.. _pylab_examples-psd_demo2: pylab_examples example code: psd_demo2.py ========================================= .. plot:: /home/tcaswell/src/p/matplotlib/doc/mpl_examples/pylab_examples/psd_demo2.py :: # This example shows the effects of some of the different PSD parameters import numpy as np import matplotlib.pyplot as plt dt = np.pi / 100. fs = 1. / dt t = np.arange(0, 8, dt) y = 10. * np.sin(2 * np.pi * 4 * t) + 5. * np.sin(2 * np.pi * 4.25 * t) y = y + np.random.randn(*t.shape) # Plot the raw time series fig = plt.figure() fig.subplots_adjust(hspace=0.45, wspace=0.3) ax = fig.add_subplot(2, 1, 1) ax.plot(t, y) # Plot the PSD with different amounts of zero padding. This uses the entire # time series at once ax2 = fig.add_subplot(2, 3, 4) ax2.psd(y, NFFT=len(t), pad_to=len(t), Fs=fs) ax2.psd(y, NFFT=len(t), pad_to=len(t)*2, Fs=fs) ax2.psd(y, NFFT=len(t), pad_to=len(t)*4, Fs=fs) plt.title('zero padding') # Plot the PSD with different block sizes, Zero pad to the length of the # original data sequence. ax3 = fig.add_subplot(2, 3, 5, sharex=ax2, sharey=ax2) ax3.psd(y, NFFT=len(t), pad_to=len(t), Fs=fs) ax3.psd(y, NFFT=len(t)//2, pad_to=len(t), Fs=fs) ax3.psd(y, NFFT=len(t)//4, pad_to=len(t), Fs=fs) ax3.set_ylabel('') plt.title('block size') # Plot the PSD with different amounts of overlap between blocks ax4 = fig.add_subplot(2, 3, 6, sharex=ax2, sharey=ax2) ax4.psd(y, NFFT=len(t)//2, pad_to=len(t), noverlap=0, Fs=fs) ax4.psd(y, NFFT=len(t)//2, pad_to=len(t), noverlap=int(0.05*len(t)/2.), Fs=fs) ax4.psd(y, NFFT=len(t)//2, pad_to=len(t), noverlap=int(0.2*len(t)/2.), Fs=fs) ax4.set_ylabel('') plt.title('overlap') plt.show() Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)