Plotters

Collection of plotters

xaratustrah@github 2017

plot_frame_power(yy, frame_power)

Plot frame power, i.e. trapezoid along each time frame

Parameters:

Name	Type	Description	Default
yy	ndarray	Time meshgrid	required
frame_power	ndarray	Array describing the frame power	required

Source code in iqtools/plotters.py

def plot_frame_power(yy, frame_power):
    """Plot frame power, i.e. trapezoid along each time frame

    Args:
        yy (ndarray): Time meshgrid
        frame_power (ndarray): Array describing the frame power
    """    
    plt.plot(yy[:, 0], IQBase.get_dbm(frame_power))
    plt.ylabel('Power [dBm]')
    plt.xlabel('Time [sec]')
    plt.title('Frame power')

plot_hilbert(x_bar)

Shows the Hilbert plot

Parameters:

Name	Type	Description	Default
x_bar	ndarray	Complex valued data array	required

Source code in iqtools/plotters.py

def plot_hilbert(x_bar):
    """Shows the Hilbert plot

    Args:
        x_bar (ndarray): Complex valued data array
    """    

    plt.plot(np.real(x_bar), np.imag(x_bar))
    plt.grid(True)
    plt.xlabel('Real Part')
    plt.ylabel('Imag. Part')

plot_phase_shift(x, phase)

Plots the signal before and after the phase shift

Parameters:

Name	Type	Description	Default
x	ndarray	Data array	required
phase	float	Phase shift	required

Source code in iqtools/plotters.py

def plot_phase_shift(x, phase):
    """Plots the signal before and after the phase shift

    Args:
        x (ndarray): Data array
        phase (float): Phase shift
    """    
    plt.rcParams['axes.grid'] = True
    fig, axs = plt.subplots(2, 2, sharex=True, sharey=True)
    axs[0, 0].plot(np.real(x))
    axs[0, 1].plot(np.imag(x))
    axs[1, 0].plot(np.real(shift_phase(x, phase)))
    axs[1, 1].plot(np.imag(shift_phase(x, phase)))

plot_spectrogram(xx, yy, zz, cen=0.0, cmap=cm.jet, dpi=300, dbm=False, filename=None, title='Spectrogram', zzmin=0, zzmax=1000000.0, mask=False, span=None, decimal_place=2)

Plot the calculated spectrogram. For the coordinates, it also accepts sparse matrices.

Parameters:

Name	Type	Description	Default
xx	ndarray	Frequency meshgrid, can be sparse	required
yy	ndarray	Time meshgrid, can be sparse	required
zz	ndarray	Power meshgrid	required
cen	float	Center frequency. Defaults to 0.0.	0.0
cmap	string	Matplotlib.colormap. Defaults to cm.jet.	jet
dpi	int	Resolution for PNG output. Defaults to 300.	300
dbm	bool	Display in dBm scale. Defaults to False.	False
filename	str	File name. Defaults to None, in which case nothing will be saved to file.	None
title	str	Title of the plot. Defaults to 'Spectrogram'.	'Spectrogram'
zzmin	int	Color contrast min. Defaults to 0.	0
zzmax	int	Color contrast max. Defaults to 1e6.	1000000.0
mask	bool	Mask out values less than this, for cleaner histograms. Defaults to False.	False
span	float	Show only a frequency window. Defaults to None.	None
decimal_place	int	Limit display of decimal places of all numbers in the plot. Defaults to 2.	2

Source code in iqtools/plotters.py

def plot_spectrogram(xx, yy, zz, cen=0.0, cmap=cm.jet, dpi=300, dbm=False, filename=None, title='Spectrogram', zzmin=0, zzmax=1e6, mask=False, span=None, decimal_place=2):
    """Plot the calculated spectrogram. For the coordinates, it also accepts sparse matrices.


    Args:
        xx (ndarray): Frequency meshgrid, can be sparse
        yy (ndarray): Time meshgrid, can be sparse
        zz (ndarray): Power meshgrid
        cen (float, optional): Center frequency. Defaults to 0.0.
        cmap (string, optional): Matplotlib.colormap. Defaults to cm.jet.
        dpi (int, optional): Resolution for PNG output. Defaults to 300.
        dbm (bool, optional): Display in dBm scale. Defaults to False.
        filename (str, optional): File name. Defaults to None, in which case nothing will be saved to file.
        title (str, optional): Title of the plot. Defaults to 'Spectrogram'.
        zzmin (int, optional): Color contrast min. Defaults to 0.
        zzmax (int, optional): Color contrast max. Defaults to 1e6.
        mask (bool, optional): Mask out values less than this, for cleaner histograms. Defaults to False.
        span (float, optional): Show only a frequency window. Defaults to None.
        decimal_place (int, optional): Limit display of decimal places of all numbers in the plot. Defaults to 2.
    """    
    # Apply display threshold if zmin and zmax are provided, they must be different than the default values of 0 and 1e6
    # otherwise ignore them

    if zzmin >= 0 and zzmax <= 1e6 and zzmin < zzmax:
        zz = zz / np.max(zz) * 1e6
        mynorm = Normalize(vmin=zzmin, vmax=zzmax)

        # mask arrays for transparency in pcolormesh
        if mask:
            zz = np.ma.masked_less_equal(zz, zzmin)

    else:
        # pcolormesh ignores if norm is None
        mynorm = None

    if dbm:
        zz = IQBase.get_dbm(zz)

    # here comes span in [Hz]
    if not span:
        spanmask = (xx[0, :] != 0) | (xx[0, :] == 0)
    else:
        spanmask = (xx[0, :] <= span / 2) & (xx[0, :] >= -span / 2)
    xx = xx[:, spanmask]
    zz = zz[:, spanmask]
    # we have to check yy before, make sure it is sparse or not
    yy = yy[:,spanmask] if np.shape(yy)[1] > 1 else yy

    # here comes the plot
    sp = plt.pcolormesh(xx, yy, zz, cmap=cmap,  shading='auto')

    # here is the color bar
    cb = plt.colorbar(sp, format=f'%.{decimal_place}e')

    ax = plt.gca()
    ax.xaxis.set_major_formatter(FormatStrFormatter(f'%.{decimal_place}e'))

    delta_f = np.abs(np.abs(xx[0, 1]) - np.abs(xx[0, 0]))
    delta_t = np.abs(np.abs(yy[1, 0]) - np.abs(yy[0, 0]))

    plt.xlabel(
        "Delta f [Hz] @ {} (resolution = {})".format(get_eng_notation(cen, unit='Hz', decimal_place=decimal_place), get_eng_notation(delta_f, unit='Hz', decimal_place=decimal_place)))
    plt.ylabel('Time [sec] (resolution = {})'.format(
        get_eng_notation(delta_t, 's', decimal_place=decimal_place)))
    plt.title(title)

    if dbm:
        cb.set_label('Power Spectral Density a.u. [dBm/Hz]')
    else:
        cb.set_label('Power Spectral Density a.u.')

    if filename is not None:
        plt.savefig(filename + '.png', dpi=dpi, bbox_inches='tight')
        plt.close()

plot_spectrogram_with_gnuplot(zz)

Plots using external instance of GNUPlot. Data is reshaped in form of a matrix for plotting. Idea based on this post on SO

Parameters:

Name	Type	Description	Default
zz	ndarray	Power meshgrid	required

Source code in iqtools/plotters.py

def plot_spectrogram_with_gnuplot(zz):
    """Plots using external instance of [GNUPlot](http://www.gnuplot.info/). Data is reshaped in form of a matrix for plotting. Idea based on [this post on SO](https://stackoverflow.com/a/15885230/5177935)

    Args:
        zz (ndarray): Power meshgrid
    """    
    temp_file = 'foo.bin'
    with open(temp_file, 'wb') as foo:
        for (i, j), dat in np.ndenumerate(np.rot90(zz, 3)):
            s = struct.pack('4f', i, j, dat, dat)
            foo.write(s)

    gnuplot = subprocess.Popen(
        ['gnuplot'], stdin=subprocess.PIPE, universal_newlines=True)

    gnuplot.stdin.write("""
    set pm3d map;
    unset clabel;
    set terminal png size 1024,768;
    set palette defined (0 0.0 0.0 0.5, \
                         1 0.0 0.0 1.0, \
                         2 0.0 0.5 1.0, \
                         3 0.0 1.0 1.0, \
                         4 0.5 1.0 0.5, \
                         5 1.0 1.0 0.0, \
                         6 1.0 0.5 0.0, \
                         7 1.0 0.0 0.0, \
                         8 0.5 0.0 0.0 );
    """)
    gnuplot.stdin.write("set output '{}.png';".format(temp_file))
    gnuplot.stdin.write(
        "splot '{}' binary record=(10,-1) format='%float' u 1:2:3:4 w pm3d;".format(temp_file))

plot_spectrum(f, p, cen=0.0, span=None, dbm=False, filename=None, title='Spectrum')

Plots 2D spectrum in dBm per Hz

Parameters:

Name	Type	Description	Default
f	ndarray	Frequency array	required
p	ndarray	Power array	required
cen	float	Center frequency. Defaults to 0.0.	0.0
span	float	Frequency window. Defaults to None.	None
dbm	bool	Display in dBm scale. Defaults to False.	False
filename	str	File name. Defaults to None, in which case nothing will be saved to file.	None
title	str	Title of the plot. Defaults to 'Spectrogram'.	'Spectrum'

Source code in iqtools/plotters.py

def plot_spectrum(f, p, cen=0.0, span=None, dbm=False, filename=None, title='Spectrum'):
    """Plots 2D spectrum in dBm per Hz

    Args:
        f (ndarray): Frequency array
        p (ndarray): Power array
        cen (float, optional): Center frequency. Defaults to 0.0.
        span (float, optional): Frequency window. Defaults to None.
        dbm (bool, optional): Display in dBm scale. Defaults to False.
        filename (str, optional): File name. Defaults to None, in which case nothing will be saved to file.
        title (str, optional): Title of the plot. Defaults to 'Spectrogram'.
    """    

    if not span:
        spanmask = (f != 0) | (f == 0)
    else:
        spanmask = (f <= span / 2) & (f >= -span / 2)
    if dbm:
        plt.plot(f[spanmask], IQBase.get_dbm(p[spanmask]))
    else:
        plt.plot(f[spanmask], p[spanmask])

    ax = plt.gca()
    ax.xaxis.set_major_formatter(FormatStrFormatter('%.0e'))

    plt.xlabel("Delta f [Hz] @ {}".format(get_eng_notation(cen, 'Hz')))
    plt.title(title)
    if dbm:
        plt.ylabel('Power Spectral Density [dBm/Hz]')
    else:
        plt.ylabel('Power Spectral Density')

    plt.grid(True)
    if filename is not None:
        plt.savefig(filename + '.png')  # , bbox_inches='tight')
        plt.close()