1.81, 1.86, 1.91, 1.96, 2.01]

f = lambda x,y,z: (x+i*z for i in range(int((y-x)/z)))

上面不需要借助任何库就可以做分数步。

避免四舍五入问题的技巧是使用一个单独的数字在范围内移动，该数字在开始前半步开始。

# floating point range
def frange(a, b, stp=1.0):
  i = a+stp/2.0
  while i<b:
    yield a
    a += stp
    i += stp

另外,numpy。可以使用Arange。