Concepts: Values

This document describes how attribute values - such as the line style, symbol color, and ticklabel formats - are specified. The Attributes concept documentation describes how you change the attributes of an object.

• Booleans
• Color
• Contour Mode
• Depth
• Export
• Fill Patterns
• Font
• Font Style
• Line Style
• Object Type
• Symbol Style
• Text Alignment
• Text Formatting
• Thickness
• Tick Format
• Tick Mode
• Tick Style

Booleans

Numerous object attributes are represented as boolean states, such as object visibility and fill properties. Behaviors like auto limit calculations are also boolean.

Depending on the context, a boolean value may be specifed as an integer or a string value. For example, when using an attribute string, the string values are used ("fill=true"), but when using an attribute list to set values either a numeric or a string may be used ({"fill",1} or {"fill","true"}). For integer representations, a 0 equates to false while a 1 equates to true. For string representations, a wide range of values may be used to specify the boolean settings.

The predefined Python True and False boolean values are also supported.

Color

Color is an attribute of nearly all objects in ChIPS, and there is a vast palette available. The colors documentation describes how to specify color values and how to set the color attributes of objects.

Since the colors used for video displays are often not optimal for hardcopies, ChIPS provides a special color identifier "default". Any item set to "default" will use user-configurable default colors for foreground and background colors in terminals as well as hardcopies.

Colors may be specified by name ( "lime", "gray", "black") or as hex values (RRGGBB where 0xff0000 = Red, 0x00ff00 = Green, 0x0000ff = Blue).

Contour Mode

The contour mode sets how levels are determined in contours.

The following contour modes are supported:

Depth

Depth control allows the user to specify the depth at which each object is placed within a frame.

When objects are created, they are assigned a depth value. The depth to which an object is assigned, along with the order that the objects were added to the depth, determines the rendering order of the frame. Depths are rendered from the lowest depth value greater than 0 to the highest depth value in use. Objects at higher depths may overlap lower objects.

Depths are specified as positive integers where the value 1 represents the lowest items ("farther" from the top).

The depth value 0 ("default", V_USE_DEFAULT_DEPTH) represents a special case. If the value is default, then default frame depth is used. The value of the frame default is initialized to the value of the preference "default.depth", but may be modified by using the set_default_depth command. The new setting does not affect the depth of existing objects, only new ones created after the call to set_default_depth.

Fill Patterns

This is new to CIAO 4.1; in CIAO 4.0 regions and histograms could only be filled with a solid pattern.

Fill patterns apply to the histogram and regions objects. If they are filled, a fill color may also be specified. The supported fill patterns are:

Export

Export attributes are used to control the output files generated by ChIPS. Users may specify various file formats. In addition, color format, scaling, margins, and other attributes of the output may be specified.

Attributes that are specific to page layouts (margins, page size, orientation, etc.) only apply to pdf and ps formats.

Font

ChIPS provides four installed fonts: times, helvetica, courier, and greek.

In addition to the standard fonts, ChIPS provides limited support for users to load their own fonts. The user-loaded fonts work on the screen displays and output png and jpg formats, but do not work in ps, eps, or pdf output formats. Furthermore, the user-loaded fonts do not get saved in state files.

# Python
   load_font("bookman","/my_fonts/bookman.pfb", chips_normal)
   load_font("bookman","/my_fonts/bookman_b.pfb", chips_bold)
   load_font("bookman","/my_fonts/bookman_i.pfb", chips_italic)
   load_font("bookman","/my_fonts/bookman_bi.pfb", chips_bolditalic)
   add_label(.1,.5,"AbCdEfGhIjKlM","font=bookman fontstyle=bold")

% S-Lang
   load_font("bookman","/my_fonts/bookman.pfb", chips_normal);
   load_font("bookman","/my_fonts/bookman_b.pfb", chips_bold);
   load_font("bookman","/my_fonts/bookman_i.pfb", chips_italic);
   load_font("bookman","/my_fonts/bookman_bi.pfb", chips_bolditalic);
   add_label(.1,.5,"AbCdEfGhIjKlM","font=bookman fontstyle=bold");

Font Style

Font styles allow the user to add emphasis to labels by changing their appearance. Font styles for user-loaded fonts are dependent on whether the appropriate files have been provided.

The pre-installed Greek font only supports normal font style.

Line Style

Line styles refer to the stipple pattern used to draw lines and edges for objects such as lines, curves, regions, and grids.

The following line styles are supported:

Object Type

ChIPS utilizes various objects to create figures. Ii is necessary to specify the object to which an action should be applied when using any of the non-object-specific commands, e.g. move, shuffle, set_attribute.

Object type are represented as an enumeration in ChIPS. It is possible to specify an object type using either the enumeration (chips_line) or its numeric value (11 for chips_line).

Symbol Style

Symbol styles refer to the glyphs used to represent points, curve data points, and histogram data points.

The following symbol styles are supported:

Text Alignment

Text alignment determines how a label is displayed in relation to the associated location. It is sometimes referred to as text justification. For instance, text that is left-justified has its leftmost edge placed at the specified location or reference point. Right-justified means the text is placed so that the rightmost portion of the label ends at the specified location.

For vertical alignment the baseline of the text (neglecting descenders such as "p", "g", or "q") is the 0 or base. The top is determined by the height of standard glyphs in the label.

Text Alignments may be specified as numeric values or as the predefined values specified in the table below. Numeric values greater than 1 or less than 0 result in the labels shifting over by a ratio based on the height or width of the text. For instance, a horizontal alignment of -1 will place the label to the right of anchor position, by the length of the label.

Text Formatting

ChIPS labels support a number of simple latex formatting sequences including subscripts, superscripts, fonts, font styles, colors, and special symbols.

A number of symbols have been added to CIAO 4.1, such as \sun (also known as \odot), \circ, and the planets (e.g. \mercury), and other symbols. They are marked with a new label in the "Supported LaTeX Symbols" table below.

Since both Python and S-Lang interpret \ as a control character, it should either be preceeded by another backslash, as in the examples below, or the text can be labelled as containing \ symbols by saying:

# Python
  r"y = \alpha^2_i"

% S-Lang
  "y = \alpha^2_i"R

Some examples of the LaTeX support in ChIPS:

The following formatting sequences are supported:

Supported Latex Symbols
Symbol	Description
\AA	Angstrom symbol
\alpha	lowercase greek alpha character
\Alpha	uppercase greek alpha character
\beta	lowercase greek beta character
\Beta	uppercase greek beta character
\gamma	lowercase greek gamma character
\Gamma	uppercase greek gamma character
\delta	lowercase greek delta character
\Delta	uppercase greek delta character
\epsilon	lowercase greek epsilon character
\Epsilon	uppercase greek epsilon character
\zeta	lowercase greek zeta character
\Zeta	uppercase greek zeta character
\eta	lowercase greek eta character
\Eta	uppercase greek eta character
\theta	lowercase greek theta character
\Theta	uppercase greek theta character
\iota	lowercase greek iota character
\Iota	uppercase greek iota character
\kappa	lowercase greek kappa character
\Kappa	uppercase greek kappa character
\lambda	lowercase greek lambda character
\Lambda	uppercase greek lambda character
\mu	lowercase greek mu character
\Mu	uppercase greek mu character
\nu	lowercase greek nu character
\Nu	uppercase greek nu character
\xi	lowercase greek xi character
\Xi	uppercase greek xi character
\omicron	lowercase greek omicron character
\Omicron	uppercase greek omicron character
\pi	lowercase greek pi character
\Pi	uppercase greek pi character
\rho	lowercase greek rho character
\Rho	uppercase greek rho character
\sigma	lowercase greek sigma character
\Sigma	uppercase greek sigma character
\tau	lowercase greek tau character
\Tau	uppercase greek tau character
\upsilon	lowercase greek upsilon character
\Upsilon	uppercase greek upsilon character
\phi	lowercase greek phi character
\Phi	uppercase greek phi character
\chi	lowercase greek chi character
\Chi	uppercase greek chi character
\psi	lowercase greek psi character
\Psi	uppercase greek psi character
\omega	lowercase greek omega character
\Omega	uppercase greek omega character
\odot	Sun
\sun	Sun
\mercury	Mercury
\venus	Venus
\earth	Earth
\mars	Mars
\jupiter	Jupiter
\saturn	Saturn
\uranus	Uranus
\neptune	Neptune
\pluto	Pluto
\circ	circ
\textdegree	degree
\int	integral
\pentagon	pentagon
\hexagon	hexagon
\ScissorRight	scissors
\Asterisk	asterisk
\FiveStar	five-point star
\SixStar	six-point star
\leftmoon	left moon
\rightmoon	right moon
\maltese	maltese cross
\rightturn	circular arrow
\smiley	happy face
\eighthnote	eighth note
\hbar	hbar
\pounds	pounds symbol
\pm	plus or minus symbol
\div	division symbol
\times	multiplication symbol
\copyright	copyright symbol
\aa	lowercase a with circle above it
\ae	lowercase ae symbol
\AE	uppercase AE symbol
\clubsuit	club symbol
\heartsuit	heart symbol
\spadesuit	spade symbol
\diamondsuit	diamond symbol
\forall	for all symbol (inverted capital A)
\exists	exists symbol (backwards capital E)
\angle	angle symbol
\neq	not equal
\equiv	equivalent
\approx	approximate
\bullet	bullet
\infty	infinity
\otimes	circle containing x
\oplus	circle containing plus
\leftrightarrow	narrow shaft arrow pointing left and right
\leftarrow	narrow shaft arrow pointing left
\rightarrow	narrow shaft arrow pointing right
\uparrow	narrow shaft arrow pointing up
\downarrow	narrow shaft arrow pointing down
\Leftrightarrow	wide shaft arrow pointing left and right
\Leftarrow	wide shaft arrow pointing left
\Rightarrow	wide shaft arrow pointing right
\Uparrow	wide shaft arrow pointing up
\Downarrow	wide shaft arrow pointing down
\aleph	aleph
\in	in
\notin	not in
\cap	cap
\cup	cup
\supset	superset
\supseteq	superset eq
\subset	subset
\subseteq	subset eq
\leq	less than or equal
\geq	greater than or equal
\propto	propto
\partial	partial
\Im	Im
\Re	Re
\wp	wp
\ldots	ellipsis
\cong	congruent
\diamond	diamond
\langle	langle
\lceil	lceil
\nabla	nabla
\surd	surd
\neg	neg

Thickness

Thickness is a property of objects which display line segments, such as curves, contours, and regions.

Thickness is specified as a floating point value which may range from 0.5 to 10.0. Screen displays typically represent line thickness as integer values, but floating point specifications are supported for postscript output. While a value of 0.5 and 1 will appear differently in postscript output, they will both appear as a thickness of 1 in the screen display.

Tick Format

Tick formats allow the user to specify the appearance of axis tick labels. The syntax is similar to that of the C printf format strings: "%<qualifier><format>". Text may be included before or after the qualifier.

# Python
   set_axis("ay1",["tickformat","distance %2.1f km"])

% S-Lang
   set_axis("ay1",{"tickformat","distance %2.1f km"});

Tick formats do not support latex conventions.

The following tick formats are supported:

Tick Mode

Tick modes control the placement of tick marks on an axis. There are different modes which may be utilized. Two of the modes automatically determine tick locations based on the values of the data being plotted. The other three use data-independent values.

Changing the values associated with interval, count, or arbitrary tick marks (majortick.interval, majortick.count, and arbitrary tick positions respectively) will result in the axis automatically changing to the appropriate tick mode.

Changing the tick mode may result in a change in the range of one or more axes.

The following tick modes are supported; details on each follow the table.

• Arbitrary tick mode allows the user to specify the exact locations of the tick marks. ASCII text values may be used instead of numeric values, but there must be 1-to-1 mapping between the arbitrary locations and the specified text.
• Count tick mode allows the user to request a number of tick marks to be displayed. ChIPS will attempt to place the requested number of tick marks at "nice" locations. If nice placement can not be achieved with the specified numer of tick marks, ChIPS will display more or less than the requested number. The "majortick.count" value serves as a guideline for count mode.
• Interval tick mode uses a configurable interval value to determine where to place the tick marks. Tick locations are calculated at the specified interval using 0 as a reference point. For instance, a majortick.interval of 7 would place ticks at 7, 14, 21, 28, 35, ... If the range of the data is smaller than the interval, zero or one tick marks will be displayed.
• Limits and nice tick modes automatically adjust the tick mark locations based on the range of the data (or user specified limits). These modes attempt to position the ticks using intervals that are generally factors of 1, 2, 5, 10 such that approximate four to six tick marks are displayed. Nice mode starts and ends on tick marks, while limits mode provides a pad factor so that the tick marks are buffered by a configurable padding percentage.

Tick Style

Tick styles specify how the tick marks are placed on an axis. They may centered on the axis such that they extend evenly above and below the axis. They may also extend out in only one direction from the axis. In the latter case, the location of the axis determines which way the tick marks should extend.

The direction of the tick styles refer to axes that are specified in Plot Normalized or Data coordinates. Axes that are specified in other coordinates may behave differently. For instance, an axis specified in Frame Normalized coordinates has the reference point at the center of the frame rather than the center of the plot when determining the direction of "inside" or "outside".

The following tick values are supported: