Using Python scripting to plot integration of a variable over a line versus time in ParaView

Question

I have some OpenFOAM simulation results (you may use the official can.ex2 model which can be downloaded from here). What I want to do is:

open a file, load the original data as decomposed case (which can't be applied to the case above)
apply a Calculator filter one a specific variable (e.g. DISP*3.14*coordsX, I used 3.14 because for the love of god I can't find Pi!)
apply filter plot over line [x1,y1,z1] to [x2,y2,z2]
integrate the output of 2 over the line defined in 3 in each time step
plot the result of 4 over time

I would appreciate if you could help me know how I can write a Python script to do this.

For 2: from math import pi. It's not clear what kind of file you're using. If it's csv-like, you can use the csv module in the standard library. — GeorgeG
– GeorgeG, Commented Sep 6, 2018 at 14:24
@GeorgeG In Python I know how to use Pi, however if you check the ParaView Calculator filter property section there are no pi. of course when in Python this issue would be resolved. Unless ParaView API accepts expressions as strings... — Foad S. Farimani
– Foad S. Farimani, Commented Sep 6, 2018 at 14:28
@GeorgeG no problem. I haven't used the python scripting in Parview either. I couldn't even find a good 'for dummies' example. — Foad S. Farimani
– Foad S. Farimani, Commented Sep 6, 2018 at 14:39

Cory Quammen · Accepted Answer · 2018-09-07 01:52:47Z

1

The easiest way to write a Python script to do this is to use ParaView's Python Trace capabilities. Basically, you start a trace and then run through the actions you've listed in the Paraview user interface. ParaView translates your actions into a Python script that you can save and modify after stopping the trace. See Section 1.6.2 of the ParaView Guide for more information. It is probably the single best way to learn about Python scripting for ParaView.

answered Sep 7, 2018 at 1:52

Cory Quammen

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6 Comments

Foad S. Farimani Over a year ago

Thanks for the post. I will read that section, though I still have issues with VTK!

Foad S. Farimani Over a year ago

According to the Guide there must be a Python shell in the Tools menu. I can't find it though. it is not there!

Foad S. Farimani Over a year ago

Found the Python shell. it is in the View menu. For the record on mac there is this nice feature on Help menu where one can search for commands and selecting the item a blue arrow shows the exact place. Wonder why this feature is not on Windows GUI!

Foad S. Farimani Over a year ago

I tried your suggestion to do all the steps once via GUI and trace. I also used @mathieu-westphal method here to interact with ParaView GUI. However the result is not what I expect as can be seen in the image in the gist. It opens all the pans but does not apply any of the filters! I would appreciate if you could help me know what is wrong and how I can solve it.

Foad S. Farimani Over a year ago

I also tried removing the Connect("localhost") and loading the python script from Menu>Macro>Add new macro it shows the first step but again it does not apply the rest. please see paraview_GUI_result_2.png

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