Test Engineers Resource

# -*- coding: utf-8 -*-
"""
Created on Tue Oct 31 06:38:35 2023

@author: aleja
"""
#MODIFIED For use by LabVIEW (see previous blog for python only)
#Testing out code form Bing Chat as starting point
#some modification added for clarity,and testing

# Generate some sample data
import numpy as np
#import matplotlib.pyplot as plt

N = 20 # number of data points
amp = 2.0 # amplitude of the sinewave
freq = 0.2 # frequency of the sinewave
phase = np.pi / 4 # phase of the sinewave
offset = 1.0 # offset of the sinewave
noise = 0.01 # noise level  reduce from chat was 0.5 to see lest noise at first

def MakeSineWaveData(amp,freq,phase,offset,N,noise):
    #number of cycle freq * max x
    # Create the x and y values
    x = np.linspace(0,10, N)  #changing this to test how strong this leastsq fit is
    y = amp * np.sin(2 * np.pi * freq * x + phase) + offset
    y += noise * np.random.randn(N) # add some noise
    print("===x===")
    #print(x)
    print(np.array2string(x, separator=',',formatter={'float_kind':lambda x: "%.3f" % x}))
    print("===End===")
    #print(y)
    print("===y===")
    print(np.array2string(y, separator=',',formatter={'float_kind':lambda x: "%.3f" % x}))
    print("===End===")    
    return x,y

# #Test function here
#x,y=MakeSineWaveData(amp,freq,phase,offset,N,noise)
# # Plot the data
# plt.scatter(x, y)
# plt.xlabel("x-voltage")
# plt.ylabel("y-optical detector")
# plt.title("Sample data-fictional")
# plt.show()


#Next Fit testing out chat code
# Fit a sinewave using least squares optimization
from scipy.optimize import leastsq

# Define the sinewave function
def sin_func(p, x):
    A, f, p, c = p # unpack the parameters
    return A * np.sin(2 * np.pi * f * x + p) + c

# Define the error function to minimize
def error_func(p, x, y):
    return y - sin_func(p, x)

# Make some initial guesses for the parameters
p0 = [amp, freq, phase, offset]

def GetSinewaveFitParameters(error_func,p0,x,y):
# Optimize the parameters using least squares
    p_opt, p_cov = leastsq(error_func, p0, args=(x,y))
    return p_opt,p_cov

# #test function here
# p_opt,p_cov=GetSinewaveFitParameters(error_func,p0,x,y)

# X = np.linspace(0, 10, N*10) #new x for better visual of sinewave
# # Predict the y values using the optimized parameters
# y_pred = sin_func(p_opt,X)

# # Plot the inputdata(blue dots) and predicted curves(red line)
# plt.plot(x,y,"b.",label="data")

# plt.plot(X,y_pred,"r-",label="prediction")
# plt.xlabel("x-voltage")
# plt.ylabel("y-optical detector")
# plt.title("Sinewave fitting using least squares-not real product data")
# plt.legend()
# plt.show()

def Print_Sinewave_Info(amp,freq,phase,offset,N,x,y,p_opt,p_cov):
    #added print for simulation info
    #print will go to console (spyder or Labview stdout)
    print("===Simulated Paramters:===") #===section=== format need for LV extraction
    print(f"Number of Points: {N}")
    print(f"Number of cycles {freq*np.max(x):.1f}")
    print(f"Amplitude: {amp:.3f}")
    print(f"Frequency: {freq:.3f}")
    print(f"Phase: {phase:.3f}")
    print(f"Offset: {offset:.3f}")
    print(f"Noise: {noise:.3f}")
    print("===End===")
    print("\n")
    # Print the optimized parameters
    print("===Fit Parameters:===")
    print(f"Amplitude: {p_opt[0]:.3f}")
    print(f"Frequency: {p_opt[1]:.3f}")
    print(f"Phase: {p_opt[2]:.3f}")
    print(f"Offset: {p_opt[3]:.3f}")
    print("===End===")
    print("\n")
# #Test out function
#Print_Sinewave_Info(amp,freq,phase,offset,N,x,y,p_opt,p_cov)


#added comments below not part of Chat info
#summary: Chat created code was workable, added print to compare sim and fit
#opinion: does a good job at fitting sinewave ...see presentation
#opinion: best when provide with more points over cycle (most know this)
#see blog presentation at www.testengineerresource.com
#Environment used: python 3.11.3 and worked in Spyder IDE 5.4.3 (conda), mathplotlib 3.7.1
#Environment info: I have plot show in own window (not in Spyder)
#Plots are not clear to allow for testing of overlap sinewave fit.

#getting version info
#import matplotlib
#print ('matplotlib: {}'.format (matplotlib.__version__))