code: def plotSpectrumComparison(signals, signalkey, speaks, spectrum):
      fig = figure(figsize=(8, 5), dpi=80)
      for skey in signalkey:
          signal = signals[skey]
          pfreq, pmagn = speaks(spectrum(signal))
          plot(pfreq * fs / 2, pmagn)
      legend(signalkey)
      title = "Spectrum BPF of WN"
      fig.suptitle(title)
      figname = title + ".png"
      fig.savefig(figname)
      close("all")
      html_ = '<p><img src="' + figname + '"></p>\n'
      return html_
  
file_path: essentia/test/src/qa/hpcp/test_hpcp_plots.py
imports: import numpy
  import essentia
  from essentia.standard import *
  from matplotlib.pyplot import imshow, show, plot, title, ylim, legend, figure, grid, GridSpec, subplot, text, tight_layout, yticks, locator_params, close
  import matplotlib.pyplot
  from test_hpcp_parameters import *
  from test_hpcp_extract import *
label_desc: Use image node_id 2 for calling a global function with example usage: plotSpectrumComparison(signals, signalkey, speaks, spectrum) and returns: html_