# Trivial Producer Scalars not Visible? (Part of increasing understanding of VTK + Paraview scripting)
**URL:** https://discourse.paraview.org/t/trivial-producer-scalars-not-visible-part-of-increasing-understanding-of-vtk-paraview-scripting/10216
**Category:** ParaView Support
**Tags:** python, vtk
**Created:** [August 29, 2022, 9:20pm UTC](https://discourse.paraview.org/t/trivial-producer-scalars-not-visible-part-of-increasing-understanding-of-vtk-paraview-scripting/10216 "2022-08-29T21:20:24Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Devin\_Richard\_Bayly](https://discourse.paraview.org/u/Devin_Richard_Bayly)
#### Post date: [August 29, 2022, 9:20pm UTC](https://discourse.paraview.org/t/trivial-producer-scalars-not-visible-part-of-increasing-understanding-of-vtk-paraview-scripting/10216/1 "2022-08-29T21:20:25Z")
Hi there,
I’m trying to improve my understanding of both paraview and vtk’s python module by generating small point sets and viewing them in paraview using the Trivial Producer. I succeed in getting points drawn to the screen with this code when I use `Run Script` in paraview, but there’s no clear way to see the scalar data set on the points.
```auto
import numpy as np
from paraview.simple import *
import paraview.vtk as vtk
from paraview.vtk.numpy_interface import dataset_adapter as dsa
import paraview.vtk.util.numpy_support as vnp
node = np.array(
[[0.0, 0.0, 0.0],
[1.0, 0.0, 0.0],
[1.0, 1.0, 0.0],
[0.0, 1.0, 0.0]], dtype=np.float)
NC = cell.shape[0]
points = vtk.vtkPoints()
points.SetData(vnp.numpy_to_vtk(node))
vpoly = vtk.vtkPolyData()
vpoly.SetPoints(points)
# create scalars
s = vtk.vtkFloatArray()
s.InsertTuple1(0,20.0)
s.InsertTuple1(1,30.0)
s.InsertTuple1(2,50.0)
s.InsertTuple1(3,50.0)
vcells = vtk.vtkCellArray()
for i in range(node.shape[0]):
vcells.InsertNextCell(1)
vcells.InsertCellPoint(i)
vpoly.SetVerts(vcells)
vpoly.GetPointData().SetScalars(s)
# how to put uGrid into the following codes
view = GetActiveViewOrCreate('RenderView')
# create a trivial producer to bridge between the VTK object and ParaView
tp = TrivialProducer()
tp.GetClientSideObject().SetOutput(vpoly)
dispaly = Show(tp)
#Interact()
```
Funnily enough if I use the vtp extractor then I can open a resulting vtp file and see the scalar data, but I’d prefer not to do those several extra steps just to view some small changes in the values I write in the python script.
Here’s what things look like in paraview. I’m unsure if the error that comes up is related to the missing data displayed
So the question is, how can I use trivial producer to show scalar data on a vtkPolyData object I’ve written from scratch? In a larger sense this question is also asking “what is the preferred way to use vtk and paraview scripting together?”
Thanks for any support on this matter!
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [August 30, 2022, 12:47am UTC](https://discourse.paraview.org/t/trivial-producer-scalars-not-visible-part-of-increasing-understanding-of-vtk-paraview-scripting/10216/2 "2022-08-30T00:47:33Z")
> the error
Name your array
> the question is, how can I use trivial producer to show scalar data on a vtkPolyData object I’ve written from scratch?
Yes, but only in built-in mode, not in server mode.
> In a larger sense this question is also asking “what is the preferred way to use vtk and paraview scripting together?”
Programmable source/Filter
---
### Author:  [@Devin\_Richard\_Bayly](https://discourse.paraview.org/u/Devin_Richard_Bayly)
#### Post date: [August 30, 2022, 9:00pm UTC](https://discourse.paraview.org/t/trivial-producer-scalars-not-visible-part-of-increasing-understanding-of-vtk-paraview-scripting/10216/3 "2022-08-30T21:00:53Z")
Thank you for the concise yet comprehensive run through of my questions!
Oh woops, yes I was totally expecting something like `_Scalars` by default but that was wrong. Sure enough adding `s.SetName("test")` did the trick.
Great I’ll make sure I understand those better as they are the preferred route to make use of python vtk within paraview.
Cheers