我在嵌套 for 循环中的索引时遇到问题。 Python 吐出一个索引错误,告诉我我的索引超出范围。
下面是我的代码和随后的错误:
from math import *
import numpy as np
from scipy import integrate
import matplotlib.pyplot as plt
import os
croot = 1
ctip = 1
span = 1
thetaroot = 0
thetatip = 0
a0root = 0.11
a0tip = 0.11
alpha = 0
alpha0root = -2.5
alpha0tip = -2.5
thetaroot = thetaroot * arctan(1.) / 45.
thetatip = thetatip * arctan(1.) / 45.
alpha = alpha * arctan(1.) / 45.
alpha0root = alpha0root * arctan(1.) / 45.
alpha0tip = alpha0tip * arctan(1.) / 45.
n = 10
theta = np.empty(n, dtype = object)
y = np.empty(n, dtype = object)
c = np.empty(n, dtype = object)
cl = np.empty(n, dtype = object)
alp = np.empty(n, dtype = object)
a = np.empty(n, dtype = object)
rhs = np.empty(n, dtype = object)
b = np.empty(n, dtype = object)
a = np.empty(n, dtype = object)
rhs = rhs[:,None]
b = b[:,None]
a = a[:,None]
#
# Define properties at n span stations
#
pi = 4. * arctan(1.)
for i in range(0,n):
theta[i] = i * pi / (2. * n)
y[i] = span * 0.5 * cos(theta[i])
c[i] = croot + (ctip - croot) * y[i] * 2. / span
alp[i] = alpha + thetaroot - (alpha0root + (alpha0tip - alpha0root + thetaroot - thetatip) * y[i] * 2. / span)
a[i] = a0root + (a0tip - a0root) * y[i] * 2. / span
pi = 4. * arctan(1.)
# Set up 2n x 2n system of equations for A1, A3 , ... A2n-1
for j in range(0,n):
mu = c[j] * a[j] / (4. * span); print('mu=',mu)
rhs[j,0] = alp[j] * sin(theta[j]) * c[j] * a[j] / (4 * span)
for i in range(0,n):
l = 2 * i - 1
b[j,i] = sin(l * theta[j]) * (mu * l + sin(theta[j]))
然后我收到错误:
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-70-b5bd95e69bb5> in <module>()
45 for i in range(0,n):
46 l = 2 * i - 1
---> 47 b[j,i] = sin(l * theta[j]) * (mu * l + sin(theta[j]))
48
49
IndexError: index 1 is out of bounds for axis 1 with size 1
如何有效地调用这两个索引?在 MATLAB 中,b(j,i) 是正常语法。
感谢任何帮助,谢谢!
最佳答案
使用 n=10
调用 b = np.empty(n, dtype = object)
会创建一个一维数组,但您正在对其进行索引 (b[j,i]
) 就好像它是一个二维数组一样。
要初始化 10 x 10 数组,您可以调用 b = np.empty([n, n], dtype = object)
。
编辑:
我没有注意到这个作业:b = b[:,None]
这就创造了这个:
>>> [[None]
[None]
[None]
[None]
[None]
[None]
[None]
[None]
[None]
[None]]
这是一个二维数组,但尝试索引内部数组的第一个元素(仅包含 None)会导致错误。
关于python - 嵌套 FOR 循环索引问题 - Python,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27494855/