pyyeti.dsp.calcenv

pyyeti.dsp.calcenv(x, y, p=5, n=2000, method='max', base=0.0, makeplot='clear', polycolor=(1, 0.7, 0.7), label='data')

Returns a curve that envelopes the y data that is allowed to shift in the x-direction by some percentage. Optionally plots original curve with shaded enveloping polygon.

Parameters:

• x (array_like) – x-axis data vector; must be monotonically ascending

• y (array_like) – y-axis data vector; must be same length as x

• p (scalar; optional) – Percentage to shift the y data left and right

• n (integer; optional) – Number of points to use for enveloping curve

• method (string; optional) – Specifies how to envelop data:

  method	Description
  ‘max’	compute envelope over the maximum values of y
  ‘min’	compute envelope over the minimum values of y
  ‘both’	combine both ‘max’ and ‘min’

• base (scalar or None; optional) – The base y-value (defines one side of the envelope); if None, no base y-value is used and method is automatically set to ‘both’

• makeplot (string or axes object; optional) – Specifies if and how to plot envelope in current figure:

  makeplot	Description
  ‘no’	do not plot
  ‘clear’	plot after clearing figure
  ‘add’	plot without clearing figure
  ‘new’	plot in new figure
  axes object	plot in given axes (like ‘add’)

• polycolor (color specification; optional) – Any valid matplotlib color specification for the color of the enveloping curve

• label (string; optional) – Label for the x-y data on plot (only used if makeplot is not ‘no’)

Returns:

• xe_max (1d ndarray) – x-axis data vector for enveloping curve on max side

• ye_max (1d ndarray) – y-axis data vector for enveloping curve on max side

• xe_min (1d ndarray) – x-axis data vector for enveloping curve on min side

• ye_min (1d ndarray) – y-axis data vector for enveloping curve on min side

• h (None or list) – If makeplot is not ‘no’, h is a 2-element list of graphic handles: [line, patch].

Examples

>>> import numpy as np
>>> import matplotlib.pyplot as plt
>>> from pyyeti import dsp
>>> x = np.arange(1.0, 31.0, 1.0)
>>> y = np.cos(x)
>>> fig = plt.figure('Example', figsize=[10, 8], clear=True,
...                  layout='constrained')
>>>
>>> ax = plt.subplot(411)
>>> env = dsp.calcenv(x, y, base=None, makeplot='add')
>>> _ = plt.title('base=None (method="both")')
>>> _ = ax.legend(handles=env[-1], loc='upper left',
...               bbox_to_anchor=(1.02, 1.),
...               borderaxespad=0.)
>>> _ = ax.set_xticklabels([])
>>>
>>> ax = plt.subplot(412)
>>> env = dsp.calcenv(x, y, method='both', makeplot='add')
>>> _ = plt.title('method="both"')
>>> ax.legend().set_visible(False)
>>> _ = ax.set_xticklabels([])
>>>
>>> ax = plt.subplot(413)
>>> env = dsp.calcenv(x, y, method='max', makeplot='add')
>>> _ = plt.title('method="max"')
>>> ax.legend().set_visible(False)
>>> _ = ax.set_xticklabels([])
>>>
>>> ax = plt.subplot(414)
>>> env = dsp.calcenv(x, y, method='min', makeplot='add')
>>> _ = plt.title('method="min"')
>>> ax.legend().set_visible(False)