#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
ENGG1811 Lecture Week 4 

Counting heart beats
"""
#%% Import file
import matplotlib.pyplot as plt

#%% Load data and convert to float 
# load the file which contains sampling instants 
# create a list of sampling time (data type: string)
with open('time_data_partial.txt') as f:
    time_str_list = f.read().splitlines() 

# load the file which contains measured voltage 
# create a list of voltage values (data type: string)
with open('voltage_data_partial.txt') as f:
    voltage_str_list = f.read().splitlines() 

# convert the elements in the list to float data type
time_list = [float(t) for t in time_str_list]
voltage_list = [float(v) for v in voltage_str_list]


#%% Count the number tall peaks

# Define a threshold
threshold = 3

# Counting incoporating threshold 
is_peak_list = []

# Enter the code here 
# k is an index for the voltage_list 
for k in range(1,len(voltage_list)-1):  
    voltage_before = voltage_list[k-1]
    voltage_current = voltage_list[k]
    voltage_after = voltage_list[k+1]
    
    if voltage_current > voltage_before and \
       voltage_current > voltage_after: # test if it is a peak or not 
        # if it is a peak 
        if voltage_current > threshold: # is it a tall peak, need threshold
            # tall peak
            is_peak_list.append(1)
        else:
            # Not a peak
            is_peak_list.append(0)

print('The number of tall peaks is:',sum(is_peak_list))              

fig3 = plt.figure()         # create a new figure
plt.plot(time_list,voltage_list)
plt.xlabel('time [s]')    # label for x-axis 
plt.ylabel('voltage [V]')   # label for y-axis
plt.title('Pulse oximeter data') # title of the graph
plt.grid()  # display the grid  
plt.show()  # to display the graph