helplog.22: graphics, windowing, zooming, gtools, identify

Frank Valdes wrote on Feb 07, 2005

NUMBER:	22
KEYWORDS:	graphics, windowing, zooming, gtools, identify
DATE:	Mon Feb  7 09:01:45 MST 2005
FROM:	valdes

Q:	I've been able to get to the wavelength calibration part of
	my spectral reduction, and am currently assigning wavelengths to my
	arc..however there was a bad column in the chip, and thus there is
	one segment of my plot that has a horrendous spike...now I have
	tried to find a way to remove that spike and re-plot my arc
	spectrum (after extraction, naturally), but haven't found a way...I
	also tried to find a way to change the y-axis (i.e. :y 300 500) but
	that doesn't seem to work when I am executing the task IDENTIFY.

A:	There are two questions here.  One is editing the data in an
	applicatation graph, what you called "remove that spike".  There is
	no generic way to edit data in a graph though some applications
	such as SPLOT and SPECPLOT let you do that.

	The second question about replotting the data is very common.  This
	is how one "expands" the plot to see finer detail.  In many of the
	science applications, though not all and not in the core PLOT or
	IMAGES package, there is an interface called GTOOLS.  If you type
	"help gtools" you can read about it.  These are commands to tell
	the application how to redraw the graph.  So in IDENTIFY you would
	do something like 'w' 'e' 'e' to expand the graph.  Also 'w' 't' to
	put an upper limit in order to chop off the spike.  It is important
	to know that 'w' 'a' will return you to autoscale which is what the
	applications usually do by default.  So there are lots of
	keystrokes available.  Note also that the 'z' and 'p' keystrokes in
	IDENTIFY let you zoom around the marked features and then cancel
	the zoom.  But what I most often use with IDENTIFY are the e and a
	window commands.

---

Last post on Feb 07, 2005