SciPy – 常量

Scipy代表科学Python ，在任何科学/数学计算中，我们经常需要通用常量来执行任务，一个著名的例子是计算圆的面积 = 'pi*r*r'，其中 PI = 3.14...或更复杂的一个喜欢发现力_重力= G*M*m ⁄（距离） ²其中 G = 引力常数。在所有这些情况下，如果我们有参考资料来查找这些常数并将它们轻松地合并到我们的计算中，那将非常方便。

Scipy-Constants 是 Scipy 库中的一个子模块，它为我们完成了这项工作。它包含通用数学常数、物理常数和单位的详尽列表。只需 1 行代码即可查找。

访问常量

只需在“ scipy.constants.XXXX ”格式中输入常量名称代替 XXXX 即可访问其值。下面列出了使用 scipy.constant 模块的一些最重要的常量。该列表并不详尽，但它提供了如何访问常量的好主意。

Python3

# import module
import scipy
 
# Just type the name of the constant in
# scipy.constant.XXXX format to access its value.
print("sciPy - pi:", scipy.constants.pi)
print("Golden ratio:", scipy.constants.golden_ratio)
print("Speed of light in vaccum:", scipy.constants.c)
print("Gravitational Constant:", scipy.constants.G)
print("Molar Gas Constant:", scipy.constants.R)
print("Boltzman Constant:", scipy.constants.k)
print("Proton mass Constant:", scipy.constants.proton_mass)

Python3

import scipy
 
 
# find method looks up in the dictorary and
# finds out all the constants containing
# 'electron' word in it and returns a list
# of constants.
res = scipy.constants.find("electron")
print(res, end='\n')

Python3

import scipy
 
 
# This returns a tuple (value, unit, uncertainty)
# associated with the physical constant
print(scipy.constants.physical_constants['alpha particle mass'])

Python3

import scipy
 
# Area of a circle using
# scipy.constants.pi
def Area_of_Circle(r):
    return scipy.constants.pi * r * r
 
# Calculates the gravational for
def force_gravity(M, m, dist):
    return (scipy.constants.G*M*m) / (dist**2)
 
 
print(f'Area of Circle: {Area_of_Circle(5)}')
print(f'Gravitational force: {force_gravity(10,5,1)}')

输出：

寻找常数

我们可以使用内置方法来查找与我们的用例相关的常量。常量使用字典数据结构存储，我们可以使用scipy. constants.find() API 来查找所有相关的常量从 dict 并相应地使用它们。

下面的代码演示了如何使用 scipy。常量.find() API。下面的代码打印了所有包含“电子”字的常量，我们可以过滤掉需要的常量。

蟒蛇3

import scipy
 
 
# find method looks up in the dictorary and
# finds out all the constants containing
# 'electron' word in it and returns a list
# of constants.
res = scipy.constants.find("electron")
print(res, end='\n')

输出：

不仅是常量的大小，我们还可以使用格式访问与存储在 scipy.constants 模块中的任何 physical_constants 的大小相关的单位和不确定度

physical_constants[name] = (value, unit, uncertainty).

编程需要懂一点英语

蟒蛇3

import scipy
 
 
# This returns a tuple (value, unit, uncertainty)
# associated with the physical constant
print(scipy.constants.physical_constants['alpha particle mass'])

输出：

(6.6446573357e-27, 'kg', 2e-36)

例子：

蟒蛇3

import scipy
 
# Area of a circle using
# scipy.constants.pi
def Area_of_Circle(r):
    return scipy.constants.pi * r * r
 
# Calculates the gravational for
def force_gravity(M, m, dist):
    return (scipy.constants.G*M*m) / (dist**2)
 
 
print(f'Area of Circle: {Area_of_Circle(5)}')
print(f'Gravitational force: {force_gravity(10,5,1)}')

输出：

除了上述变量外，scipy.constants 还包含更多的物理常量，下面列出了 scipy.constants 模块中所有可用的方法，并附有说明。

以下是 SciPy 模块中最常用的常量：

Constants	Description
pi	Mathematical pi value
golden	Mathematicalgolden ratio
c	Speed of light in vacuum
speed_of_light	Speed of light in vacuum
G	Standard acceleration of gravity
G	Newton Constant of gravitation
E	Elementary charge
R	Molar gas constant
Alpha	Fine-structure constant
N_A	Avagadro constant
K	Boltzmann constant
Sigma	Stefan-Boltzmann constant σ
m_e	Electron mass
m_p	Proton mass
m_n	Neutron Mass
H	Plank Constant
Plank constant	Plank constant h

以下是 SciPy 模块中可用的单位常量：

大量的：

Unit	Description
Gram	One gram in Kilogram.
Grain	One grain in Kilogram.
Pound	One Pound in Kilogram.
Ounce	One Ounce in Kilogram.
automic_mass	Atomics mass constant in Kilogram.

时间：

Unit	Description
Minute	One minute in seconds.
Hour	One hour in seconds.
Day	One day in seconds.
Year	One year in seconds.

长度：

Units	Description
Inch	One inch in meters.
Foot	One foot in meters.
Yard	One yard in meters.
Pt	One point in meters.
Micron	One Micron in meters.

压力：

Units	Description
Atm	The standard atmosphere in pascals.
Atmosphere	The standard atmosphere in pascals.
Bar	One bar in Pascals.
Torr	One torr(mmHg) in pascals.

区域：

Units	Description
Hectare	One hectare in square meters.
Acre	One acre in square meters.

速度：

Units	Description
Kmh	Kilometer per hour in meter per second.
Mph	Miles per hour in meter per second.
Mach	One Match in meter per second.