Usage:
( rangecolor | rangecolour ) attr_name[,a][,r][,s][,v][,l][,la][,lr] [key] value1 color1 value2 color2 [... valueN colorN] atom-spec

Rangecolor shows the values of an attribute such as B-factor or hydrophobicity with color gradations. The attribute is specified by name (attr_name) and must be numerical (see examples). The related tool Render by Attribute provides a graphical interface for coloring by attribute values. See also: color, colorkey, rainbow, coulombic, scolor, transparency, defattr, setattr, msc, Render by Attribute, examples on the Chimera website: Mapping Sequence Conservation, Coloring by NMR Chemical Shift Perturbation

At least two value/color pairs must be supplied. Pairs do not need to be ordered by value. Values (value1, value2, etc.) can be specified directly or with the special words:

A pair specified with novalue does not contribute toward the minimum of two pairs because the corresponding color is not involved in any ranges; it is only used to color items with no value for the specified attribute (for example, nucleic acid residues do not have kdHydrophobicity values). When an atom attribute is used to color ribbons, the ribbon segment for each residue is colored according to the average of the values for atoms in the residue. In all cases, the reported min, mid, and max values describe the original attribute rather than any derived quantity such as an average.

Each color name (color1, color2, etc.) can be any color name that specifies a single color.

The atom-spec indicates which atoms (and/or associated labels, surfaces, or ribbon) are to be colored. If no atom-spec is given, all atoms (and/or their associated labels, surfaces, or ribbon) are affected.

While atom-spec indicates the scope of coloring, one or more specifiers can be used to indicate which types of items should be colored:

• a (or b) - atoms (and normally, bond halves are colored to match the flanking atoms)
• r - ribbons
• s - molecular surfaces
• v - VDW surfaces
• l - atom and residue labels
• la (or al) - atom labels
• lr (or rl) - residue labels

The key option brings up the Color Key tool, filled in with the appropriate colors and values, and set to Use mouse for key placement for creating/positioning the color key in the graphics window. The mouse setting can be toggled to allow moving models with the mouse.

In Chimera, visible color is determined by a hierarchy. Rangecolor sets atom, atom label, and surface colors at the atom level, and ribbon and residue label colors at the residue level.

Examples:

rangecol bfactor,s key min blue 20 white 40 red

range kdHydrophobicity min lime green max orange novalue magenta