我将一些matlab代码转换为python代码并调试了这两个代码,但从调用cumtrapz函数得到的结果却有所不同,我还验证了两者的输入数据是否相似。这是代码:

Python代码

from numpy import zeros, ceil, array, mean, ptp, abs, sqrt, power
from scipy.integrate import cumtrapz

def step_length_vector(ics_y, fcs_y, acc_y, l, sf):
    step_length_m1 = zeros(int(ceil(len(ics_y)/2))-1)

    for i in range(0, len(ics_y)-2, 2):
        av = acc_y[int(ics_y[i]):int(ics_y[i+2])+1]
        t = array(range(1, int((ics_y[i+2]-ics_y[i])+2)))/sf
        hvel = cumtrapz(t, av - mean(av), initial=0)
        h = cumtrapz(t, hvel - mean(hvel), initial=0)
        hend = ptp(h)
        sl = 6.8*(sqrt(abs(2*l*hend - hend**2)))
        step_length_m1[int(ceil(i/2))] = sl

    return step_length_m1


Matlab代码

function [StepLengthM1] = StepLengthVector(ICsY,FCsY,ACCY,l,sf)

        StepLengthM1 = zeros(1,ceil(length(ICsY)/2)-1);

        for i= 1:2:length(ICsY)-2
           av   = ACCY(ICsY(i):ICsY(i+2));
           t    = (1:(ICsY(i+2)-ICsY(i))+1)/sf;
           hvel = cumtrapz(t,av-mean(av));
           h    = cumtrapz(t,hvel-mean(hvel));
           hend = peak2peak(h);
           sl   = 6.8*(sqrt(abs(2*l*hend - hend.^2)));
           StepLengthM1(ceil(i/2)) = sl;
        end
end


两个代码的hvel变量不同。也许我使用错误的scipy cumtrapz是因为我假设接收的initial值为0。在这两种情况下,输入ics_y(ICsy)fcs_y(FCsY),acc_y (ACCY)是一维数组,而lsf是标量。

谢谢!!!

最佳答案

(如果这个问题是关于cumtrapz的,则应将测试简化为仅调用一次cumtrapz,并在matlab和Python中使用相同的输入数组。此外,请确保您仔细阅读了每个函数的matlab和SciPy文档。 SciPy函数通常不是相应matlab函数的精确副本。)

问题在于,当您同时给出xy值时,在matlab / octave中给出的顺序为x, y,但在SciPy版本中为y, x

例如,

octave:11> t = [0 1 1.5 4 4.5 6]
t =

   0.00000   1.00000   1.50000   4.00000   4.50000   6.00000

octave:12> y = [1 2 3 -2 0 1]
y =

   1   2   3  -2   0   1

octave:13> cumtrapz(t, y)
ans =

   0.00000   1.50000   2.75000   4.00000   3.50000   4.25000


要使用scipy.integrate.cumtrapz获得相同的结果:

In [22]: from scipy.integrate import cumtrapz

In [23]: t = np.array([0, 1, 1.5, 4, 4.5, 6])

In [24]: y = np.array([1, 2, 3, -2, 0, 1])

In [25]: cumtrapz(y, t, initial=0)
Out[25]: array([0.  , 1.5 , 2.75, 4.  , 3.5 , 4.25])

关于python - Matlab cumtrapz和scipy.integrate cumtrapz的不同结果,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/56974699/

10-10 18:27