"""Plot a simple EEG signal trace.
For the EGOW project, week1.

by
    Elliott Forney
    idfah@cs.colostate.edu
    Colorado State University
    2013.04.04
"""

import matplotlib.pyplot as plt
import numpy as np
import json

# load from json
dataHandle = open('s20-gammasys-gifford-unimpaired.json', 'r')
data = json.load(dataHandle)
dataHandle.close()

# pull out first session
data = data[0]

# get sample rate
sampRate = data['sample rate']

# get channel info
chans = data['channels']
nchan = len(chans)

# eeg signals from first trial
eeg = np.array(data['eeg']['trial 1']).T

# get first 5s, ommit trigger channel
ns = 5.0

# seconds down eeg to start plot
shift = 5.0
eeg = eeg[(shift*sampRate):((shift+ns)*sampRate),:nchan]

# demean
eeg -= np.mean(eeg, axis=0)

# set up time and separator to add space between channels
time = np.linspace(0.0,ns,sampRate*ns).repeat(nchan).reshape(eeg.shape)
sep = np.max(np.abs(eeg))*np.arange(nchan-1,-1,-1)

# plot it!
fig = plt.figure(figsize=(12,6))
ax = fig.add_subplot(1,1,1)
ax.plot(time, eeg+sep)
ax.set_yticks(sep)
ax.set_yticklabels(chans)
ax.axis('tight')
plt.show()