Getting Started

Learn how to get started using the Python API.

Launch the Python Console in MotionView

  1. Launch a new MotionView session and right-click in the Model Browser.
  2. Click on the Python Window option.

    Figure 1.
    The MV Python Console is launched.

    Figure 2.

Python Console Conventions

Figure 3.

Importing mview Package

In order to create, modify, and interact with the MotionView modeling entities through python, the mview package needs to be imported first.
>>> from hw import mview

Creating and Modifying Entities

Try out the following commands in the python console:
Creating Entities
 >>> from hw import mview
# import mview package
>>> p1 = mview.Point(name="p_0", x=1, y=4, z=3)
# creates a point
>>> b1 = mview.Body(name="Body1")
# creates a body
>>> m1 = mview.Marker(name="Marker1",body=b1,origin=p1)
# creates a marker at origin p1 and on body b1
Accessing Attribute Values
The dot operator (.) is used to "get" or access class attribute values. You can also use a getValue function to do the same. These values can be used in other python expressions. The examples below illustrates this.
>>> p = mview.Point(name="p_0", x=1, y=4, z=-2)
# Create a point
>>> p.x
# Get x coordinate of a point
# Get variable name of the point
>>> b = mview.Body(name="b_0", mass=1000, ixx=200, iyy=300, izz=400, cg=p)
# Create a body with its cg at location of point p1
   <hw.mview.mbd.Point.Point object at 0x00000162DEB8E940>
# Get value of the cg, returns the handle of the point it points to
# Get the name of this point
Modifying Attribute Values
In a similar way, you can modify attribute values through dot notation or a setValue function.
>>> p.y = 2
>>> p.y
# Modify the "y" coordinate value of point "p_0" created previously
>>> p.setValue('z', 12)
 >>> p.z
# Use setValue function to change "z" coordinate value. Returns True on successfully setting the value
>>>  = "P_Global_Origin"
# Assign the Global Origin to the "cg" of body "b_0"
>>> p.setValues(x=11, y=22, z=33)
>>> p.x
>>> p.y
>>> p.z
# Use setValues function to change multiple values at a time
Note: While assigning value to a property which expects an entity reference, for example the cg property of a body, either the full variable name of the entity or the python handle of that entity can be used.
Assign Parametric Values to Attributes
To assign values which are dependent on properties of other entities, use the full varname of that property as below.
>>> p1 = mview.Point( name='p_1', x=3, y=3, z=3)
>>> p2 = mview.Point( name='p_2', x=2)
>>> p2.x = "p_1.x"
>>> p2.x
# x coordinate of p2 is expressed in terms of x coordinate of Point p_1 (Parametric expression is given as a string)
>>> p1.x = 12
>>> p2.x
# Changing x coordinate of p1 changes x coordinate of p2
Getting Python Handles of Entities
To get the python handle to the entity from its variable name use the function getObjectFromPath().
>>> from hw import mview
   >>> p = mview.getObjectFromPath("MODEL.System_1.Point_1")
   >>> p.parent
   <hw.mview.mbd.System.System object at 0x00000201C9DF0128>
# get the handle of a point "Point_1" in "System_1" which is already created
You can also get the handle of an entity using the getModel() function which gets the model.
>>> p1 = mview.getModel().System_1.Point_1
# get the handle of a point "Point_1" in "System_1" which is already created using getModel() function

Saving, Opening, and Exporting Models

To save a model as an mdl file, use the writeFile method on the mview class (see the example below):
>>> from hw import mview
>>> mview.writeFile(r"C:/Temp/example.mdl")
To export a model to a MotionSolve xml file, use the writeFile function:
>>> mview.writeFile(r"C:/Temp/example.xml")
To open an mdl file or a python script, use the readFile function:
>>> mview.readFile(r"C:/Temp/example.mdl")
Use the runSolverScript function to run a solver script:
>>> mview.runSolverScript(r"C:\Altair\Examples\gearpair1.xml")

Python Console Tips and Tricks

  1. The console can be cleared using the shortcut "Ctrl+L" or %clear.
  2. Try <Tab> for an auto-complete suggestion for a function or property name.
  3. Use <F1> for bubble help for an entity/property.

Running Python Scripts

A python script can be executed by any of the following three methods:
  1. Right-click in the Model Browser and select Python Script to browse for a python file containing the script.


  2. Use the standard python function in the console.
    >>> exec(open(r"C:/Users/username/").read())


  3. Use %run command in the console.
    >>> %run C:/Temp/Examples/ 1
    Note: %run is not a standard python command.

Command Logging

You can log the commands you type in the Python console as follows:
  1. Go to Tools > Options > Build Model.
  2. Click on the Enable python window command logging check box.
  3. Provide a log file to save.