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# Copyright (C) 2008 Andrew Ross
# Copyright (C) 2008-2016 Alan W. Irwin
# 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 Library General 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 numpy import *
import calendar
#--------------------------------------------------------------------------
# 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(w):
w.plsesc('@')
plot1(w)
plot2(w)
plot3(w)
plot4(w)
# Restore defaults
w.plsesc('#')
# Must be done independently because otherwise this changes output files
# and destroys agreement with C examples.
#w.plcol0(1)
# Plot a model diurnal cycle of temperature
def plot1(w):
# Data points every 10 minutes for 1 day
npts = 73;
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)
xerr1 = x-60.0*5.0
xerr2 = x+60.0*5.0
yerr1 = y-0.1
yerr2 = y+0.1
w.pladv(0)
w.plsmaj(0.0,0.5)
w.plsmin(0.0,0.5)
w.plvsta()
w.plwind(xmin, xmax, ymin, ymax)
# Draw a box with ticks spaced every 3 hour in X and 1 degree C in Y.
w.plcol0(1)
# Set time format to be hours:minutes
w.pltimefmt("%H:%M")
w.plbox("bcnstd", 3.0*60*60, 3, "bcnstv", 1, 5)
w.plcol0(3)
w.pllab("Time (hours:mins)", "Temperature (degC)", "@frPLplot Example 29 - Daily temperature")
w.plcol0(4)
w.plline(x, y)
w.plcol0(2)
w.plerrx(xerr1,xerr2,y)
w.plcol0(3)
w.plerry(x,yerr1,yerr2)
w.plsmin(0.0,1.0)
w.plsmaj(0.0,1.0)
# Plot the number of hours of daylight as a function of day for a year
def plot2(w):
# 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
w.plcol0(1)
# Set time format to be abbreviated month name followed by day of month
w.pltimefmt("%b %d")
w.plprec(1,1)
w.plenv(xmin, xmax, ymin, ymax, 0, 40)
w.plcol0(3)
w.pllab("Date", "Hours of daylight", "@frPLplot Example 29 - Hours of daylight at 51.5N")
w.plcol0(4)
w.plline(x, y)
w.plprec(0,0)
def plot3(w):
# number of seconds elapsed since the Unix epoch (1970-01-01, UTC) for
# 2005-12-01, UTC.
xmin = w.plctime(2005,11,1,0,0,0.)
npts = 62
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)
w.pladv(0)
w.plvsta()
w.plwind(xmin, xmax, ymin, ymax)
w.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.
w.pltimefmt("%Y-%m-%d")
# Draw a box with ticks spaced every 14 days in X and 1 hour in Y.
w.plbox("bcnstd", 14*24.0*60.0*60.0,14, "bcnstv", 1, 4)
w.plcol0(3)
w.pllab("Date", "Hours of television watched", "@frPLplot Example 29 - Hours of television watched in Dec 2005 / Jan 2006")
w.plcol0(4)
w.plssym(0.0,0.5)
w.plpoin(x, y, 2)
w.plline(x, y)
def plot4(w):
# TAI-UTC (seconds) as a function of time.
# Continuous time unit is Besselian years from whatever epoch is
# chosen below. Could change to seconds (or days) from the
# epoch, but then would have to adjust xlabel_step below.
scale = 365.242198781
# MJD epoch (see <https://en.wikipedia.org/wiki/Julian_day>).
# This is only set for illustrative purposes, and is overwritten
# below for the time-representation reasons given in the
# discussion below.
epoch_year = 1858
epoch_month = 11
epoch_day = 17
epoch_hour = 0
epoch_min = 0
epoch_sec = 0.
# To illustrate the time-representation issues of using the MJD
# epoch, in 1985, MJD was roughly 46000 days which corresponds to
# 4e9 seconds. Thus, for the -DPL_DOUBLE=ON case where PLFLT is
# a double which can represent continuous time to roughly 16
# decimal digits of precision the time-representation error is
# roughly ~400 nanoseconds. Therefore the MJD epoch would be
# acceptable for the plots below in the -DPL_DOUBLE=ON case.
# However, that epoch is obviously not acceptable for the
# -DPL_DOUBLE=OFF case where PLFLT is a float which can represent
# continuous time to only ~7 decimal digits of precision
# corresponding to a time representation error of 400 seconds (!)
# in 1985. For this reason, we do not use the MJD epoch below
# and instead choose the best epoch for each case to minimize
# time-representation issues.
for kind in range(7):
if kind == 0:
# Choose midpoint to maximize time-representation precision.
epoch_year = 1985
epoch_month = 0
epoch_day = 2
epoch_hour = 0
epoch_min = 0
epoch_sec = 0.
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
xmin = w.plctime(1950,0,2,0,0,0.)
xmax = w.plctime(2020,0,2,0,0,0.)
npts = 70*12 + 1
ymin = 0.0
ymax = 36.0
time_format = "%Y%"
if_TAI_time_format = True
title_suffix = "from 1950 to 2020"
xtitle = "Year"
xlabel_step = 10.
elif kind == 1 or kind ==2:
# Choose midpoint to maximize time-representation precision.
epoch_year = 1961
epoch_month = 7
epoch_day = 1
epoch_hour = 0
epoch_min = 0
epoch_sec = 1.64757
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
xmin = w.plctime(1961,7,1,0,0,1.64757-.20)
xmax = w.plctime(1961,7,1,0,0,1.64757+.20)
npts = 1001
ymin = 1.625
ymax = 1.725
time_format = "%S%2%"
title_suffix = "near 1961-08-01 (TAI)"
xlabel_step = 0.05/(scale*86400.)
if kind == 1:
if_TAI_time_format = True
xtitle = "Seconds (TAI)"
else:
if_TAI_time_format = False
xtitle = "Seconds (TAI) labelled with corresponding UTC"
elif kind == 3 or kind ==4:
# Choose midpoint to maximize time-representation precision.
epoch_year = 1963
epoch_month = 10
epoch_day = 1
epoch_hour = 0
epoch_min = 0
epoch_sec = 2.6972788
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
xmin = w.plctime(1963,10,1,0,0,2.6972788-.20)
xmax = w.plctime(1963,10,1,0,0,2.6972788+.20)
npts = 1001
ymin = 2.55
ymax = 2.75
time_format = "%S%2%"
title_suffix = "near 1963-11-01 (TAI)"
xlabel_step = 0.05/(scale*86400.)
if kind == 3:
if_TAI_time_format = True
xtitle = "Seconds (TAI)"
else:
if_TAI_time_format = False
xtitle = "Seconds (TAI) labelled with corresponding UTC"
elif kind == 5 or kind == 6:
# Choose midpoint to maximize time-representation precision.
epoch_year = 2009
epoch_month = 0
epoch_day = 1
epoch_hour = 0
epoch_min = 0
epoch_sec = 34.
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
xmin = w.plctime(2009,0,1,0,0,34.-5.)
xmax = w.plctime(2009,0,1,0,0,34.+5.)
npts = 1001
ymin = 32.5
ymax = 34.5
time_format = "%S%2%"
title_suffix = "near 2009-01-01 (TAI)"
xlabel_step = 1./(scale*86400.)
if kind == 5:
if_TAI_time_format = True
xtitle = "Seconds (TAI)"
else:
if_TAI_time_format = False
xtitle = "Seconds (TAI) labelled with corresponding UTC"
i = arange(npts)
x = xmin + i*(xmax-xmin)/float(npts-1)
y = zeros(npts)
for j in range(npts):
tai = x[j]
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
(tai_year, tai_month, tai_day, tai_hour, tai_min, tai_sec) = w.plbtime(tai)
# Calculate residual using tai as the epoch to nearly maximize time-representation precision.
w.plconfigtime(scale, 0., 0., 0x0, True, tai_year, tai_month, tai_day, tai_hour, tai_min, tai_sec)
# Calculate continuous tai with new epoch.
tai = w.plctime(tai_year, tai_month, tai_day, tai_hour, tai_min, tai_sec)
# Calculate broken-down utc (with leap seconds inserted) from continuous tai with new epoch.
w.plconfigtime(scale, 0., 0., 0x2, True, tai_year, tai_month, tai_day, tai_hour, tai_min, tai_sec)
(utc_year, utc_month, utc_day, utc_hour, utc_min, utc_sec) = w.plbtime(tai)
# Calculate continuous utc from broken-down utc using same epoch as for the continuous tai.
w.plconfigtime(scale, 0., 0., 0x0, True, tai_year, tai_month, tai_day, tai_hour, tai_min, tai_sec)
utc = w.plctime(utc_year, utc_month, utc_day, utc_hour, utc_min, utc_sec)
# Convert residuals to seconds.
y[j]=(tai-utc)*scale*86400.
w.pladv(0)
w.plvsta()
w.plwind(xmin, xmax, ymin, ymax)
w.plcol0(1)
if if_TAI_time_format:
w.plconfigtime(scale, 0., 0., 0x0, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
else:
w.plconfigtime(scale, 0., 0., 0x2, True, epoch_year, epoch_month, epoch_day, epoch_hour, epoch_min, epoch_sec)
w.pltimefmt(time_format)
w.plbox("bcnstd", xlabel_step, 0, "bcnstv", 0., 0)
w.plcol0(3)
w.pllab(xtitle, "TAI-UTC (sec)", "@frPLplot Example 29 - TAI-UTC " + title_suffix)
w.plcol0(4)
w.plline(x, y)
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