Note

Click here to download the full example code

# Add Cell Connectivity To Points¶

Example for `PVGeo.filters.AddCellConnToPoints`

This filter will add **linear** cell connectivity between scattered points.
You have the option to add `VTK_LINE`

or `VTK_POLYLINE`

connectivity.
`VTK_LINE`

connectivity makes a straight line between the points in order
(either in the order by index or using a nearest neighbor calculation).
The `VTK_POLYLINE`

adds polyline connectivity between all points as one
spline (either in the order by index or using a nearest neighbor calculation).

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```
import numpy as np
import pyvista
from PVGeo import points_to_poly_data
from PVGeo.filters import AddCellConnToPoints
```

First, lets generate some points which we’d like to connect

```
def path1(y):
"""Equation: x = a(y-h)^2 + k"""
a = - 110.0 / 160.0**2
x = a*y**2 + 110.0
idxs = np.argwhere(x>0)
return x[idxs][:,0], y[idxs][:,0]
x, y = path1(np.arange(0.0, 200.0, 25.0))
zo = np.linspace(9.0, 11.0, num=len(y))
coords = np.vstack((x,y,zo)).T
# Shuffle points to demonstrate value of Nearest Neighbor
np.random.shuffle(coords)
# Make a VTK data object for the filter to use
vtkPoints = points_to_poly_data(coords)
```

## Apply the Filter¶

Now that you have the points generated, lets go ahead and apply
the **Add Cell Connectivity To Points** filter from
*Filters->PVGeo: General Filters->Add Cell Connectivity To Points*.
The output data should look really wacky and incorrectly built like the image
below; this is good.

```
line = AddCellConnToPoints().apply(vtkPoints)
p = pyvista.Plotter()
p.add_mesh(line, line_width=5, point_size=10)
p.show()
```

Out:

```
[(260.7157668726004, 274.0556106226004, 209.0556106226004),
(61.66015624999999, 75.0, 10.0),
(0.0, 0.0, 1.0)]
```

Remember that in the script given above we shuffle the points to demonstrate
that the points make a useable line but we need to reconstruct the order of the
points. We do this by using the *Use Nearest Nbr Approx* checkbox; this will
ensure that a useable path is generate from the points.
Go ahead and use the `nearest_nbr`

argument for the algorith.
Now it looks good (see image below)!

```
# Use the filter: Here is vtkPolyData containing the connected line:
line_o = AddCellConnToPoints(nearest_nbr=True).apply(vtkPoints)
p = pyvista.Plotter()
p.add_mesh(line_o, line_width=5, point_size=10)
p.show()
```

Out:

```
[(260.7157668726004, 274.0556106226004, 209.0556106226004),
(61.66015624999999, 75.0, 10.0),
(0.0, 0.0, 1.0)]
```

**Total running time of the script:** ( 0 minutes 0.597 seconds)