SimBiology.Unit

User-defined unit

Description

The SimBiology.Unit object holds information about user-defined units. To make a custom unit, create the unit object and add the unit to the library using the sbioaddtolibrary function. Use the Composition property to specify the composition of your units.

Use dot notation to query the object properties or change properties that are not read-only. You can also use the get and set commands.

You can also customize the units in the SimBiology Model Builder app. For details, see SimBiology Model Component Libraries.

Creation

Use sbiounit to create a custom unit.

Properties

Composition — Unit composition

empty character array (default) | character vector | string scalar

Unit composition, specified as a character vector or string scalar.

The Composition property holds the composition of a unit object. The Composition property shows the combination of base and derived units that defines the unit. For example, molarity is the name of the unit and the composition is mole/liter. Base units are the set of units used to define all unit quantity equations. Derived units are defined using base units or mixtures of base and derived units.

Valid physical quantities for reaction rates are amount/time, mass/time, or concentration/time.

Example: "mole/liter"

Data Types: char | string

Multiplier — Relationship between defined unit and base unit

1 (default) | nonzero numeric scalar

Relationship between the defined unit and base unit, specified as a nonzero numeric scalar.

Multiplier defines such a relationship as a product between the base unit and a numeric value (that is, a multiplier). For example, in 1 mole = 6.0221e23*molecule, the Multiplier value is 6.0221e23.

Example: 10

Data Types: double

Name — SimBiology.Unit object name

character vector | string

SimBiology.Unit object name, specified as a character vector or string.

For details on requirements and recommendations for naming SimBiology^® components, see Guidelines for Naming Model Components.

Data Types: char | string

Notes — Additional information

empty character array (default) | character vector | string

Additional information that you can add for SimBiology.Unit, specified as a character vector or string.

Data Types: char | string

Parent — Parent object

SimBiology.Model object | SimBiology.KineticLaw object

This property is read-only.

Parent object, specified as a SimBiology.Model or SimBiology.KineticLaw object.

Parent — Parent object

[] | root object

This property is read-only.

Parent object, specified as [] or root object. The default property value is [] until you add the SimBiology.Unit object to the library. Then the value becomes a root object upon addition to the library.

Tag — Object label

empty character array (default) | character vector | string

Object label, specified as a character vector or string.

Tip

Use this property to group objects and then use sbioselect to retrieve. For example, use the Tag property of reaction objects to group synthesis or degradation reactions. You can then retrieve all synthesis reactions using sbioselect. Similarly, for species objects you can enter and store classification information, for example, membrane protein, transcription factor, enzyme classifications, or whether a species is an independent variable. You can also enter the full form of the name of the species.

Data Types: char | string

Type — Object type

'unit' (default)

This property is read-only.

Object type, specified as 'unit'. When you create a SimBiology object, the value of Type is automatically defined.

Data Types: char

UserData — Data to associate with object

scalar | vector | string | ...

Data to associate with the object, specified as a numeric scalar, vector, string, or any other MATLAB data type.

The object does not use this data directly, but you can access it using dot notation or get.

Object Functions

delete	Delete SimBiology object
display	Display summary of SimBiology object
findUsages	Find out how a unit or unit prefix is used
get	Get SimBiology object properties
rename	Rename SimBiology model component and update expressions
set	Set SimBiology object properties

Examples

Define a Custom Unit in SimBiology

Create a user-defined unit called usermole, whose Composition property is molecule and Multiplier property is 6.0221e23.

unitObj = sbiounit('usermole','molecule',6.0221e23); 

Add the unit to the user-defined library.

sbioaddtolibrary(unitObj);

Query the Multiplier property.

unitObj.Multiplier

ans = 
6.0221e+23

Create a Custom Unit Prefix and Add to Library

Create a unit prefix peta with the exponent value of 15.

petaPrefix = sbiounitprefix("peta",15);

Add the unit prefix to the library.

sbioaddtolibrary(petaPrefix);

Check the library of unit prefixes. Note that peta has been added as a user-defined unit prefix.

sbioshowunitprefixes

ans = 
   SimBiology Unit Prefix Array

   Index:    Library:       Name:    Exponent:
   1         BuiltIn        centi    -2       
   2         BuiltIn        deci     -1       
   3         BuiltIn        deka     1        
   4         BuiltIn        femto    -15      
   5         BuiltIn        giga     9        
   6         BuiltIn        hecto    2        
   7         BuiltIn        kilo     3        
   8         BuiltIn        mega     6        
   9         BuiltIn        micro    -6       
   10        BuiltIn        milli    -3       
   11        BuiltIn        nano     -9       
   12        UserDefined    peta     15       
   13        BuiltIn        pico     -12      
   14        BuiltIn        tera     12       

Alternatively, you can use sbiowhos or the root object.

sbiowhos -userdefined -unitprefix

   SimBiology UserDefined Unit Prefixes
           
   Index:  Name:           Multiplier:              
   1       peta            1000000000000000         

rootObj = sbioroot;
rootObj.UserDefinedLibrary.UnitPrefixes

ans = 
   SimBiology Unit Prefix Array

   Index:    Library:       Name:    Exponent:
   1         UserDefined    peta     15       

Version History

Introduced in R2008a

R2024a: Having duplicate model component names is no longer allowed

• When you load a model that contains duplicate names, SimBiology automatically updates those names. SimBiology disambiguates the duplicate names by adding a suffix "_N", where N is the first positive integer that results in a unique name. If there is an existing suffix, N will be incremented from that suffix. For example, if there are two model components named x_3, the function updates one of the names to x_4. If the existing suffix has leading zeros, the function omits the zeros in the new name. For instance, if x_003 is a duplicate name, it gets renamed to x_4. However, the function assumes that names with leading zeros and without leading zeros are different. For instance, x_005 and x_5 are considered to be different names.

• SimBiology issues an error if multiple model components (model, compartment, species, parameter, reaction, rule, event, observable, dose, and variant) have the same name. Within a single model, these components are required to have unique names even when they are of different types with the following two exceptions:

  • Species in different compartments can have the same name.

  • Parameters can have the same name if they are scoped to different parents. Specifically, you can use the same name for a model-scoped parameter and reaction-scoped parameters, where each reaction-scoped parameter belongs to a different reaction.

  For details on how to reference model component names in expressions, see Guidelines for Referencing Names in Expressions.

R2022b: Having duplicate model component names issues a warning

SimBiology issues a warning if multiple model components have the same name.

R2022a: Having duplicate model component names will not be allowed in a future release

SimBiology will not allow you to have duplicate names for model components within a model.