add_hline

Context: lines

Synopsis

Creates a horizontal line.

Syntax

add_hline([id,] y [,attributes])

Horizontal lines can also be created directly from the GUI using the
"Annotate" menu item.

Description

The function arguments.

Argument	Description
id	A ChipsId structure identifying the item.
y	The location along the vertical axis through which the horizontal line should pass; the current coordinate system is used if the "coordsys" attribute is not set.
attributes	Configure object properties by giving an attribute string (a space-separated list of key=value pairs), list, dictionary, or a ChIPS object.

The add_hline command creates a horizontal line at the specified y location. The location of the line can be specified in data, pixel, frame, or plot normalized coordinates by using the 'coordsys' attribute. The line extends infinitely along the horizontal. It is clipped appropriately by its coordinate system (e.g. lines in data coordinates or plot normalized will be clipped at plot boundaries).

This command is the same as creating a horizontal line segment with add_line ("ahelp add_line") and setting the "extend" property so that it extends both ends of the line; see the Line Extend section of "ahelp chipsopt".

Customizing the Line

There are several attributes that control the line characteristics. The attributes can be set to the ChIPS defaults, values provided in the add_hline command, or values from the user's preference file.

The attributes may also be modified with the set_line command at any time; see "ahelp set_line" and "ahelp setget" for more information.

Please see the section "Line Preferences and Attributes" below the examples for a list of the line attributes.

Examples

Example 1

chips> add_hline(0.1)

Add a horizontal line at y=0.1 in the current coordinate system.

Example 2

chips> add_hline(0.1, ['coordsys', PLOT_NORM])

Add the line at one-tenth of the height of the plot.

Example 3

chips> hl = ChipsLine()
chips> hl.color = 'blue'
chips> hl.thickness = 8.0
chips> hl.stem = 'MyLine'
chips> add_axis(XY_AXIS, 0, 0, 200)
chips> add_hline(100, hl)

Populate the "hl" structure with the attribute values, then add a horizontal line that passes through the point 100 on the y-axis.

Line Preferences and Attributes

The attributes associated with lines are given in the following table, where the "Set?" column refers to whether the attribute can be change using the set_line() command. To change the line preference settings prepend "line." to the attribute name.

Attribute	Description	Options	Default	Set?
color	line color	name or hex; see the Color section of "ahelp chipsopt"	default	Yes
coordsys	coordinate system for the line	PIXEL, WINDOW_NORM, FRAME_NORM, PLOT_NORM, DATA	see "ahelp coordsys"	No
depth	Integer value indicating line depth	see the Depth section of "ahelp chipsopt"	default	Yes
extend	Should the line extend to infinity (segment vs ray)	One of "none", "both", "start", "end", chips_extend_none, chips_extend_both, chips_extend_start, or chips_extend_end.	chips_extend_none	Yes
stem	stem used for line id	An alpha-numeric character sequence that does not contain a space	line	No
style	stipple pattern used to draw the line segment	see the Line Style section of "ahelp chipsopt"	chips_solid	Yes
thickness	line thickness	0.5 to 10.0; see the Thickness section of "ahelp chipsopt"	1	Yes

Bugs

See the bugs pages on the ChIPS website for an up-to-date listing of known bugs.