How can I convert Arduino signal from Python to Fast Fourier transform? - matplotlib

Question

I'm now trying to convert the signal into a Fast Fourier transform in Python and draw a graph. I have a problem with Len here. How can I fix this? And does anyone have any other ideas about converting Fast Fourier transform?
Exception has occurred: TypeError
object of type 'method' has no len()
That is my problem.
from PyQt5.QtWidgets import*
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import matplotlib.pyplot as plt
import random
from PyQt5 import QtCore, QtGui, QtWidgets
import datetime
import serial
import time
import random
import numpy as np
from matplotlib import animation
from collections import deque
import threading
x = 0
value = [0]
ser = serial.Serial('com5', 9600)
class scope :
def data(self) :
if ser.readable() :
time.sleep(0.01)
reciving = ser.readline(ser.inWaiting())
str = reciving.decode()
if len(str) > 0 :
if str[:1] == 'X' :
value[0] = str[1:]
#print(float(value[5]))
time.sleep(0.5)
x = float(value[0])
return x
s = scope()
n = len(s.data)
Ts = 0.01
Fs = 1/Ts
# length of the signal
k = np.arange(n)
T = n/Fs
freq = k/T # two sides frequency range
freq = freq[range(int(n/2))] # one side frequency range
Y = np.fft.fft(x)/n # fft computing and normalization
Y = Y[range(int(n/2))]
fig, ax = plt.subplots(2, 1)
ax.plot(freq, abs(Y), 'r', linestyle=' ', marker='^')
ax.set_xlabel('Freq (Hz)')
ax.set_ylabel('|Y(freq)|')
#3ax.vlines(freq, [0], abs(Y))
ax.grid(True)
t = threading.Thread(target= s.data)
t.daemon = True
t.start()
plt.show()