## Is it possible to choose the points where the results are obtained in the postprocess?

**Moderator:** GiD Team

### Is it possible to choose the points where the results are obtained in the postprocess?

I would like to know if it is possible to choose the coordinates where we want to obtain our results. I have seen that there is a filter to choose this in a subdomain but these points inside the subdomain are chosen by GID, not by the user. For example I would like to obtain my results in a rectangular grid in the subdomain.

### Re: Is it possible to choose the points where the results are obtained in the postprocess?

Probably you are talking about the macros tool: 'List some filtered results', or the command 'list entities'.

These tools allow only select existing entities (nodes or elements, and show the results defined over them)

It is not possible in these tools to select a generic 'xyz coordinate' and interpolate the value of some result for this coordinate

On the other hand other tools like the tool to draw a graph of the result on a point along the time step

Graphs->Point evolution

allow to specify an existing node (selection with Join)

or a new coordinate (selection with NoJoin) and then the values are interpolated to this xyz location from known values 'on nodes' or 'on gauss points'

Or if do you do cuts (and convert them to sets to become a 'standard mesh', there is a variable to do it automatically) then new nodes will be created in the intersection with the edges of cutted mesh. Results will be calculated by interpolation in these new nodes of the cut set (and could be listed then)

These tools allow only select existing entities (nodes or elements, and show the results defined over them)

It is not possible in these tools to select a generic 'xyz coordinate' and interpolate the value of some result for this coordinate

On the other hand other tools like the tool to draw a graph of the result on a point along the time step

Graphs->Point evolution

allow to specify an existing node (selection with Join)

or a new coordinate (selection with NoJoin) and then the values are interpolated to this xyz location from known values 'on nodes' or 'on gauss points'

Or if do you do cuts (and convert them to sets to become a 'standard mesh', there is a variable to do it automatically) then new nodes will be created in the intersection with the edges of cutted mesh. Results will be calculated by interpolation in these new nodes of the cut set (and could be listed then)

### Re: Is it possible to choose the points where the results are obtained in the postprocess?

Thank you very much for your answer. I have chosen the second option since I need a list of the results.

However, I can find linear elements belonging to a cut of a surface, but the nodes of these elements still are in arbitrary positions. Are there any way to obtain and to list these results in equispaced nodes?

However, I can find linear elements belonging to a cut of a surface, but the nodes of these elements still are in arbitrary positions. Are there any way to obtain and to list these results in equispaced nodes?

### Re: Is it possible to choose the points where the results are obtained in the postprocess?

I don't know any direct option to obtain the result on your wanted collection of coordinates.

some other possibilities that could be interesting to you:

create a graph of the result along the segment joining two coordinates (Line graph)

menu:Window->View graphs...

Create tab: Line graph, select the axis and enter the two coordinates.

and then based on this graph (that has its nodes on the cuts with edges) you can create a second graph sampled on equi-spaced interpolation points

menu:Window->Create graphs...

select the first graph, and as operator CatmullRomSpline

then this graph will have x-equi-spaced coordinates.

By default it is using 20 equi-spaced points, you can change it clicking the 'Options' button below the CatmullRomSpline option

then you can get the X-Y values of the graph from Window->View graphs...

Options tab: select the graph and click the 'Show table' button and use copy/paste of a selection of cells, or write the graphs to file

Or in last 14.1.0d developer version, in the 'Plot graph' tab can right-click on a graph, and in the contextual menu select 'Clipboard copy graph' (could paste it in Excel)

Other possible trick is to write a macro script in Tcl that for the collection of xyz points you want

1-automatically create a 'Point evolution' graph

2-select the first point of this graph (in case that there are time steps and the graph has more than one point) and store in some Tcl variable

3-delete the auxiliary graph.

and show the values you want in a message window.

some other possibilities that could be interesting to you:

create a graph of the result along the segment joining two coordinates (Line graph)

menu:Window->View graphs...

Create tab: Line graph, select the axis and enter the two coordinates.

and then based on this graph (that has its nodes on the cuts with edges) you can create a second graph sampled on equi-spaced interpolation points

menu:Window->Create graphs...

select the first graph, and as operator CatmullRomSpline

then this graph will have x-equi-spaced coordinates.

By default it is using 20 equi-spaced points, you can change it clicking the 'Options' button below the CatmullRomSpline option

then you can get the X-Y values of the graph from Window->View graphs...

Options tab: select the graph and click the 'Show table' button and use copy/paste of a selection of cells, or write the graphs to file

Or in last 14.1.0d developer version, in the 'Plot graph' tab can right-click on a graph, and in the contextual menu select 'Clipboard copy graph' (could paste it in Excel)

Other possible trick is to write a macro script in Tcl that for the collection of xyz points you want

1-automatically create a 'Point evolution' graph

2-select the first point of this graph (in case that there are time steps and the graph has more than one point) and store in some Tcl variable

3-delete the auxiliary graph.

and show the values you want in a message window.

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