plot

#!/usr/bin/python

from __future__ import division
from numpy import *
import matplotlib.pyplot as plt
import sys
import getopt

usage = '''plot [option] 'functions' minx maxx [miny maxy]

Options:
  -h, --help    print this message
  -p, --pdf     generate PDF plot

Generate a PNG (default) or PDF plot of the given function(s). The
independent variable in the function(s) is x. Multiple functions are
separated by a semicolon. The min and max values can be given as
expressions. The output is typically redirected to a file.

Example:
  plot 'tan(x); x' pi 3*pi/2-.01 0 5 > plot.png

'''

# Handle the options.
try:
  opts, args = getopt.getopt(sys.argv[1:], 'hp', ['help', 'pdf'])
except getopt.GetoptError as err:
  sys.stderr.write(str(err) + '\n\n')
  sys.stderr.write(usage)
  sys.exit()

fmt = 'png'
for o, a in opts:
  if o == '-p' or o == '--pdf':
    fmt = 'pdf'
  else:
    sys.stderr.write(usage)
    sys.exit()

# Handle the arguments.
try:
  fcns = [x.strip() for x in args[0].split(';')]
  minx = eval(args[1])
  maxx = eval(args[2])
except IndexError:
  sys.stderr.write(usage)
  sys.exit()

plt.xlim(minx, maxx)
try:
  miny = float(args[3])
  maxy = float(args[4])
  plt.ylim(miny, maxy)
except IndexError:
  pass

# Make the plot.
x = linspace(minx, maxx, 100)
for i, f in enumerate(fcns):
  y = eval(f)
  plt.plot(x, y, "-", linewidth=2)
plt.legend(fcns, frameon=False);
plt.minorticks_on()
plt.grid(which='both', color='#aaaaaa')

# Output the plot.
if fmt == 'pdf':
  plt.savefig(sys.stdout, format='pdf')
else:
  plt.savefig(sys.stdout, format='png')