Question

我对以下代码有疑问。我尝试了很多网页来找到一些解决方案，但我无法做到。问题是当我仅打印4行后运行此脚本时，Python会重新启动外壳程序。在jupyter中，它发送消息：The kernel appears to have died. It will restart automatically.

我尝试在脚本的第一个文件中读取一个文件，该文件包含（300,000）行数据。然后在计算了ODE和其他函数之后，我希望将结果打印出来进行比较

import numpy as np
from scipy.integrate import odeint
from math import *
from scipy.integrate import quad  
import math
import pandas as pd

hr, dr, cr, br = np.genfromtxt('outputs/new.txt',unpack=True)

def OD_H(od, z, c, b):
   Omegai = (1-od)
   div1 = np.divide(1, (1 + z), where = (1 + z)!= 0)     
   dMdt = -(div1) * (2 *(1-od)* (-2 + (od/(6 * c))) + 3 - 3 * b**2 * Omegai - 3 * od)
return dMdt

def ant(H0, z, od0, c, b):
    z1 = 0
    od = odeint(OD_H, od0, [z1, z], args=(c, b))[-1]                   
    return od   

def dec(H0, z, od0, c, b):
    od = ant(H0, z, od0, c, b)
    q = -1 - (-2 + od/(6 * c))
    return q

for i in range(len(hr)):
    for z in range (0,1):
        print(dec(hr[i], z, dr[i], cr[i], br[i]),hr[i], dr[i], cr[i], br[i])

这是一个简单的代码，但是我不知道最终的问题是什么。非常感谢您的帮助。

输入文件（new.txt）可能是

71.076588184266 0.40147988209522 0.080396967668756 0.050302016457046
71.02284157687 0.39756707964421 0.080918035449145 0.050501956013259
71.102923163306 0.41587392748136 0.07823452108922 0.049336707395359
70.860444589498 0.46748446539443 0.072392464271658 0.046667808684486
70.181278149341 0.44888833570037 0.077917371645449 0.04777288009128
70.588452406351 0.49035265611716 0.072303154996487 0.045942096884044
70.588452406351 0.49035265611716 0.072303154996487 0.045942096884044
70.011812869146 0.44210637315163 0.07871914246357 0.048393990901086
69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
70.123419349447 0.43961350279409 0.07862300319627 0.048607832896286
70.361666430312 0.41397677666087 0.080502527828865 0.049745843125116
70.361666430312 0.41397677666087 0.080502527828865 0.049745843125116
70.357430153315 0.41485946940097 0.08042642593323 0.049703105696664
70.357430153315 0.41485946940097 0.08042642593323 0.049703105696664
71.551080656041 0.51047305096688 0.066682530098241 0.0446474321235

Answer 1

好的，问题出在odeint上。 docs建议改用solve_ivp。

现在完全免责声明，我绝对不知道这意味着什么，事物的数学和含义超出了我的理解。但是，我尝试使用solve_ivp来最好地模仿odeint行为，该函数开箱即用不接受args。向救援人员展示贫民窟Lambda。

od = odeint(OD_H, od0, [z1, z], args=(c, b))[-1] #before
od = solve_ivp(lambda od, z: OD_H(od, z, c, b), t_span = [z1, z], y0 = [od0])['y'][-1][-1] #after

请注意，这并非完全替代，resolve ivp的结果以这种方式呈现浮点数，并且您希望将其包装为[od]而不是完全匹配旧结果。至于我用来缩小odeint的最小代码，您可以在下面看到战场。

import numpy as np
from scipy.integrate import odeint, solve_ivp
#from math import *
from scipy.integrate import quad  
#import math
#import pandas as pd

hr, dr, cr, br = np.genfromtxt('new.txt',unpack=True)




def OD_H(od, z, c, b):
   Omegai = (1-od)
   div1 = np.divide(1, (1 + z), where = (1 + z)!= 0)     
   dMdt = -(div1) * (2 *(1-od)* (-2 + (od/(6 * c))) + 3 - 3 * b**2 * Omegai - 3 * od)
   return dMdt

def ant(H0, z, od0, c, b):
    z1 = 0
    #od = odeint(OD_H, od0, [z1, z], args=(c, b))[-1] #this solver crashed
    od = solve_ivp(lambda od, z: OD_H(od, z, c, b), t_span = [z1, z], y0 = [od0])['y'][-1][-1] #this worked out. perhaps wrap in square brackets [od] if needed.
    #od = OD_H(od0,z,c,b)  #this alone without the solvers worked fine              
    return od   

#def dec(H0, z, od0, c, b): #remove the middleman
#    od = ant(H0, z, od0, c, b)
#    q = -1 - (-2 + od/(6 * c))
#    return od

for i in range(5): #simple check instead
    z = 0 #you do not need a loop here
    res = ant(hr[i], z, dr[i], cr[i], br[i])
    print(res)
        #print(dec(hr[i], z, dr[i], cr[i], br[i]),hr[i], dr[i], cr[i], br[i]) print was not the culprit

最重要的是，我还不知道为什么odeint会以这种方式崩溃。

编辑：

对于操作，这将是更新代码的样子。

import numpy as np
from scipy.integrate import odeint, solve_ivp
#from math import *
from scipy.integrate import quad  
#import math
#import pandas as pd

hr, dr, cr, br = np.genfromtxt('new.txt',unpack=True)

def OD_H(od, z, c, b):
   Omegai = (1-od)
   div1 = np.divide(1, (1 + z), where = (1 + z)!= 0)     
   dMdt = -(div1) * (2 *(1-od)* (-2 + (od/(6 * c))) + 3 - 3 * b**2 * Omegai - 3 * od)
   return dMdt

def ant(H0, z, od0, c, b):
    z1 = 0
    #od = odeint(OD_H, od0, [z1, z], args=(c, b))[-1]  
    od = [solve_ivp(lambda od, z: OD_H(od, z, c, b), t_span = [z1, z], y0 = [od0])['y'][-1][-1]]
    return od   

def dec(H0, z, od0, c, b):
    od = ant(H0, z, od0, c, b)
    q = -1 - (-2 + od/(6 * c))
    return q

for i in range(len(hr)):
    for z in range (0,1):
        print(dec(hr[i], z, dr[i], cr[i], br[i]),hr[i], dr[i], cr[i], br[i])

以上数据的输出如下：

[0.16771346] 71.076588184266 0.40147988209522 0.080396967668756 0.050302016457046
[0.18113212] 71.02284157687 0.39756707964421 0.080918035449145 0.050501956013259
[0.11404428] 71.102923163306 0.41587392748136 0.07823452108922 0.049336707395359
[-0.07627332] 70.860444589498 0.46748446539443 0.072392464271658 0.046667808684486
[0.03981973] 70.181278149341 0.44888833570037 0.077917371645449 0.04777288009128
[-0.13031641] 70.588452406351 0.49035265611716 0.072303154996487 0.045942096884044
[-0.13031641] 70.588452406351 0.49035265611716 0.072303154996487 0.045942096884044
[0.06395836] 70.011812869146 0.44210637315163 0.07871914246357 0.048393990901086
[0.15976794] 69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
[0.15976794] 69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
[0.15976794] 69.807956729005 0.41349634394633 0.082020266421564 0.049900569076028
[0.06809821] 70.123419349447 0.43961350279409 0.07862300319627 0.048607832896286
[0.14293214] 70.361666430312 0.41397677666087 0.080502527828865 0.049745843125116
[0.14293214] 70.361666430312 0.41397677666087 0.080502527828865 0.049745843125116
[0.14029196] 70.357430153315 0.41485946940097 0.08042642593323 0.049703105696664
[0.14029196] 70.357430153315 0.41485946940097 0.08042642593323 0.049703105696664
[-0.27587903] 71.551080656041 0.51047305096688 0.066682530098241 0.0446474321235

我可以用来比较的代码是这个。注意旧的odeint求解器，但只打印了4个值。

import numpy as np
from scipy.integrate import odeint, solve_ivp
#from math import *
from scipy.integrate import quad  
#import math
#import pandas as pd

hr, dr, cr, br = np.genfromtxt('new.txt',unpack=True)

def OD_H(od, z, c, b):
   Omegai = (1-od)
   div1 = np.divide(1, (1 + z), where = (1 + z)!= 0)     
   dMdt = -(div1) * (2 *(1-od)* (-2 + (od/(6 * c))) + 3 - 3 * b**2 * Omegai - 3 * od)
   return dMdt

def ant(H0, z, od0, c, b):
    z1 = 0
    od = odeint(OD_H, od0, [z1, z], args=(c, b))[-1]  
    #od = [solve_ivp(lambda od, z: OD_H(od, z, c, b), t_span = [z1, z], y0 = [od0])['y'][-1][-1]]
    return od   

def dec(H0, z, od0, c, b):
    od = ant(H0, z, od0, c, b)
    q = -1 - (-2 + od/(6 * c))
    return q

for i in range(4): #simplified to avoid crash
    for z in range (0,1):
        print(dec(hr[i], z, dr[i], cr[i], br[i]),hr[i], dr[i], cr[i], br[i])

输出：

[0.16771346] 71.076588184266 0.40147988209522 0.080396967668756 0.050302016457046
[0.18113212] 71.02284157687 0.39756707964421 0.080918035449145 0.050501956013259
[0.11404428] 71.102923163306 0.41587392748136 0.07823452108922 0.049336707395359
[-0.07627332] 70.860444589498 0.46748446539443 0.072392464271658 0.046667808684486

您提供的代码并不总是生成负值。我不能理解您为什么会期望或希望他们这样做，但是结果应该与原始代码匹配。

Answer 2

您的代码将按预期工作，但有一点点更改：避免零长度的积分间隔（如果遇到此间隔，请直接返回初始值）。

def ant(H0, z, od0, c, b):
    z1 = 0
    if type(od0) is np.float64: od0 = np.array([od0]); # for uniform output
    od = od0 if abs(z-z1) < 1e-15 else odeint(OD_H, od0, [z1, z], args=(c, b))[-1]                   
    return od

当我尝试做数学运算时，Python重新启动Shell

2 个答案: