# Python example code for splineWidget.GetSummedLength
**URL:** https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529
**Category:** Support
**Created:** [December 30, 2021, 1:01pm UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529 "2021-12-30T13:01:04Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Dgg820502](https://discourse.vtk.org/u/Dgg820502)
#### Post date: [December 30, 2021, 1:01pm UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/1 "2021-12-30T13:01:04Z")
I am trying use splineWidget.GetSummedLength() to get the length of spline, but I always get the same length data no matter how I moved spline around.
Please let know if there is example code for splineWidget.GetSummedLength?
Many thanks in advance.
David.
The following is the code:
######################################################
splineWidget =vtk.vtkSplineWidget()
splineWidget.SetInteractor(iren)
splineWidget.AddObserver(“EndInteractionEvent”, my\_call\_back)
##############################################
iren.Initialize()
renWin.Render()
distanceWidget.On()
angleWidget.On()
bidimensionalWidget.On()
splineWidget.On()
# Initialize the event loop and then start it.
iren.Start()
def my\_call\_back(pWidget,ev):
```
if (pWidget):
print(pWidget.GetClassName(), "Event Id:", ev)
if(ev == "EndInteractionEvent"):
splineWidget = vtk.vtkSplineWidget()
splineWidget.SetResolution(10)
length = splineWidget.GetSummedLength()
print("spline length = "+str(length))
####################################
```
show(‘C:/results/interpolcontour/s.mhd’)
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [December 31, 2021, 6:17am UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/2 "2021-12-31T06:17:06Z")
It looks like you are creating a new vtkSplineWidget every time it’s called that’s why the length is the same.
I have just written an example [SplineWidget](https://kitware.github.io/vtk-examples/site/Python/Widgets/SplineWidget/) that shows you how to implement a callback. I’ll probably improve it and write a C++ example in the next few days.
Have a look at the example.
---
### Author:  [@Dgg820502](https://discourse.vtk.org/u/Dgg820502)
#### Post date: [December 31, 2021, 9:31am UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/3 "2021-12-31T09:31:59Z")
Dear Andrew,
Very appreciate for your generous help.
I am implementing your code into mine.
I will let you know any outcomes.
David.
---
### Author:  [@Dgg820502](https://discourse.vtk.org/u/Dgg820502)
#### Post date: [December 31, 2021, 9:52am UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/4 "2021-12-31T09:52:10Z")
Dear Andrew,
Your code is working perfectly.
I can get updated spline length.
Many thanks.
David.
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [December 31, 2021, 10:12am UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/5 "2021-12-31T10:12:46Z")
Happy New Year
Andrew Maclean
---
### Author:  [@Dgg820502](https://discourse.vtk.org/u/Dgg820502)
#### Post date: [December 31, 2021, 11:54am UTC](https://discourse.vtk.org/t/python-example-code-for-splinewidget-getsummedlength/7529/6 "2021-12-31T11:54:03Z")
The same wishes for you in New year.
Be safe and happy.
David