pcol: Plot a column of an image

Package: plot

Usage

pcol image col

Parameters

image: Input image containing column to be plotted.

col: The column to be plotted.

wcs = "logical"

The world coordinate system (wcs) to be used for axis labeling when input is f rom images. The following standard world systems are predefined.

logical: Logical coordinates are image pixel coordinates relative to the image currently being displayed.

physical: The physical coordinate system is invariant with respect to linear transformations of the physical image matrix. For example, if the reference image was created by extracting a section of another image, the physical coordinates of an object in the reference image will be the pixel coordinates of the same object in the original image. The physical coordinate system thus provides a consistent coordinate system (a given object always has the same coordinates) for all images, regardless of whether any user world coordinate systems have been defined.

world: The "world" coordinate system is the current default WCS. The default world system is the system named by the environment variable defwcs if defined in the user environment and present in the reference image WCS description, else it is the first user WCS defined for the image (if any), else physical coordinates are returned.

wx1=0., wx2=0., wy1=0., wy2=0.: The range of window (user) coordinates to be included in the plot. If the range of values in x or y = 0, the plot is automatically scaled from the minimum to maximum data values along the degenerate axis.

vx1=0., vx2=0., vy1=0., vy2=0.: NDC coordinates (0-1) of the device plotting viewport. If not set by user, a suitable viewport which allows sufficient room for all labels is used.

pointmode = no: Plot individual points instead of a line?

marker = "box": Marker or line type to be drawn. If pointmode = yes the markers are "point", "box", "cross", "plus", "circle", "hebar", "vebar", "hline", "vline" or "diamond". Any other value defaults to "box". If drawing lines, pointmode = no, the values are "line", "lhist", "bhist". Any other value defaults to "line". "bhist" (box histogram) draws lines to the bottom of the graph while "lhist" does not. In both cases the horizontal histogram lines run between the half way points (reflected at the ends).

szmarker = 0.005: The size of the marker drawn when pointmode = yes.

logx = no, logy = no: Draw the x or y axis in log units, versus linear?

xlabel = "wcslabel", ylabel = "": Label for the X-axis or Y-axis. if xlabel = "wcslabel" the world coordinate system label in the image, if defined, is used.

xformat = "wcsformat": The numerical format for the coordinate labels. The values may be "" (an empty string), %f for decimal format, %h and %H for xx:xx:xx format, and %m and %M for xx:xx.x format. The upper case %H and %M convert degrees to hours. Some images have a recommended x coordinate format defined as a WCS attribute. If the xformat value is "wcsformat" the WCS attribute format will be used. Any other value will override the image attribute.

title = "imtitle": Title for plot. If not changed from the default, the title string from the image header, appended with the columns being plotted, is used.

majrx=5, minrx=5, majry=5, minry=5: The number of major and minor divisions along the x or y axis.

round = no: Round axes up to nice values?

fill = yes: Fill plotting viewport regardless of device aspect ratio?

append = no: Append to an existing plot?

device="stdgraph": Output device.

Description

Plot a specified column of an image. The user can control the plot size and placement, the scaling and labeling of axes. The column can be plotted as a continuous line or individual points with a specified marker.

If append is enabled, previous values for box, fill, round, the plotting viewport (vx1, vx2, vy1, vy2), and the plotting window (wx1, wx2, wy1, wy2) are used.

If the plotting viewport was not set by the user, pcol automatically sets a viewport centered on the device. The default value of fill = yes means the plot spans equal amounts of NDC space in x and y. Setting the value of fill to "no" means the viewport will be adjusted so that the square plot will span equal physical lengths in x and y when plotted. That is, when fill = no, a unity aspect ratio is enforced, and plots appear square regardless of the device aspect ratio. On devices with non square full device viewports (e.g., the vt640), a plot drawn by pcol appears extended in the x direction unless fill = no.

Examples

1. Plot column 128 of image crab.5009 with default parameters:

cl> pcol crab.5009 128

2. Overplot column 128 of crab.red using boxes to mark the added points:

cl> pcol crab.red 128 append+ pointmode+

3. Annotate the axes of a column plot:

cl> pcol crab.5009 64 xlabel="Row Number" ylabel=Intensity

Time requirements

pcol requires about 1.6 cp seconds to plot a column of a 512 square image.