# Center of mass , (center of data)

Hi all ,
I have a set of 3d points that rapresent atoms in a macro molecule , the atoms mass is the same for each atoms in the molecule, there is a way in paraview to found the center of a certain number of point that rapresent my data in a VTK polydata file ? there is no information about mass , I need just to find out the geometric center of the set of 3d points
How can I do that ?

there is not a tools … like filter to compute that points ?

What about `CellCenters` filter?

@mwestphal I believe the user is asking for the center point of the dataset, not the center point of individual cells.

I believe the filter to do this doesn’t exist. However, you can easily build one. The tools for this are found in the tips and tricks post here: Pointing the camera at the center of a dataset using Python. What you are asking for is the center of the bounds.

yes I need to find the center of the points not the center of cell ! I need to know the coordinate of the center not just to center the camera is it possible ?

You will need to implement that as a Programmable Filter.
https://www.paraview.org/Wiki/Python_Programmable_Filter

I’m have not idea of how to implement … may give me an help ?

The following steps should get you the center of mass (being the average of a set of equally weighted points) without having to write a programmable filter. (It will give you the coordinates but not draw them in the 3D view.)

1. Add the `Calculator` filter.
1.a. Set the `Result Array Name` to `position`
1.b. Set the expression (the text box right above the calculator buttons) to `coords`.
1.c Hit `Apply`. (This will create a field named `position` containing the coordinates of each point.)
2. Run the `Descriptive Statistics` filter. `Apply`.

Once run, the `Descriptive Statistics` filter will open up a spreadsheet view showing statistics like mean, min, max, etc. The mean for `position_0` (X), `position_1` (Y), and `position_2` (Z) should give the center of gravity of your molecule. (That is, if I understand your problem correctly.)

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