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

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

Hi Ben,

  I was working on some other things and have finally gotten a chance to get
back to this. I changed the for loops to

for i in range(nplots):
    for n in range(plotgap):
        t = t+dt
        w = (D*v)
        vnew = vold-2*dt*c*w
        vold = v
        v = vnew
    data[i,:] = v[0,:]
    tdata = vstack([tdata, t])    

But I still get the same error as in my original post.

Khary


surfcast23 wrote:
> 
> I will try initializing starting at 0
> 
> 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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>> 
> 
> 

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