Re: [Matplotlib-users] IndexError: index out of bounds

[surfcast23 <sur...@gm...>]

I also got the dimensions of the arrays and was wandering if the problem
might be there

shape data = (101, 512) 
shape v = (512, 512) 
shape tdata = (101, 1) 
shape x = (512,)



Benjamin Root-2 wrote:
> 
> On Sun, Jul 1, 2012 at 12:50 PM, surfcast23 <sur...@gm...> wrote:
> 
>>
>> Hi,
>>   I am translating a Matlab code to python and get the following error
>> when
>> the codes reaches the plotting section
>>
>> Warning (from warnings module):
>>   File "C:\Documents and Settings\My Documents\PHYSICS\Wave-eqn.py", line
>> 40
>>     w = (D*v)
>> RuntimeWarning: overflow encountered in multiply
>> Traceback (most recent call last):
>>   File "C:\Documents and Settings\My Documents\PHYSICS\Wave-eqn\.py",
>> line
>> 50, in <module>
>>     ax.plot_wireframe(x,tdata,data, rstride=10, cstride=10)
>>   File "C:\Python32\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py",
>> line
>> 906, in plot_wireframe
>>     tylines = [tY[i] for i in cii]
>>   File "C:\Python32\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py",
>> line
>> 906, in <listcomp>
>>     tylines = [tY[i] for i in cii]
>> IndexError: index out of bounds
>>
>> My code
>>
>> import numpy as np
>> from numpy import *
>> from math import  pi
>> from scipy.linalg import toeplitz
>> from scipy.special import cotdg
>> from mpl_toolkits.mplot3d import axes3d
>> import matplotlib.pyplot as plt
>>
>>
>>
>> N = 512
>> h = 2*np.pi/N
>> x = h*(np.arange(N) + 1)
>> t = 0
>> dt = h / 4
>> a = .1
>> tmax = 15;
>> tplot = .15;
>> nplots = int(round((tmax/tplot)));
>> plotgap = int(around(tplot/dt));
>> c = a + np.sin(x - 1)**2
>> v = np.exp(-100 * (x - 1)**2)
>> vold = np.exp(-100 * (x - a*dt - 1)**2)
>>
>> #i = np.arange(1, N)
>> #column = np.hstack([0, .5 * (-1**i) * cotdg(i * h/2)])
>> #D = toeplitz(column, -column)
>>
>> column = ((0.5*(-1)**arange(1,N+1))*cotdg(arange(1,N+1))*(h/2));
>> D = toeplitz(column,-column);print(D.shape);
>>
>> k = np.zeros(((nplots,N))); print(v.shape);print(k.shape);
>> data = np.concatenate((v.reshape((512,1)).transpose(), k))#data =
>> np.concatenate((v, k),axis = 1);
>> #data = np.vstack([v,k]);
>> tdata = t;
>>
>> for i in range(1,nplots+1):
>>     for n in range(1,plotgap+1):
>>         t = t+dt
>>         w = (D*v)
>>         vnew = vold-2*dt*c*w
>>         vold = v
>>         v = vnew
>>     data[i,:] = v[0,:]
>>     tdata = vstack([tdata, t])
>>
>> fig = plt.figure()
>> ax = fig.add_subplot(111, projection='3d')
>> #X, Y, Z = axes3d.get_test_data(0.05)
>> ax.plot_wireframe(x,tdata,data, rstride=10, cstride=10)
>>
>> plt.show()
>>
>> I looked at the error line and it seems as if the y axes is where the
>> problem is, but I am not seeing why and would appreciate any help. Thank
>> you!
>>
> 
> numpy arrays are indexed starting at 0, not 1.  So when you populate your
> "data" array with "data[i,:] = v[0,:]", and "i" only goes from 1 to
> nplots,
> data[0,:] is left completely uninitialized (unless it is being done by
> some
> of your pre-for-loop code, which is confusing to understand.)
> 
> What I can tell you is that the error isn't in plot_wireframe() as much as
> the error exist with the inputs to plot_wireframe().  Perhaps the shapes
> aren't right or something.  I will try and look at your code closer
> tomorrow and see if I can figure it out, but I suggest double-checking
> those arrays.
> 
> Cheers!
> Ben Root
> 
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