django.我怎样才能在模型中做一些数学运算

Question

为了我的研究项目，我正试图从php迁移到django。用户可以为该值创建3个变量，如最小值、最大值和步长。从中我生成了列表，然后我试图做一些数学运算，并将结果呈现为表，但我无法理解如何正确处理。这是我在python上可怕的原型代码：

import numpy as np
mcharge = np.arange(0.01, 0.38, 0.01)
charge = np.arange(20, 57, 1)
mdiscount = np.arange(0.001, 0.013, 0.001)
discount = np.arange(5, 23, 1.5)
clist = charge.tolist()
mlist = mcharge.tolist()
mdlist = mdiscount.tolist()
dlist = discount.tolist()

result_sum_n_m_n = [(x + y) / 100 for x,y in zip(charge, margin)]
result_sum_s_m_s = [(x + y) / 100 for x,y in zip(mdiscount, discount)]
result_sum_a = [ '%.4f' % elem for elem in result_sum_n_m_n ]
result_sum_b = [ '%.4f' % elem for elem in result_sum_s_m_s ]
n_m_n = result_sum_a * 12
n_m_n.sort()
s_m_s = result_sum_b * 37
n_m = [float(i) for i in n_m_n]
s_m = [float(i) for i in s_m_s]
multiply = [(x * y) for x,y in zip(n_m, s_m)]
minus = [(x- y) for x, y in zip(n_m, s_m)]
last_minus = [(x - y) for x, y in zip(minus, multiply)]
con = [(x / y) for x, y in zip(n_m, last_minus)]
print('result {}, len {}'.format(con, len(con)))

结果它创建了矩阵12x37，就像这样：

1.4283164995181838, 1.6389078861692066, 1.9223379318295355, 2.3242982675208066, 2.9439896046711893, 4.004603793386458, 6.259777970274032, 14.329202140572251, -49.56638700424323, -9.079561186305252, -4.997501249375312, -3.4475326365561463, 
1.4042354198677265, 1.5980294517892306, 1.8538770902420096, 2.2072644412008695, 2.7313961644544786, 3.574587978568797, 5.170847049689823, 9.343061021478366, 48.37766802148688, -15.223037046585988, -6.5767613173797335, -4.194435010402278, 
.....

这是我尝试使用的模型

class Margin(models.Model):
minimal = models.DecimalField()
maximal = models.DecimalField()
step = models.DecimalField()
def gen_range_margin(self):
margin = np.arange(self.minimal, self.maximal, self.step)
return margin
class Charge(models.Model):
minimal = models.DecimalField()
maximal = models.DecimaField()
step = models.DecimaField()
def gen_range_charge(self):
charge = np.arange(self.minimal, self.maximal, self.step)
return charge
.......
.......
class Calculus(models.Model):
product = models.OneToOneField(Product)
margin = models.OneToOneField(Margin)
charge = models.OneToOneField(Charge)
mdiscount = models.OneToOneField(Mdiscount)
discount = models.OneToOneField(Discount)

那么，我如何将生成矩阵的代码(我知道它一团糟(放在我的模型中，以及如何正确地执行它呢？可能我需要在应用程序中创建一些filters。

Answer 1

如果您使用PostgreSql作为数据库，那么您可以使用ArrayField，在该字段中您可以直接存储计算后的数组。例如：

class Margin(models.Model):
...
@property
def gen_range_margin(self):
margin = np.arange(self.minimal, self.maximal, self.step)
return margin
class Charge(models.Model):
...
@property
def gen_range_charge(self):
charge = np.arange(self.minimal, self.maximal, self.step)
return charge
from django.contrib.postgres.fields import ArrayField
class Calculus(models.Model):
result = ArrayField(ArrayField(models.DecimalField()))
...
def do_the_math(self):
# your calculation
self.result = result_as_array
def save(self, *args, **kwargs):
self.do_the_math()
return super(Calculus, self).save(*args, **kwargs)