<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 2002-2-1 (1.71) original version by: Nikos Drakos, CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>5.1.1.3 Calendar time coordinates</TITLE> <META NAME="description" CONTENT="5.1.1.3 Calendar time coordinates"> <META NAME="keywords" CONTENT="GMT_Docs"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1"> <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> <LINK REL="STYLESHEET" HREF="GMT_Docs.css"> <LINK REL="previous" HREF="node82.html"> <LINK REL="up" HREF="node80.html"> <LINK REL="next" HREF="node84.html"> </HEAD> <BODY bgcolor="#ffffff"> <!--Navigation Panel--> <A NAME="tex2html3809" HREF="node84.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html3803" HREF="node80.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html3799" HREF="node82.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html3805" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html3807" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html3810" HREF="node84.html">5.1.2 Cartesian logarithmic projection</A> <B> Up:</B> <A NAME="tex2html3804" HREF="node80.html">5.1.1 Cartesian linear transformation</A> <B> Previous:</B> <A NAME="tex2html3800" HREF="node82.html">5.1.1.2 Geographic coordinates</A> <B> <A NAME="tex2html3806" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html3808" HREF="node258.html">Index</A></B> <BR> <BR> <!--End of Navigation Panel--> <H3><A NAME="SECTION001311300000000000000"></A> <A NAME="sec:time"></A><A NAME="21485"></A> <A NAME="21486"></A> <A NAME="21487"></A> <BR> 5.1.1.3 Calendar time coordinates </H3> <P> <DIV ALIGN="CENTER"><A NAME="fig:GMT_linear_cal"></A><A NAME="21681"></A> <TABLE> <CAPTION ALIGN="BOTTOM"><STRONG>Figure 5.3:</STRONG> Linear transformation of calendar coordinates.</CAPTION> <TR><TD> <DIV ALIGN="CENTER"><IMG WIDTH="524" HEIGHT="269" ALIGN="BOTTOM" BORDER="0" SRC="img98.png" ALT="\includegraphics{scripts/GMT_linear_cal}"></DIV></TD></TR> </TABLE> </DIV> <P> Several particular issues arise when we seek to make linear plots using calendar date/time as the input coordinates. As far as setting up the coordinate transformation we must indicate whether our input data have absolute time coordinates or relative time coordinates. For the former we append <B>T</B> after the axis scale (or width), while for the latter we append <B>t</B> at the end of the <B>-Jx</B> (or <B>-JX</B>) option. However, other command line arguments (like the <B>-R</B> option) may already specify whether the time coordinate is absolute or relative. An absolute time entry must be given as [<I>date</I>]<B>T</B>[<I>clock</I>] (with <I>date</I> given as <I>yyyy</I>[-<I>mm</I>[-<I>dd</I>]], <I>yyyy</I>[-<I>jjj</I>], or <I>yyyy</I>[-<B>W</B><I>ww</I>[-<I>d</I>]], and <I>clock</I> using the <I>hh</I>[:<I>mm</I>[:<I>ss</I>[<I>.xxx</I>]]] 24-hour clock format) whereas the relative time is simply given as the units of time since the epoch followed by <B>t</B> (see <B>TIME_UNIT</B> and <B>TIME_EPOCH</B> for information on specifying the time unit and the epoch). As a simple example, we will make a plot of a school week calendar (Figure <A HREF="#fig:GMT_linear_cal">5.3</A>). <P> <BR CLEAR="ALL"> <HR> <BR> <PRE>gmtset PLOT_DATE_FORMAT o TIME_WEEK_START Sunday PLOT_CLOCK_FORMAT -hham TIME_FORMAT_PRIMARY full psbasemap -R2001-9-24T/2001-9-29T/T07:0/T15:0 -JX4i/-2i -Ba1Kf1kg1d/a1Hg1hWsNe -P > GMT_linear_cal.ps </PRE> <BR CLEAR="ALL"> <HR> <P> When the coordinate ranges provided by the <B>-R</B> option and the projection type given by <B>-JX</B> (including the optional <B>d</B>, <B>g</B>, <B>t</B> or <B>T</B>) conflict, <A NAME="tex2html1324" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A> will warn the users about it. In general, the options provided with <B>-JX</B> will prevail. <P> <A NAME="21525"></A> <A NAME="21526"></A> <A NAME="21527"></A> <P> <A NAME="21528"></A> <A NAME="21529"></A> <A NAME="21530"></A> <A NAME="21531"></A> <A NAME="21532"></A> <P> <HR> <!--Navigation Panel--> <A NAME="tex2html3809" HREF="node84.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html3803" HREF="node80.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html3799" HREF="node82.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html3805" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html3807" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html3810" HREF="node84.html">5.1.2 Cartesian logarithmic projection</A> <B> Up:</B> <A NAME="tex2html3804" HREF="node80.html">5.1.1 Cartesian linear transformation</A> <B> Previous:</B> <A NAME="tex2html3800" HREF="node82.html">5.1.1.2 Geographic coordinates</A> <B> <A NAME="tex2html3806" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html3808" HREF="node258.html">Index</A></B> <!--End of Navigation Panel--> <ADDRESS> Paul Wessel 2011-02-27 </ADDRESS> </BODY> </HTML>