Maya Python: mel.eval(invertSelection;) not working

Question

Pretty much exactly as the title states, I've got a simple python script in Maya that isn't functioning.

import maya.cmds as cmds
import maya.mel as mel

def createCylinder():
    # Check if cylinder "trunkCylinder" exists. Delete it
    if cmds.objExists("trunkCylinder"):
        cmds.delete("trunkCylinder")
    # Create a new cylinder called "trunkCylinder"
    cmds.polyCylinder(axis=(0,1,0), height=1, name="trunkCylinder" )
    # Clear the selection, then select the cap and invert the selection.
    cmds.select(clear=True)
    cmds.select("trunkCylinder.f[21]", replace=True)
    invertedSel = mel.eval("invertSelection;")
    print str(invertedSel)
    # ^^ Prints: None ^^
    # End result is nothing is selected

createCylinder()

I expected Maya to print a list of all faces on trunkCylinder except f[21] and to inverse the selection in the viewport. Instead, it returns None and deselects f[21]. Does anyone see a mistake in my code, or am I using invertSelection incorrectly?

Fortunately I can just select f[0:20] as a workaround, or even get a list of the faces and compare it to my list of faces, removing anything that is on both lists. However I can already envision situations where getting invertSelection to work would save me a lot of time. Any help here would be appreciated.

Answer 1

The following Python script is definitely works. You should try it)). Asterisk is used for selection of all the other faces in array, along with toggle flag, that inverted a selection for you.

import maya.cmds as cmds

def createCylinder():
    if cmds.objExists("trunkCylinder"):
        cmds.delete("trunkCylinder")
    cmds.polyCylinder(axis=(0,1,0), height=1, name="trunkCylinder")
    cmds.select(clear=True)
    cmds.select("trunkCylinder.f[21]")
    cmds.select("trunkCylinder.f[*]", tgl=True)

createCylinder()