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matplotlib.pyplot.angle_spectrum() in Python

  • Last Updated : 12 Apr, 2020

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. Pyplot is a state-based interface to a Matplotlib module which provides a MATLAB-like interface.

matplotlib.pyplot.acorr() Function:

The angle_spectrum() function in pyplot module of matplotlib library is used to plot the angle spectrum. Generally, it computes the angle spectrum of sequence and plotting is done.

Syntax: angle_spectrum(x, Fs=2, Fc=0, window=mlab.window_hanning, pad_to=None, sides=’default’, **kwargs)

Parameters: This method accept the following parameters that are described below:

  • x: This parameter is a sequence of data.
  • Fs : This parameter is a scalar. Its default value is 2.
  • window: This parameter take a data segment as an argument and return the windowed version of the segment. Its default value is window_hanning()
  • sides: This parameter specifies which sides of the spectrum to return. This can have following values : ‘default’, ‘onesided’ and ‘twosided’.
  • pad_to : This parameter contains the integer value to which the data segment is padded.
  • Fc: This parameter is also contains the integer value to offsets the x extents of the plot to reflect the frequency range. Its default value is 0

Returns: This returns the following:

  • spectrum :This returns the angle spectrum in radians.
  • freqs :This returns the frequencies corresponding to the elements in spectrum.
  • line : This returns the line created by this function.

The resultant is (spectrum, freqs, line)

Below examples illustrate the matplotlib.pyplot.angle_spectrum() function in matplotlib.pyplot:

Example #1:




# Implementation of matplotlib.pyplot.angle_spectrum()
# function
  
import matplotlib.pyplot as plt
import numpy as np
  
np.random.seed(10**5)
  
dt = 0.0001
Fs = 1 / dt
geeks = np.array([24.40, 110.25, 20.05
                  22.00, 61.90, 7.80
                  15.00, 22.80, 34.90
                  57.30])
  
nse = np.random.randn(len(geeks))
r = np.exp(-geeks / 0.05)
  
s = 0.1 * np.sin(2 * np.pi * geeks) + nse
  
# plot angle_spectrum
plt.angle_spectrum(s, Fs = Fs)
  
# Display the simple spectrum and 
# angle_spectrum plot
plt.show()

Output:

Example #2:




# Implementation of matplotlib.pyplot.angle_spectrum()
# function
  
import matplotlib.pyplot as plt
import numpy as np
  
np.random.seed(0)
  
dt = 0.01
Fs = 1 / dt
t = np.arange(0, 10, dt)
nse = np.random.randn(len(t))
r = np.exp(-t / 0.05)
  
cnse = np.convolve(nse, r)*dt
cnse = cnse[:len(t)]
s = 0.1 * np.sin(2 * np.pi * t) + cnse
  
# plot simple spectrum
plt.subplot(2, 1, 1)
plt.plot(t, s)
  
# plot angle_spectrum
plt.subplot(2, 1, 2)
plt.angle_spectrum(s, Fs = Fs)
  
# Display the simple spectrum and 
# angle_spectrum plot
plt.show()

Output:


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