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LabelsThis chapter will describe the various options available to change the appearance of the plot. One of the most common things to do is to add labels, using the LAbel command. To put the label ``Time (sec)'' on the x-axis, ``Distance'' on the y-axis, and ``My data'' at the top of the plot, PLT> LA X Time (sec) PLT> LA Y Distance PLT> LA T My data PLT> PYou will notice that only certain PLT commands cause the graphics display to be updated. This allows you to enter several commands quickly without having to wait for the screen to be redrawn after each command. Whenever you want to see what the current graph looks like, you should enter the Plot command or just P. There are also Outer labels (called OX, OY, OT) that can be used. These outer labels provide a simple way to create labels that need to lie on two lines. For example, the commands PLT> LA X Universal PLT> LA OX Time (sec) PLT> Pwould label the x-axis with two lines of text with the word ``Universal'' being written above the words ``Time (sec)''. Now what do you think the following command will do? PLT> LA OT Fun! Fun! Fun! PLT> PIf you try this you will find that only the word ``Fun'' appears. This is because ! is the PLT comment character.
If you wish to enter a PLT command that contains the comment character,
then you must enclose the entire argument in quotation marks:
PLT> LA OT "Fun! Fun! Fun!" PLT> P To remove any label, enter the command with no text; thus, PLT> LA OT PLT> Pwill remove the text ``Fun! Fun! Fun!'' from the graph. The name of the QDP file appears in the File position; thus the command LA F will remove this name. The timestamp that appears at the bottom of the plot can be removed with the Time OFf command and, of course, Time ON will turn it back on. In general, you should leave the file name and timestamp in place, as this information is very useful on a hardcopy. Sometimes, when working with a slow plotting device, you will want to speed things up by not plotting any labels. This can be done the LAbel OFf command. Of course, you should issue the LAbel ON command before making a hardcopy. Text is drawn with PGPLOT; so the standard PGPLOT escape sequences are used. Hence, the commands PLT> LA T \gx\u2 PLT> Pwill label the top of the graph with c2. The default font is the PGPLOT Normal font, which draws rather quickly. For journal quality text, you should override the default font with the FOnt Roman command. This will cause all text, including the numeric labels on the axes, to be written in the nicer looking, but slower plotting, Roman font. Use FOnt ? to get a list of possible fonts. It is also possible to place a numbered label anywhere in the plot. To see this, try PLT> LA 1 Pos 2 4 LIne -45 "Point at (2,4)" PLT> PThe above command plots LAbel 1 at Position (2,4) with a LIne extending out at an angle of -45 degrees to the x-axis and with the text message ``Point at (2,4)''. Each attribute can be set individually. Hence, if you decide you don't like the line extending downwards, you could change the angle with PLT> LA 1 LIne 135 PLT> PThis leaves the pointing position and text unaffected, but resets the angle of the line (and also the justification of the string).
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