"""
  COMP 364 Lecture 15: Simple plots
  Author: Mathieu Perreault
"""

import matplotlib.pyplot as plt
import sys, math

# Generate some data points and put them in a file. Optional, could directly generate to lists.
of = open('data.txt', 'w')
for i in [x*0.1 for x in range(0,100)]:
  of.write("%s\t%s\n" %(i, math.sin(i)))
of.close()

# Simple chart
x = []
y = []
for line in open('data.txt'):
  values = line.strip('\n').split()
  x.append(float(values[0]))
  y.append(float(values[1]))
  
plt.figure()
plt.plot(x,y, 'g.')
plt.show() # Press the X button on this first chart to plot the second one.


# Not so simple chart, filtering on the threshold (second argument)
x = []
y = []
xb = []
yb = []
for line in open('data.txt'):
  values = line.strip('\n').split()
  yvalue = float(values[1])
  if math.fabs(yvalue) < float(sys.argv[1]):
    x.append(float(values[0]))
    y.append(yvalue)
  else:
    xb.append(float(values[0]))
    yb.append(yvalue)
  
plt.figure()
plt.plot(x,y,'b.')
plt.hold(True)
plt.plot(xb,yb,'g.')
# Further enhancements
plt.title('Sin(x) function')
plt.xlabel('x values')
plt.ylabel('y values')
plt.legend(['|sin(x)| < ' + sys.argv[1], '|sin(x)| >= ' + sys.argv[1]])
plt.show()