I have a pressure transducer signal along with the crank angle from an internal combustion engine. A sample data is available here.
Now, I am trying to plot the spectrogram of this pressure signal using the code below:
import matplotlib.pyplot as plt
import numpy as np
data = np.genfromtxt('data.dat', skiprows = 1, delimiter='\t')
angle = data[:, 0]
pressure = data[:, 1]
fig = plt.figure(figsize=(5.15, 5.15))
fig.clf()
plot = plt.subplot(111)
cax = plt.specgram(pressure * 100000, NFFT = 512, Fs = 10000)
plot.grid(False, which="major")
plot.set_xlim(right = max(cax[2]))
plot.set_xlabel('Time (s)', labelpad=6)
plot.set_ylabel('Frequency (Hz)', labelpad=6)
y_min, y_max = plot.get_ylim()
plt.gca
cbar = plt.colorbar(orientation='vertical', ax = plot, fraction = 0.046, pad = 0.04) #fraction=0.0458, pad=0.04)
cbar.set_label('Power spectral density (dB)', rotation=-90)
plt.show()
Now I want the spectrogram to be plotted with angle on the x-axis. How can I convert the x-axis to angles as available in the data file?
Regards,
nxkr