# $Id: xw29.py 8233 2008-02-10 15:43:04Z hbabcock $

#  Copyright (C) 2008 Andrew Ross

#  Sample plots using date / time formatting for axes
#
#  This file is part of PLplot.
#
#  PLplot is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Library Public License as published
#  by the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  PLplot is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU Library General Public License for more details.
#
#  You should have received a copy of the GNU Library General Public License
#  along with PLplot; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#
from plplot_py_demos import *

#--------------------------------------------------------------------------
# main
#  
#  Draws several plots which demonstrate the use of date / time formats for
#  the axis labels.
#  Time formatting is done using the system strftime routine. See the 
#  documentation of this for full details of the available formats.
# 
#  1) Plotting temperature over a day (using hours / minutes)
#  2) Plotting 
# 
#  Note: Times are stored as seconds since the epoch (usually 1st Jan 1970). 
#  
#--------------------------------------------------------------------------

def main():
  
  plot1()

  plot2()

  plot3()


# Plot a model diurnal cycle of temperature 
def plot1():

  # Data points every 10 minutes for 1 day 
  npts = 145;

  xmin = 0.0;
  xmax = 60.0*60.0*24.0;    # Number of seconds in a day 
  ymin = 10.0;
  ymax = 20.0;

  x = xmax*arange(npts)/float(npts)
  y = 15.0 - 5.0*cos(2*pi*x/xmax)

  pladv(0)

  plvsta()
  plwind(xmin, xmax, ymin, ymax)

  # Draw a box with ticks spaced every 3 hour in X and 1 degree C in Y. 
  plcol0(1)
  # Set time format to be hours:minutes 
  pltimefmt("%H:%M")
  plbox("bcnstd", 3.0*60*60, 3, "bcnstv", 1, 5)

  plcol0(3)
  pllab("Time (hours:mins)", "Temperature (degC)", "#frPLplot Example 29 - Daily temperature")
  
  plcol0(4)

  plline(x, y)


# Plot the number of hours of daylight as a function of day for a year 
def plot2():

  # Latitude for London 
  lat = 51.5

  npts = 365

  xmin = 0.0
  xmax = npts*60.0*60.0*24.0
  ymin = 0.0
  ymax = 24.0
  
  # Formula for hours of daylight from 
  # "A Model Comparison for Daylength as a Function of Latitude and 
  # Day of the Year", 1995, Ecological Modelling, 80, pp 87-95.
  x = arange(npts)*60.0*60.0*24.0
  p = arcsin(0.39795*cos(0.2163108 + 2*arctan(0.9671396*tan(0.00860*(arange(npts)-186)))))
  d = 24.0 - (24.0/pi)*arccos( (sin(0.8333*pi/180.0) + sin(lat*pi/180.0)*sin(p)) / (cos(lat*pi/180.0)*cos(p)) )
  y = d

  plcol0(1)
  # Set time format to be abbreviated month name followed by day of month 
  pltimefmt("%b %d")
  plenv(xmin, xmax, ymin, ymax, 0, 40)


  plcol0(3)
  pllab("Date", "Hours of daylight", "#frPLplot Example 29 - Hours of daylight at 51.5N")
  
  plcol0(4)

  plline(x, y)
  


def plot3():

  # Warning: mktime is in local time so we need to calculate 
  # offset to get UTC. C time handling is quirky 
  #   t1 = 0
  #   tm = *gmtime(&t1)
  #   t2 = mktime(&tm)
  #   toff = difftime(t1,t2)
  
  #   tm.tm_year = 105 # Years since 1900 
  #   tm.tm_mon = 11   # 0 == January, 11 = December 
  #   tm.tm_mday = 1   # 1 = 1st of month 
  #   tm.tm_hour = 0
  #   tm.tm_min = 0
  #   tm.tm_sec = 0
  
  #   tstart = mktime(&tm)

  tstart = 1133398800
  toff = 0

  npts = 62

  xmin = float(tstart + toff)
  xmax = xmin + npts*60.0*60.0*24.0
  ymin = 0.0
  ymax = 5.0

  i = arange(npts)
  imin = float(npts)/2.0-abs(i - float(npts)/2.0)
  x = xmin + i*60.0*60.0*24.0
  y = 1.0 + sin(2*pi*i/7.0) + exp( imin / 31.0)
  pladv(0)

  plvsta()
  plwind(xmin, xmax, ymin, ymax)

  plcol0(1)
  # Set time format to be ISO 8601 standard YYYY-MM-DD. Note that this is
  # equivalent to %f for C99 compliant implementations of strftime. 
  pltimefmt("%Y-%m-%d")
  # Draw a box with ticks spaced every 14 days in X and 1 hour in Y. 
  plbox("bcnstd", 14*24.0*60.0*60.0,14, "bcnstv", 1, 4)

  plcol0(3)
  pllab("Date", "Hours of television watched", "#frPLplot Example 29 - Hours of television watched in Dec 2005 / Jan 2006")
  
  plcol0(4)

  plpoin(x, y, 2)
  plline(x, y)
	    
main()