From 373164f1b0ff98aad0ce91668664adb3045a4287 Mon Sep 17 00:00:00 2001 From: Eric Teunis de Boone Date: Tue, 14 Nov 2023 16:24:57 +0100 Subject: [PATCH] Lib: functions to easily plot FT's --- lib/ft_plot.py | 217 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 217 insertions(+) create mode 100644 lib/ft_plot.py diff --git a/lib/ft_plot.py b/lib/ft_plot.py new file mode 100644 index 0000000..6b15db1 --- /dev/null +++ b/lib/ft_plot.py @@ -0,0 +1,217 @@ +""" +Functions to simplify plotting of fourier spectra +""" +# vim: fdm=indent ts=4 + +import matplotlib.pyplot as plt +import matplotlib.gridspec as gridspec +import numpy as np + +def plot_amplitude(*args, **kwargs): + kwargs = { 'plot_amplitude': True, **kwargs} + return plot_spectrum(*args, **kwargs) + +def plot_spectrum( + spectrum, freqs, + plot_complex=False, plot_power=False, plot_amplitude=None, + freq_unit="Hz", freq_scaler=1, + title='Spectrum', xlabel='Frequency', ax=None, + ylabel=True, grid=True, + **plot_kwargs + ): + """ Plot a signal's spectrum on an Axis object""" + plot_amplitude = plot_amplitude or (not plot_power and not plot_complex) + alpha = 1 + + if ax is None: + ax = plt.gca() + + if title: + ax.set_title(title) + if xlabel: + ax.set_xlabel(xlabel + (" ["+freq_unit+"]" if freq_unit else "" )) + if ylabel is True: + ylabel = "" + if plot_amplitude or plot_complex: + ylabel = "Amplitude" + if plot_power: + if ylabel: + ylabel += "|" + ylabel += "Power" + if ylabel: + ax.set_ylabel(ylabel) + + ax.grid(grid) + + plot_kwargs = {'marker': '.', 'linestyle': 'solid', **plot_kwargs} + if plot_complex: + alpha = 0.5 + ax.plot(freqs/freq_scaler, np.real(spectrum), **{**dict(label='Real', alpha=alpha, ), **plot_kwargs}) + ax.plot(freqs/freq_scaler, np.imag(spectrum), **{**dict(label='Imag', alpha=alpha, ), **plot_kwargs}) + + if plot_power: + ax.plot(freqs/freq_scaler, np.abs(spectrum)**2, **{**dict(label='Power', alpha=alpha,), **plot_kwargs}) + + if plot_amplitude: + ax.plot(freqs/freq_scaler, np.abs(spectrum), **{**dict(label='Abs', alpha=alpha, ), **plot_kwargs}) + + ax.legend() + + return ax + +def plot_phase( + spectrum, freqs, + ylim_epsilon=0.5, ax=None, grid=True, + freq_unit="Hz", freq_scaler=1, xlabel='Frequency', + ylabel="Phase", + major_divider=2, minor_divider=12, + **plot_kwargs + ): + """ + Plot the phase of spectrum + """ + + if ax is None: + ax = plt.gca() + + if ylabel: + ax.set_ylabel("Phase") + if xlabel: + ax.set_xlabel(xlabel + (" ["+freq_unit+"]" if freq_unit else "" )) + + ax.grid(grid) + + plot_kwargs = {'marker': '.', 'linestyle': 'solid', **plot_kwargs} + ax.plot(freqs/freq_scaler, np.angle(spectrum), **plot_kwargs) + ax.set_ylim(-1*np.pi - ylim_epsilon, np.pi + ylim_epsilon) + + axis_pi_ticker(ax.yaxis, major_divider=major_divider, minor_divider=minor_divider) + + return ax + +def axis_pi_ticker(axis, major_divider=2, minor_divider=12): + + major_tick = Multiple(major_divider, np.pi, '\pi') + minor_tick = Multiple(minor_divider, np.pi, '\pi') + + axis.set_major_locator(major_tick.locator()) + axis.set_major_formatter(major_tick.formatter()) + axis.set_minor_locator(minor_tick.locator()) + + return axis + +def plot_signal( + signal, sample_rate = 1, + time=None, ax=None, + title='Signal', ylabel='Amplitude', + time_unit="s", xlabel='Time', + **kwargs): + """ + Plot the signal in the time domain + """ + + if ax is None: + ax = plt.gca() + + if time is None: + time = np.arange(len(signal))/sample_rate + + if title: + ax.set_title(title) + if xlabel: + ax.set_xlabel(xlabel + (" ["+time_unit+"]" if time_unit else "" )) + if ylabel: + ax.set_ylabel(ylabel) + + ax.plot(time, signal, **kwargs) + + return ax + +def combined_spectrum_figure( + spectrum, freqs, + fig=None, gs=None, + spectrum_ax=None, phase_ax=None, + spectrum_kwargs={}, phase_kwargs={}, + **shared_kwargs + ): + """ + Plot both the frequencies and phase in one figure. + """ + + ax1, ax2 = None, None + if spectrum_ax is not None or phase_ax is not None: + if spectrum_ax is not None: + ax1 = spectrum_ax + if phase_ax is not None: + ax2 = phase_ax + + else: + # configure plotting layout + if fig is None: + fig = plt.figure() + + if gs is None: + gs = gridspec.GridSpec(2, 1, figure=fig, height_ratios=[3,1], hspace=0) + + ax1 = fig.add_subplot(gs[:-1, -1]) + ax2 = fig.add_subplot(gs[-1, -1], sharex=ax1) + + axes = np.array([ax1, ax2]) + + # plot the spectrum + plot_spectrum(spectrum, freqs, ax=ax1, **{ **shared_kwargs, **spectrum_kwargs}) + + # plot the phase + plot_phase(spectrum, freqs, ax=ax2, **{ **shared_kwargs, **phase_kwargs}) + + ax1.xaxis.tick_top() + [label.set_visible(False) for label in ax1.get_xticklabels()] + + return fig + +def multiple_formatter(denominator=2, number=np.pi, latex='\pi'): + """ + From https://stackoverflow.com/a/53586826 + """ + def gcd(a, b): + while b: + a, b = b, a%b + return a + + def _multiple_formatter(x, pos): + den = denominator + num = np.int(np.rint(den*x/number)) + com = gcd(num,den) + (num,den) = (int(num/com),int(den/com)) + if den==1: + if num==0: + return r'$0$' + if num==1: + return r'$%s$'%latex + elif num==-1: + return r'$-%s$'%latex + else: + return r'$%s%s$'%(num,latex) + else: + if num==1: + return r'$\frac{%s}{%s}$'%(latex,den) + elif num==-1: + return r'$\frac{-%s}{%s}$'%(latex,den) + else: + return r'$\frac{%s%s}{%s}$'%(num,latex,den) + return _multiple_formatter + +class Multiple: + """ + From https://stackoverflow.com/a/53586826 + """ + def __init__(self, denominator=2, number=np.pi, latex='\pi'): + self.denominator = denominator + self.number = number + self.latex = latex + + def locator(self): + return plt.MultipleLocator(self.number / self.denominator) + + def formatter(self): + return plt.FuncFormatter(multiple_formatter(self.denominator, self.number, self.latex))