'float' 对象没有属性 '__getitem__' Python 错误
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'float' object has no attribute '__getitem__' Python error
提问by Jonny
When I run the code
当我运行代码
import numpy as np
from scipy.integrate import odeint
import matplotlib.pyplot as plt
# Initial conditions
def f_func(eta,y_in):
y_out = np.zeros(3)
y_out[0] = y_in[1]
y_out[1] = y_in[2]
y_out[2] = -y_in[0]*y_in[2]/2
return y_out
eta = np.linspace(0,8,100)
X0 = [0,0,0.33206]
X = odeint(f_func,X0,eta)
I get the error
我收到错误
'float' object has no attribute '__getitem__'
When I run the following MATLAB program, everything works OK. The MATLAB function ode45 is equivalent to Pythons' odeint.
当我运行以下 MATLAB 程序时，一切正常。MATLAB 函数 ode45 等效于 Python 的 odeint。
main program:
主程序：
clear
global beta
beta = 1;
initial_value = [0,0,1.2322];
eta = linspace(0,4,100)
[x_out, y_out] = ode45(@falkner_skan,eta,initial_value);
plot(x_out,y_out(:,2))
falkner_skan function:
falkner_skan 函数：
function y_out = falkner_skan(x,y_in)
global beta
y_out(1,1) = y_in(2);
y_out(2,1) = y_in(3);
y_out(3,1) = -y_in(1)*y_in(3) - beta*(1-y_in(2)^2);
end
Thisand thisand thisthread does not seem to give me any guidance.
采纳答案by Mattias Farnemyhr
It seems as though y_inis not a list but a float value. The error rises because you're trying to get an item with obj[x]of an object which doesn't support it.
似乎y_in不是列表而是浮点值。错误上升是因为您试图获取obj[x]不支持它的对象的项目。
Looking at the documentation for odeintit says that the input function should take two arguments, the first being your data object and the second should be a float. Your implementation of f_funcis therefore wrong.
查看 odeint的文档，它说输入函数应该有两个参数，第一个是你的数据对象，第二个应该是一个浮点数。f_func因此，您的实现是错误的。
回答by Stav Bodik
NumPy has float 64 object which has item() function, np.float64(10.5).item()
NumPy 有 float 64 对象，它有 item() 函数，np.float64(10.5).item()
回答by Marjan Radfar
I had the same issue. According to documentation for odeint, in f_func(eta,y_in), change the order of eta and y_in, i.e. write it as f_func(y_in, eta) or set the argument tfirstto be True.
我遇到过同样的问题。根据odeint 的文档，在 f_func(eta,y_in) 中，更改 eta 和 y_in 的顺序，即将其写为 f_func(y_in, eta) 或将参数tfirst设置为True。
