graph: Graph one or more image sections or lists

Package: plot

Usage

graph input

Parameters

input: List of operands to be graphed. May be STDIN, or one or more image sections or lists.

wx1=0., wx2=0., wy1=0., wy2=0.: The range of user coordinates spanned by the plot. If the range of values in x or y = 0, the plot is automatically scaled from the minimum to maximum data value along the degenerate dimension.

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.

In addition to these three reserved WCS names, the name of any user WCS defined for the reference image may be given. A user world coordinate system may be any linear or nonlinear world system.

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

pointmode = no: If pointmode = yes, plot points or markers at data values, rather than connected lines.

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 a marker in NDC coordinates (0 to 1 spans the screen). If zero and the input operand is a list, marker sizes are taken individually from the third column of each list element. If positive, all markers are of size szmarker. If negative and the input operand is a list, the size of a marker is the third column of each list element times the absolute value of szmarker.

ltypes = "", colors = ""

List of line types and colors to use when graphing multiple data sets. The lists are comma or space separate integer numbers. If no list is given the line types and colors will cycle through the range of values. If a list is given then the values are used in order and if the list is exhausted before the data the last value is used for all remaining data sets. The line types have values between 1 and 4:

1 - solid line
2 - dashed line
3 - dotted line
4 - dot-dash line

The colors have values between 1 and 9. The colors associated with each number depend on the graphics device. For example "xgterm" colors are assigned by X resources.

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

title = "imtitle": Plot title. If title = "imtitle" and the first operand in input is an image, the image title is used as the plot title.

xformat = "wcsformat", yformat = "": 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. For images a recommended x coordinate format may be 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.

box = yes: Draw axes at the perimeter of the plotting window.

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

axis = 1: Axis along which the projection is to be computed, if an input operand is an image section of dimension 2 or higher. Axis 1 is X (line average), 2 is Y (column average), and so on.

transpose = no: Swap the X and Y axes of the plot. If enabled, the axes are transposed after the optional linear transformation of the X-axis.

logx = no, logy = no: Log scale the X or Y axis. Zero or negative values are indefinite and will not be plotted, but are tolerated.

ticklabels = yes: Label the tick marks.

majrx=5, minrx=5, majry=5, minry=5: Number of major tick marks on each axis; number of minor tick marks between major tick marks. Ignored if log scaling is in effect for an axis.

lintran = no: Perform a linear transformation of the X-axis upon input. Used to assign logical coordinates to the indices of pixel data arrays (image sections).

p1=0, p2=0, q1=0, q2=1: If lintran is enabled, pixel index P1 is mapped to Q1, and P2 to Q2. If P1 and P2 are zero, P1 is set to 1 and P2 to the number of pixels in the input array.

round = no: Extend the axes up to "nice" values.

overplot = no: Overplot on an existing plot. All axis scaling and labeling parameters apply.

append = no: Append to an existing plot. The previous axis is used and the axis scaling and labeling parameters are ignored.

device = "stdgraph": The output device.

Description

Graph graphs one or more lists or image sections; lists and image sections may be mixed in the input list at will. If the curves are not all the same length the plot will be scaled to the longest curve and all curves will be plotted left justified. If an image section operand has more than one dimension the projection (average) along a designated axis will be computed and plotted. By default, a unique dash pattern is used for each curve, up to a maximum of 4.

List input may be taken from the standard input or from a file, and consists of a sequence of Y values, X and Y values, or X, Y, and marker size values, one pair of coordinates per line in the list. If the third column of a list contains positive numbers, they are interpreted as NDC marker sizes, optionally scaled by the absolute value of szmarker. If you want the third column of a list to be interpreted as WCS coordinates, indicating errors for example, the marker sizes should be entered as negative numbers. Blank lines, comment lines, and extra columns are ignored. The first element in the list determines whether the list is a Y list or and X,Y list; it is an error if an X,Y list has fewer than two coordinates in any element. INDEF valued elements appear as gaps in the plot.

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. The overplot parameter overplots a new plot including any new axis scaling and labeling.

By default, the plot drawn will fill the device viewport, if the viewport was either specified by the user or automatically calculated by graph. Setting the value of fill to "no" means the viewport will be adjusted so that equal numbers of data values in x and y will occupy equal lengths 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 graph appears extended in the x direction unless fill = no.

Examples

1. Plot the output of a list processing filter:

cl> ... list_filter | graph

2. Plot a graph entered interactively from the terminal:

cl> graph STDIN

3. Overplot two lists:

cl> graph list1,list2

4. Graph line 128 of image "pix":

cl> graph pix[*,128]

5. Graph the average of columns 50 through 100:

cl> graph pix[50:100,*] axis=2

6. Graph a list in point plot mode:

cl> graph list po+

7. Annotate a graph:

cl> graph pix[*,10],pix[*,20] xlabel=column\
>>> ylabel=intensity title="lines 10 and 20 of pix"

8. Direct the graph to the standard plotter device:

cl> graph list device=stdplot

Bugs

Indefinites are not recognized when computing image projections.