Power Spectra Example

Example of a power spectra plot.

Saving figures to memory, n_iterations: 7

from gerg_plotting import ScatterPlot, data_from_df
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

# Let's read in the example data
df = pd.read_csv('example_data/sample_tabs_data.csv')

# Init some base parameters
samp_freq = 48
seg_len = 256
theta_rad = np.deg2rad(55)
highlight_freqs = [1/10, 1, 2]
y_limits = (10,10e5)

# In this first example we will let the power_spectra_density function calculate the PSD for us,
# we just need to supply a few parameters to the calculation

# Init data
data = data_from_df(df)
# Init ScatterPlot
scatter = ScatterPlot(data)
# Plot power spectra density
scatter.power_spectra_density(var_name='u',sampling_freq=samp_freq,segment_length=seg_len,theta_rad=theta_rad,
                                highlight_freqs=highlight_freqs)
# Set the ylimits so the plots all match up
scatter.ax.set_ylim(*y_limits)
# Add an informative title
scatter.ax.set_title('Vector U')
# scatter.show()

# Now Let's look at a more advanced use

# Import the Animator class
from gerg_plotting import Animator

# first we need to create a function that will return the figure
def power_spectra_plot(group):
    '''
    Plot the power spectra of vectors u, v, and w
    '''
    data = data_from_df(group)

    # We can calcluate the PSD using the calcluate_PSD method in the Data object
    psd_freq,psd_u,psd_v,psd_w = data.calcluate_PSD(sampling_freq=samp_freq,segment_length=seg_len,theta_rad=theta_rad)

    # Init the subplots
    fig,axes = plt.subplots(nrows=3,figsize=(10,18),layout='constrained')

    # Init the ScatterPlot
    scatter = ScatterPlot(data)
    # Plot the PSD for each vector and set their ylimits
    scatter.power_spectra_density(psd_freq=psd_freq,psd=psd_u,highlight_freqs=highlight_freqs,fig=fig,ax=axes[0])
    scatter.ax.set_title('Vector U')
    scatter.ax.set_ylim(*y_limits)
    scatter.power_spectra_density(psd_freq=psd_freq,psd=psd_v,highlight_freqs=highlight_freqs,fig=fig,ax=axes[1])
    scatter.ax.set_title('Vector V')
    scatter.ax.set_ylim(*y_limits)
    scatter.power_spectra_density(psd_freq=psd_freq,psd=psd_w,highlight_freqs=highlight_freqs,fig=fig,ax=axes[2])
    scatter.ax.set_title('Vector W')
    scatter.ax.set_ylim(*y_limits)
    # Add informative figure title
    scatter.fig.suptitle(f'Auto-spectra at Bin Depth: {group['bin_depth'].min()} m',fontsize=22)
    return scatter.fig

# Extract groups by bin_depth
groups = [group for _,group in df.groupby('bin_depth')]

# Create an animation of the power spectra along depth
Animator().animate(plotting_function=power_spectra_plot,param_dict={'group':groups},gif_filename='example_plots/power_spectra_example.gif',fps=0.75)