# Convert vtkArray -\> vtkPoints?
**URL:** https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609
**Category:** Support
**Tags:** python
**Created:** [February 3, 2023, 7:58pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609 "2023-02-03T19:58:03Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@rexthor](https://discourse.vtk.org/u/rexthor)
#### Post date: [February 3, 2023, 7:58pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/1 "2023-02-03T19:58:03Z")
It seems (to me) that the data in vtkArray should be similar to vtkPoints. If I read in data, as a numpy array, and convert it to vtk format like:
```python
pd = vtk.vtkPolyData()
g = numpy_to_vtk(my_nice_array)
pd.SetPoints(g)
```
This doesn’t work. I can use something like:
```python
...
pts = vtk.vtkPoints()
for x, y, z in my_nice_array:
pts.InsertNextPoint(x, y, z)
```
But I was wondering if I could somehow convert the output of `numpy_to_vtk` to `vtkPoints`?
---
### Author:  [@Paulo\_Carvalho](https://discourse.vtk.org/u/Paulo_Carvalho)
#### Post date: [February 5, 2023, 2:12pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/2 "2023-02-05T14:12:31Z")
Hello,
> [@rexthor](#):
>
> This doesn’t work.
Can you, please, be more specific? “Does’t work” can mean a lot of different unexpected results when it comes to computer graphics.
regards,
Paulo
---
### Author:  [@marcomusy](https://discourse.vtk.org/u/marcomusy)
#### Post date: [February 5, 2023, 3:28pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/3 "2023-02-05T15:28:42Z")
I guess you can do
```python
pd.GetPoints().SetData(numpy_to_vtk(my_nice_array))
```
---
### Author:  [@rexthor](https://discourse.vtk.org/u/rexthor)
#### Post date: [February 6, 2023, 1:21pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/4 "2023-02-06T13:21:29Z")
First, thanks for the replies.
@Paulo_Carvalho, here is the error that I got:
```auto
TypeError: SetPoints argument 1: method requires a vtkPoints, a vtkTypeFloat64Array was provided.
```
@marcomusy, this is the error that statement generates:
```auto
AttributeError: 'NoneType' object has no attribute 'SetData'
```
Here is the code I ran to get that last error:
```python
import vtk
import numpy as np
from vtk.util.numpy_support import numpy_to_vtk
pd = vtk.vtkPolyData()
g = numpy_to_vtk(np.zeros(5))
pd.GetPoints().SetData(g)
```
---
### Author:  [@Paulo\_Carvalho](https://discourse.vtk.org/u/Paulo_Carvalho)
#### Post date: [February 6, 2023, 2:31pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/5 "2023-02-06T14:31:26Z")
What do you get when you run
```python
pd = vtk.vtkPolyData()
g = numpy_to_vtk(my_nice_array)
pd.SetPoints(g)
```
?
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [February 6, 2023, 2:45pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/6 "2023-02-06T14:45:03Z")
When you create a vtkPolyData, it is empty, so it has no points:
```python
>>> pd = vtk.vtkPolyData()
>>> pd.GetPoints()
None
```
And you can’t call `SetPoints()` with a vtkDataArray, since they’re different types. So what you have to do is create a vtkPoints object from the vtkDataArray, and then call `SetPoints()`.
```python
>>> pd = vtk.vtkPolyData()
>>> points = vtk.vtkPoints()
>>> points.SetData(numpy_to_vtk(my_nice_array))
>>> pd.SetPoints(points)
```
Also note that the vtkDataArray must have 3 components or else this will fail. So make sure the array has the correct shape.
---
### Author:  [@marcomusy](https://discourse.vtk.org/u/marcomusy)
#### Post date: [February 6, 2023, 2:48pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/7 "2023-02-06T14:48:48Z")
i think the problem is that your polydata is still empty, this works:
```python
import vedo
msh = vedo.Mesh("https://vedo.embl.es/examples/data/apple.ply")
pd = msh.polydata()
pts = msh.points()
import vtk
import numpy as np
from vtk.util.numpy_support import numpy_to_vtk
#pd = vtk.vtkPolyData()
g = numpy_to_vtk(np.zeros_like(pts)+pts*2) # whatever..
pd.GetPoints().SetData(g)
#vedo.show(pd)
```
you need to set it with a `vtkPoints` object.
---
### Author:  [@rexthor](https://discourse.vtk.org/u/rexthor)
#### Post date: [February 6, 2023, 3:01pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/8 "2023-02-06T15:01:44Z")
I agree with you guys, that the “points” was empty - it just seemed to me like the vtkPoints is conceptually just an array, I was wondering if there was some way to use the vtk.util function `numpy_to_vtk` to directly load points instead of having to iterate over the rows in the array to add the coordinates … but it looks like the only way to do it is to iterate over the rows.
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [February 6, 2023, 3:05pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/9 "2023-02-06T15:05:11Z")
No, it’s not necessary to iterate over the rows. Both my answer and Marco’s answer demonstrate how to create vtkPoints from a numpy array. It just takes two steps.
---
### Author:  [@rexthor](https://discourse.vtk.org/u/rexthor)
#### Post date: [February 6, 2023, 3:06pm UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/10 "2023-02-06T15:06:39Z")
Ok - sorry, I see that now, thanks!
---
### Author:  [@michaelhogg](https://discourse.vtk.org/u/michaelhogg)
#### Post date: [October 31, 2023, 4:46am UTC](https://discourse.vtk.org/t/convert-vtkarray-vtkpoints/10609/11 "2023-10-31T04:46:10Z")
I like to wrap the polydata object first
```auto
import numpy as np
from vtkmodules.numpy_interface import dataset_adapter as dsa
polydata = dsa.WrapDataObject(vtk.vtkPolyData())
polydata.Points = np.random.random(30).reshape(-1,3)
```