[英]Finding a power spectrum in Python, without using the inbuilt FFT function
I would like to find the a power spectrum with Python using the following formula: 我想使用以下公式使用Python查找功率谱:
I am trying to plot the array that should follow from this with this: 我正在尝试绘制与此有关的数组:
P = []
for k in range(0,int(N/2)):
P.append((2/N)*(sum(x[k]*np.cos(2*np.pi*nu*t[k]))**2+(sum(x[k]*np.sin(2*np.pi*nu*t[k])))**2))
where nu are the frequencies: 其中nu是频率:
nu = []
for j in range(0, int(N/2), 2):
nu.append(j/T)
x and t come from a dataset, and N is just the total of all x. x和t来自数据集,而N只是所有x的总和。
Python keeps telling me: 'Can't multiply sequence by non-int of type 'float'' What am I doing wrong here? Python不断告诉我:“不能将序列乘以'float类型的非整数'。在这里,我在做什么错? I'm sure it's something to do with multiplying the wrong types of data with eachother.
我确定这与将错误类型的数据相互相乘有关。 But I'm not sure how to change this.
但我不确定如何更改此设置。
I know there is an inbuild FFT function, but I think it would be really instructive for me to get this function to work. 我知道有一个内置的FFT函数,但是我认为让该函数正常工作对我很有帮助。
nu is a list, so the piece of code 2*np.pi*nu*t[k]
is giving you the error.Try something like: nu是一个列表,因此代码段
2*np.pi*nu*t[k]
给您错误。尝试类似的方法:
for i in nu:
P.append((2/N)*(sum(x*np.cos(2*np.pi*nu[i]*t))**2+(sum(x*np.sin(2*np.pi*nu[i]*t)))**2))
This way you are summing the quantity (2/N)*(sum(x*np.cos(2*np.pi*nu[i]*t))**2+(sum(x*np.sin(2*np.pi*nu[i]*t)))**2)
for every i. 这样,您求和的数量为
(2/N)*(sum(x*np.cos(2*np.pi*nu[i]*t))**2+(sum(x*np.sin(2*np.pi*nu[i]*t)))**2)
对于每个i (2/N)*(sum(x*np.cos(2*np.pi*nu[i]*t))**2+(sum(x*np.sin(2*np.pi*nu[i]*t)))**2)
。
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