# using "find data" aka "extract selection" with python scripting
**URL:** https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562
**Category:** ParaView Support
**Tags:** python
**Created:** [September 12, 2018, 9:41am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562 "2018-09-12T09:41:59Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@J\_R-J](https://discourse.paraview.org/u/J_R-J)
#### Post date: [September 12, 2018, 9:41am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/1 "2018-09-12T09:41:59Z")
Hi there,
I am trying to script some data processing in paraview. Specifically, importing a vti file and using “find data matching various criteria” to find the points which meet my criteria (eg: propertyX \<= 0). When I using “Find Data” and run a python trace however, what I see is the following:
```
# create a new 'Extract Selection'
extractSelection1 = ExtractSelection(Input=dataVTI,
Selection=None)
# show data in view
extractSelection1Display = Show(extractSelection1, renderView1)
# trace defaults for the display properties.
extractSelection1Display.Representation = 'Surface'
extractSelection1Display.ColorArrayName = [None, '']
extractSelection1Display.OSPRayScaleArray = 'geometry'
extractSelection1Display.OSPRayScaleFunction = 'PiecewiseFunction'
extractSelection1Display.SelectOrientationVectors = 'None'
extractSelection1Display.ScaleFactor = 0.21600012183189393
extractSelection1Display.SelectScaleArray = 'None'
extractSelection1Display.GlyphType = 'Arrow'
extractSelection1Display.GlyphTableIndexArray = 'None'
extractSelection1Display.DataAxesGrid = 'GridAxesRepresentation'
extractSelection1Display.PolarAxes = 'PolarAxesRepresentation'
extractSelection1Display.ScalarOpacityUnitDistance = 0.6655801979167395
extractSelection1Display.GaussianRadius = 0.10800006091594697
extractSelection1Display.SetScaleArray = ['POINTS', 'geometry']
extractSelection1Display.ScaleTransferFunction = 'PiecewiseFunction'
extractSelection1Display.OpacityArray = ['POINTS', 'geometry']
extractSelection1Display.OpacityTransferFunction = 'PiecewiseFunction'
# init the 'GridAxesRepresentation' selected for 'DataAxesGrid'
extractSelection1Display.DataAxesGrid.XTitleColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.DataAxesGrid.YTitleColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.DataAxesGrid.ZTitleColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.DataAxesGrid.XLabelColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.DataAxesGrid.YLabelColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.DataAxesGrid.ZLabelColor = [0.3333333333333333, 0.0, 1.0]
# init the 'PolarAxesRepresentation' selected for 'PolarAxes'
extractSelection1Display.PolarAxes.PolarAxisTitleColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.PolarAxes.PolarAxisLabelColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.PolarAxes.LastRadialAxisTextColor = [0.3333333333333333, 0.0, 1.0]
extractSelection1Display.PolarAxes.SecondaryRadialAxesTextColor = [0.3333333333333333, 0.0, 1.0]
# hide data in view
Hide(dataVTI, renderView1)
# update the view to ensure updated data information
renderView1.Update()
```
I do not see anywhere in the python code where propertyX \<= 0 is set. However, in the Properties of the ‘ExtractSelection1’ I see the following:
**Type: Query**
**propertyX \<= 0**
**Elements: Points**
The points are correctly extracted. However I can only do this manually, I have not been able to automate this.
Can someone please explain how to create this extractSelection filter to specify the selection from python?
many thanks in advance
Jesse
---
### Author:  [@wascott](https://discourse.paraview.org/u/wascott)
#### Post date: [September 13, 2018, 8:38pm UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/2 "2018-09-13T20:38:46Z")
Kitware folk? Am I correct that the trace recorder doesn’t trace find data currently?
---
### Author:  [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [September 13, 2018, 10:35pm UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/3 "2018-09-13T22:35:49Z")
> [@wascott](#):
>
> Am I correct that the trace recorder doesn’t trace find data currently?
That is correct: [https://gitlab.kitware.com/paraview/paraview/issues/16836](https://gitlab.kitware.com/paraview/paraview/issues/16836)
---
### Author:  [@J\_R-J](https://discourse.paraview.org/u/J_R-J)
#### Post date: [October 1, 2018, 9:17am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/4 "2018-10-01T09:17:07Z")
I found a way to ‘find data’ using the following python code and get access to the arrays:
```
import vtk
import numpy as np
from vtk.numpy_interface import dataset_adapter as dsa
filename = 'file.vti'
# Read the file
reader = vtk.vtkXMLImageDataReader()
reader.SetFileName(filename)
reader.Update()
reader.PointArrayStatus = ['geometry', 'propertyX', 'propertyY']
usg = dsa.WrapDataObject(reader.GetOutput())
X = usg.PointData['propertyX']
Y = usg.PointData['propertyY']
```
then by using **np.where(X \> 0.0)** I can filter the data I want.
However, I am missing the coordinate data.
In paraview I have access to **‘Point ID’** , **‘Structured Coordinates’** [tuple], **‘geometry’** , **‘propertyX’** , **‘propertyY’**.
After running find data in paraview I have:
**’Point ID’** , **‘vtkOriginalPointIds’** , **‘Points’** [tuple], **‘geometry’** , **‘propertyX’** , **‘propertyY’**.
Could someone please help to access the coordinate data in python and convert these to physical coordinates?
---
### Author:  [@J\_R-J](https://discourse.paraview.org/u/J_R-J)
#### Post date: [October 1, 2018, 10:48am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/5 "2018-10-01T10:48:54Z")
In case someone needs this in the future: (this works with the above code)
```
polyData = vtk.vtkPolyData()
polyData = reader.GetOutput()
coordinates = []
for i in range(polyData.GetNumberOfPoints()):
coordinates.append(polyData.GetPoint(i))
```
will create a list of coordinates for each point
based on: [https://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataGetPoint](https://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataGetPoint)
---
### Author:  [@jfavre](https://discourse.paraview.org/u/jfavre)
#### Post date: [October 1, 2018, 11:47am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/6 "2018-10-01T11:47:31Z")
the python recipe for your question would be:
reader = GetActiveSource() # make sure you define your active reader.
selection=SelectPoints()
selection.QueryString=“propertyX \<= 0”
selection.FieldType = ‘POINT’
selection.UpdatePipelineInformation()
mySelection = ExtractSelection(Input=reader, Selection=selection)
mySelection.UpdatePipeline()
---
### Author:  [@woodscn](https://discourse.paraview.org/u/woodscn)
#### Post date: [January 12, 2021, 9:04pm UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/7 "2021-01-12T21:04:18Z")
@cory.quammen
This seems relevant to the issue I was having with python state files.
---
### Author:  [@theodorebaltis](https://discourse.paraview.org/u/theodorebaltis)
#### Post date: [January 14, 2021, 3:33am UTC](https://discourse.paraview.org/t/using-find-data-aka-extract-selection-with-python-scripting/562/8 "2021-01-14T03:33:07Z")
I posted about this recently myself (I searched but did find this thread):
[https://discourse.paraview.org/t/query-selection-not-captured-in-python-state-file/6182](https://discourse.paraview.org/t/query-selection-not-captured-in-python-state-file/6182)
But I was able to figure out the code needed because I found out that the query selection **is** caught by an incremental trace.
I was using 5.9.0 RC3.