old_contents: # #!/usr/bin python
  #Test Noise Addition:
  
  import numpy as np
  import matplotlib.pyplot as plt
  
  
  def add_noise(flux, SNR):
      "Using the formulation mu/sigma"
      mu = np.mean(flux)
      sigma = mu / SNR
      # Add normal distributed noise at the SNR level.
      noisey_flux = flux + np.random.normal(0, sigma, len(flux))
      return noisey_flux
  
  
  def main():
      """ Visually test the addition of Noise using add_noise function
      """
      flux = np.ones(100)
      for i, snr in enumerate([50, 100, 200, 300]):
          plt.plot(add_noise(flux, snr) + 0.05 * i, label="snr={}".format(snr))
      plt.legend()
      plt.show()
  
  
  if __name__ == "__main__":
      main()
  
new_contents: #!/usr/bin/env python
  #Test Noise Addition:
  
  import numpy as np
  import matplotlib.pyplot as plt
  
  
  def add_noise(flux, SNR):
      "Using the formulation mu/sigma"
      mu = np.mean(flux)
      sigma = mu / SNR
      # Add normal distributed noise at the SNR level.
      noisey_flux = flux + np.random.normal(0, sigma, len(flux))
      return noisey_flux
  
  
  def add_noise2(flux, SNR):
      "Using the formulation mu/sigma"
      #mu = np.mean(flux)
      sigma = flux / SNR
      # Add normal distributed noise at the SNR level.
      noisey_flux = flux + np.random.normal(0, sigma)
      return noisey_flux
  
  
  def main():
      """ Visually test the addition of Noise using add_noise function
      """
      flux = np.ones(100)
      for i, snr in enumerate([50, 100, 200, 300]):
          # Test that the standard deviation of the noise is close to the snr level
          print("Applying a snr of {}".format(snr))
          noisey_flux = add_noise(flux, snr)
          std = np.std(noisey_flux)
          print("Standard deviation of signal = {}".format(std))
          SNR = 1 / std
          print("Estimated SNR from stddev = {}".format(SNR))
          plt.plot(noisey_flux + 0.05 * i, label="snr={}".format(snr))
  
      plt.legend()
      plt.show()
  
  
  
  
  
  
  
  
  if __name__ == "__main__":
      main()
  
subject: Fix noise calculation, add printing to check SNR value of data