# paraview.simple: get points coordinates from a slice

**URL:** https://discourse.paraview.org/t/paraview-simple-get-points-coordinates-from-a-slice/5438
**Category:** ParaView Support
**Tags:** python
**Created:** [September 28, 2020, 7:59am UTC](https://discourse.paraview.org/t/paraview-simple-get-points-coordinates-from-a-slice/5438 "2020-09-28T07:59:33Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![ragloo](https://discourse.paraview.org/user_avatar/discourse.paraview.org/ragloo/32/5043_2.png) [@ragloo](https://discourse.paraview.org/u/ragloo)
#### Post date: [September 28, 2020, 7:59am UTC](https://discourse.paraview.org/t/paraview-simple-get-points-coordinates-from-a-slice/5438/1 "2020-09-28T07:59:33Z")

</div>

Hello,

I’m trying to obtain the points coordinates of a slice filter from OpenFOAM data without luck.  
Here what I’ve tried so far

### Extract data from a plane example (file is also attached) [test\_mpl.py](https://discourse.paraview.org/uploads/short-url/4KQYoQu4uYhIZFx3VyAur9649fA.py) (2.0 KB)

import os

import numpy as np  
import matplotlib.pyplot as plt

from paraview.simple import \*  
from vtk.util import numpy\_support as npvtk

def plane\_points(plane\_data, verbose=False):  
“”"Extract the Cartesian points coordinates (x,y,z) of the triangulated plane

```
Parameters
----------
plane_data: Paraview slice object

Return
------
x,y,z: arrays of floats
       Cartesian coordinates of the points in the plane
"""

# Get the number of points
nb_points = plane_data.GetNumberOfPoints()

# Put the points coordinates in x, y and z arrays
x_list = []
y_list = []
z_list = []

for i in range(nb_points):
    coord = plane_data.GetPoint(i)
    xx, yy, zz = coord[:3]
    x_list.append(xx)
    y_list.append(yy)
    z_list.append(zz)

x = np.array(x_list)
y = np.array(y_list)
z = np.array(z_list)

# Display some information on the triangulation points
if verbose:
    print("Number of points:", nb_points)
    print("xrange: [{0:5.3f}, {1:5.3f}]".format(x.min(), x.max()))
    print("yrange: [{0:5.3f}, {1:5.3f}]".format(y.min(), y.max()))
    print("zrange: [{0:5.3f}, {1:5.3f}]".format(z.min(), z.max()))

# Return the points coordinates of the triangulated plane
return x, y, z

```

#### create a new ‘OpenFOAMReader’

pipeCyclicfoam = OpenFOAMReader(FileName=’./pipeCyclic/pipeCyclic.foam’)  
pipeCyclicfoam.MeshRegions = [‘internalMesh’]  
pipeCyclicfoam.CellArrays = [‘U’, ‘epsilon’, ‘k’, ‘nut’, ‘p’]

#### create a new ‘Slice’

slice1 = Slice(Input=pipeCyclicfoam)  
slice1.SliceType = ‘Plane’  
slice1.HyperTreeGridSlicer = ‘Plane’  
slice1.SliceOffsetValues = [0.0]

#### Properties modified on slice1.SliceType

slice1.SliceType.Origin = [5.0, 0.0, 0.0]  
slice1.SliceType.Normal = [1.0, 0.0, 0.0]

plane\_data = servermanager.Fetch(slice1)

#### Extract the cartesian coordinates of the triangulation points

x,y,z = plane\_points(plane\_data, verbose=False)

### I got this error message:

```
in plane_points(plane_data, verbose)
     31 
     32 for i in range(nb_points):
---> 33 coord = plane_data.GetPoint(i)
     34 xx, yy, zz = coord[:3]
     35 x_list.append(xx)

AttributeError: 'vtkmodules.vtkCommonDataModel.vtkMultiBlockDataSet' object has no attribute 'GetPoint'

```

Any idea ?  
I’m stuck ☹

Many thanks !

---

<div class="post-metadata">

### Author: ![theodorebaltis](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/t/e480ec/32.png) [@theodorebaltis](https://discourse.paraview.org/u/theodorebaltis)
#### Post date: [September 28, 2020, 2:57pm UTC](https://discourse.paraview.org/t/paraview-simple-get-points-coordinates-from-a-slice/5438/2 "2020-09-28T14:57:43Z")

</div>

You’re working with a MultiBlockDataSet so you’ll have to either:

1. Work down to a leaf node using `mbds.GetBlock(i)` and then use `leaf_node.GetPoint(i)` or create an iterator to more easily get to the leaf nodes, something like:

```python
itero = plane_data.NewIterator()
itero.SetVisitOnlyLeaves(1)
itero.InitTraversal()
while not itero.IsDoneWithTraversal():
    obj = itero.GetCurrentDataObject()
    nb = obj.GetNumberOfPoints()
    for i in range(nb):
        obj.GetPoint(i)
        ....
    itero.GoToNextItem()

```

1. Use a `MergeBlocks` filter before `Fetch` to create a single dataset from your MBDS, which you can then directly operate on as you were trying before

---

<div class="post-metadata">

### Author: ![ragloo](https://discourse.paraview.org/user_avatar/discourse.paraview.org/ragloo/32/5043_2.png) [@ragloo](https://discourse.paraview.org/u/ragloo)
#### Post date: [October 1, 2020, 8:03pm UTC](https://discourse.paraview.org/t/paraview-simple-get-points-coordinates-from-a-slice/5438/3 "2020-10-01T20:03:09Z")

</div>

It works, many many thanks !