Python Script Unit Operation¶

Represents a Python Script Unit Operation that executes user-supplied Python code (IronPython or Python.NET) as part of the flowsheet calculation sequence.

DWSIM.UnitOperations.UnitOperations.CustomUO
Assembly DWSIM.UnitOperations.dll · Object ← BaseClass ← UnitOpBaseClass ← CustomUO

At a glance¶

Python Script Unit Operation in the example flowsheet

Port	Index	Connected in the example
Inlet, material	`0`	Feed
Inlet, material	`1`
Inlet, material	`2`
Inlet, energy	`3`
Inlet, material	`4`
Inlet, material	`5`
Inlet, material	`6`
Outlet, material	`0`	Product
Outlet, material	`1`
Outlet, material	`2`
Outlet, energy	`3`	Duty
Outlet, material	`4`
Outlet, material	`5`
Outlet, material	`6`

Example¶

This code runs on every build of this site, and the output below is what it printed.

Python

    fs = (Flowsheet.Create("ScriptUOExample")
          .WithCompounds("N-hexane", "N-heptane")
          .WithPropertyPackage(PropertyPackages.PengRobinson))

    feed = (fs.AddMaterialStream("Feed")
            .At(Q.Celsius(25.0), Q.Bar(2.0))
            .SetCompoundMassFlow("N-hexane", 0.9)       # kg/s
            .SetCompoundMassFlow("N-heptane", 0.6))
    product = fs.AddMaterialStream("Product")
    duty = fs.AddEnergyStream("Duty")

    # The script runs in IronPython. ims1..ims6 and oms1..oms6 are the material streams on
    # ports 0-2 and 4-6, ies1 and oes1 the energy streams on port 3. Every input variable
    # becomes a script variable, and every number left in the script becomes an output.
    script = """
oms1.Assign(ims1)
oms1.SetTemperature(ims1.GetTemperature() + DeltaT)
oms1.SetFlashSpec("PT")
oms1.Calculate()
Q_kW = ims1.GetMassFlow() * (oms1.GetMassEnthalpy() - ims1.GetMassEnthalpy())
oes1.EnergyFlow = Q_kW
"""

    uo = (fs.AddUnitOperation(ObjectType.CustomUO, "SCRIPT-1")
          .ConnectFeed(feed, 0)
          .ConnectProduct(product, 0))
    # the duty leaves through outlet port 3
    uo.ConnectEnergyProduct(duty, 3)
    s = uo.Object.__implementation__             # the PythonScriptUO behind the generic builder
    s.ScriptText = script
    s.InputVariables["DeltaT"] = 40.0            # K

    fs.AutoLayout()
    fs.Solve()

    print(f"Outlet T          = {product.TemperatureK - 273.15:.2f} C")
    print(f"Duty (script)     = {s.OutputVariables['Q_kW']:.2f} kW")
    print(f"Energy stream     = {duty.Object.EnergyFlow:.2f} kW")
    print(f"Mean cp           = {s.OutputVariables['Q_kW'] / (1.5 * 40.0):.3f} kJ/(kg.K)")

Output

Outlet T          = 65.00 C
Duty (script)     = 135.84 kW
Energy stream     = 135.84 kW
Mean cp           = 2.264 kJ/(kg.K)

DWSIM 10.2.11.0, generated 2026-10-08.

Properties¶

IDs accepted by GetPropertyValue, SetPropertyValue, the sensitivity analysis, the optimizer, the Adjust block and dynamic events. Units are SI; pass another unit system to GetPropertyValue to get them converted.

ID	Name	Unit (SI)	Input
`DeltaT`	Temperature Difference		yes
`Q_kW`			result

Learn more¶

User guide
- Custom Unit Operation

API members¶

Public members declared by this class. Inherited members are documented on the base classes.

Constructors¶

CustomUO(): Initializes a new default instance.

Initializes a new default instance.

C#VB.NET

public CustomUO()

Public Sub New()

CustomUO(string, string): Initializes a new instance with a name and description.

Initializes a new instance with a name and description.

Parameter	Type	Description
`name`	`String`
`description`	`String`

C#VB.NET

public CustomUO(string name, string description)

Public Sub New(name As String, description As String)

Properties¶

EmbeddedImageData: Gets or sets the Base-64 encoded embedded image data for a custom icon.

Gets or sets the Base-64 encoded embedded image data for a custom icon.

C#VB.NET

public string EmbeddedImageData { get; set; }

Public Property EmbeddedImageData As String

ExecutionEngine: Gets or sets the Python execution engine (IronPython or Python.NET).

Gets or sets the Python execution engine (IronPython or Python.NET).

C#VB.NET

public CustomUO.PythonExecutionEngine ExecutionEngine { get; set; }

Public Property ExecutionEngine As CustomUO.PythonExecutionEngine

FontName: Gets or sets the font name used in the script editor.

Gets or sets the font name used in the script editor.

C#VB.NET

public string FontName { get; set; }

Public Property FontName As String

FontSize: Gets or sets the font size used in the script editor.

Gets or sets the font size used in the script editor.

C#VB.NET

public int FontSize { get; set; }

Public Property FontSize As Integer

HasPropertiesForDynamicMode: Gets a value indicating this unit operation has no specific dynamic-mode properties.

Gets a value indicating this unit operation has no specific dynamic-mode properties.

C#VB.NET

public override bool HasPropertiesForDynamicMode { get; }

Public Overrides ReadOnly Property HasPropertiesForDynamicMode As Boolean

HighlightSpaces: Gets or sets whether spaces are highlighted in the script editor.

Gets or sets whether spaces are highlighted in the script editor.

C#VB.NET

public bool HighlightSpaces { get; set; }

Public Property HighlightSpaces As Boolean

HighlightTabs: Gets or sets whether tabs are highlighted in the script editor.

Gets or sets whether tabs are highlighted in the script editor.

C#VB.NET

public bool HighlightTabs { get; set; }

Public Property HighlightTabs As Boolean

Includes: Gets or sets the list of additional Python script files to include.

Gets or sets the list of additional Python script files to include.

C#VB.NET

public string[] Includes { get; set; }

Public Property Includes As String()

InputStringVariables: Gets or sets the dictionary of string-typed input variables exposed to the script.

Gets or sets the dictionary of string-typed input variables exposed to the script.

C#VB.NET

public Dictionary<string, string> InputStringVariables { get; set; }

Public Property InputStringVariables As Dictionary(Of String, String)

InputVariables: Gets or sets the dictionary of numeric input variables exposed to the script.

Gets or sets the dictionary of numeric input variables exposed to the script.

C#VB.NET

public Dictionary<string, double> InputVariables { get; set; }

Public Property InputVariables As Dictionary(Of String, Double)

MobileCompatible: Gets a value indicating whether this unit operation is compatible with mobile interfaces.

Gets a value indicating whether this unit operation is compatible with mobile interfaces.

C#VB.NET

public override bool MobileCompatible { get; }

Public Overrides ReadOnly Property MobileCompatible As Boolean

ObjectClass: Gets or sets the simulation object class category (UserModels).

Gets or sets the simulation object class category (UserModels).

C#VB.NET

public override SimulationObjectClass ObjectClass { get; set; }

Public Overrides Property ObjectClass As SimulationObjectClass

OutputVariables: Gets or sets the dictionary of numeric output variables produced by the script.

Gets or sets the dictionary of numeric output variables produced by the script.

C#VB.NET

public Dictionary<string, double> OutputVariables { get; set; }

Public Property OutputVariables As Dictionary(Of String, Double)

ScriptText: Gets or sets the Python script text to execute during calculation.

Gets or sets the Python script text to execute during calculation.

C#VB.NET

public string ScriptText { get; set; }

Public Property ScriptText As String

SupportsDynamicMode: Gets a value indicating this unit operation supports dynamic mode.

Gets a value indicating this unit operation supports dynamic mode.

C#VB.NET

public override bool SupportsDynamicMode { get; }

Public Overrides ReadOnly Property SupportsDynamicMode As Boolean

UseEmbeddedImage: Gets or sets whether the embedded image is used as the graphic object icon.

Gets or sets whether the embedded image is used as the graphic object icon.

C#VB.NET

public bool UseEmbeddedImage { get; set; }

Public Property UseEmbeddedImage As Boolean

Methods¶

Calculate(object): Executes the Python script, passing flowsheet objects and variables into the scope.

Executes the Python script, passing flowsheet objects and variables into the scope.

Parameter	Type	Description
`args`	`Object`

C#VB.NET

public override void Calculate(object args = null)

Public Overrides Sub Calculate(args As Object = Nothing)

CloneXML(): Creates a deep copy via XML serialization.

Creates a deep copy via XML serialization.

C#VB.NET

public override object CloneXML()

Public Overrides Function CloneXML() As Object

CloseEditForm(): Closes and disposes the editing form.

Closes and disposes the editing form.

C#VB.NET

public override void CloseEditForm()

Public Overrides Sub CloseEditForm()

DeCalculate(): Clears all calculated results.

Clears all calculated results.

C#VB.NET

public override void DeCalculate()

Public Overrides Sub DeCalculate()

DisplayEditForm(): Opens or activates the editing form.

Opens or activates the editing form.

C#VB.NET

public override void DisplayEditForm()

Public Overrides Sub DisplayEditForm()

DisplayScriptEditorForm(): Opens the script editor window.

Opens the script editor window. Does nothing where the WinForms editors are not built.

C#VB.NET

public void DisplayScriptEditorForm()

Public Sub DisplayScriptEditorForm()

GetDisplayDescription(): Returns the localised display description.

Returns the localised display description.

C#VB.NET

public override string GetDisplayDescription()

Public Overrides Function GetDisplayDescription() As String

GetDisplayName(): Returns the localised display name.

Returns the localised display name.

C#VB.NET

public override string GetDisplayName()

Public Overrides Function GetDisplayName() As String

GetIconBitmapBytes(): Returns the icon bitmap as a byte array.

Returns the icon bitmap as a byte array.

C#VB.NET

public override byte[] GetIconBitmapBytes()

Public Overrides Function GetIconBitmapBytes() As Byte()

GetProperties(PropertyType): Returns an array of property identifiers for the specified property type.

Returns an array of property identifiers for the specified property type.

Parameter	Type	Description
`proptype`	`PropertyType`

C#VB.NET

public override string[] GetProperties(PropertyType proptype)

Public Overrides Function GetProperties(proptype As PropertyType) As String()

GetPropertyUnit(string, IUnitsOfMeasure): Returns the unit string for the specified property.

Returns the unit string for the specified property.

Parameter	Type	Description
`prop`	`String`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override string GetPropertyUnit(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyUnit(prop As String, su As IUnitsOfMeasure = Nothing) As String

GetPropertyValue(string, IUnitsOfMeasure): Returns the value of the specified property.

Returns the value of the specified property.

Parameter	Type	Description
`prop`	`String`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override object GetPropertyValue(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyValue(prop As String, su As IUnitsOfMeasure = Nothing) As Object

GetReport(IUnitsOfMeasure, CultureInfo, string): Generates a plain-text report of the unit operation results.

Generates a plain-text report of the unit operation results.

Parameter	Type	Description
`su`	`IUnitsOfMeasure`
`ci`	`CultureInfo`
`numberformat`	`String`

C#VB.NET

public override string GetReport(IUnitsOfMeasure su, CultureInfo ci, string numberformat)

Public Overrides Function GetReport(su As IUnitsOfMeasure, ci As CultureInfo, numberformat As String) As String

LoadData(List<XElement>): Restores the unit operation state from XML, including variable dictionaries.

Restores the unit operation state from XML, including variable dictionaries.

Parameter	Type	Description
`data`	`List<XElement>`

C#VB.NET

public override bool LoadData(List<XElement> data)

Public Overrides Function LoadData(data As List(Of XElement)) As Boolean

RunDynamicModel(): Executes the script in dynamic simulation mode.

Executes the script in dynamic simulation mode.

C#VB.NET

public override void RunDynamicModel()

Public Overrides Sub RunDynamicModel()

SaveData(): Serializes the unit operation state to XML, including variable dictionaries.

Serializes the unit operation state to XML, including variable dictionaries.

C#VB.NET

public override List<XElement> SaveData()

Public Overrides Function SaveData() As List(Of XElement)

SetPropertyValue(string, object, IUnitsOfMeasure): Sets the value of the specified property.

Sets the value of the specified property.

Parameter	Type	Description
`prop`	`String`
`propval`	`Object`
`su`	`IUnitsOfMeasure`

C#VB.NET

public override bool SetPropertyValue(string prop, object propval, IUnitsOfMeasure su = null)

Public Overrides Function SetPropertyValue(prop As String, propval As Object, su As IUnitsOfMeasure = Nothing) As Boolean

UpdateEditForm(): Refreshes the editing form with updated data.

Refreshes the editing form with updated data.

C#VB.NET

public override void UpdateEditForm()

Public Overrides Sub UpdateEditForm()

Validate(): Validates the unit operation configuration.

Validates the unit operation configuration.

C#VB.NET

public override void Validate()

Public Overrides Sub Validate()

Fields¶

f: The classic (WinForms) editor window open for this unit operation, if any.

The classic (WinForms) editor window open for this unit operation, if any. Not saved with the flowsheet.

C#VB.NET

public object f

Public f As Object

fs: Reserved handle for a script editor window; not assigned or read by the current code.

Reserved handle for a script editor window; not assigned or read by the current code. Not saved with the flowsheet.

C#VB.NET

public object fs

Public fs As Object

fsmono: Reserved handle for a script editor window on Mono; not assigned or read by the current code.

Reserved handle for a script editor window on Mono; not assigned or read by the current code. Not saved with the flowsheet.

C#VB.NET

public object fsmono

Public fsmono As Object