[Paraview] How to execute the Plot Over Line with a Python script and export to CSV

[Luca Giannelli]

Howdy.

I have been looking through the Internet to find a solution for how to have
the Plot over line
executed automatically through a Python script. I was able to find some
sources here on the
Paraview mailing list but nobody reporting a fully functional script (at
list for my case).
So I will share what I wrote to help those people that will surely come up
with the same problems
I had. What does the script do:

- execute a PlotOverLine filter
- export the results in a CSV file
- execute a subsequent second filter directly after the first
- export this to a separate file

I know it may sound an easy job and I know it is not by any means a
"perfect" solution.... but
the code is heavily commented so I think it can surely work well as the base
for further
development for other people.

Good work.

Luca

-----------------------------------------------------------------------------
-----------------------------------------------------------------------------

# First of all, I created this script because I needed to execute the
probing with
# the Plot Over Line filter on 9 points for each time step in a long
simulation with
# the OpenFOAM CFD tool; that kind of thing that you cannot do by hand.
# This is such a dumb script that you can of course modify it as you like to
suit your needs!
# That's Open Source...!
#
# @@ IMPORTANT NOTICE @@
#
# If you are running Paraview using the binaries provided by the Ubuntu
repos, it is
# very likely that you don't have full python support due to the lack of
some functions
# here and there in the provided installation.
# THUS, THIS SCRIPT WON'T RUN!!
# The obvious work around is to uninstall the Ubuntu version and build from
source the
# last stable. This was tested using Ubuntu 11.04 and Paraview 3.8.0 32bit.
#
# Luca Giannelli


import os
try: paraview.simple
except: from paraview.simple import *
paraview.simple._DisableFirstRenderCameraReset()

# If you want to create a set of following operations and save the
# results in different locations, you can manage the folders with
# this code section.
# Just write the path to your folder without forgetting the quotes "".

if not os.path.exists("YOUR_WORK_DIR_GOES_HERE"):
  os.makedirs("YOUR_WORK_DIR_GOES_HERE")

# you can add all the folders that you like in this way by copying this
# check code and inputting the new names.

#
-------------------------------------------------------------------------------
# Moving to the core of the script instuctions for the execution of
PlotOverLine
#
-------------------------------------------------------------------------------

# Let's first identify the source to which we want to execute the P-O-L on:
# This "fotobioreattore_foam" is just the name that I used and you can
change
# it to whatever you like. In the same way, you must provide as a variable
in
# the FindSource, the name of the first module in the stack of your very
own
# case for the script to work. For example:
#
# my_case = FindSource("THE_NAME_OF_YOUR_CASE_GOES_HERE")
fotobioreattore_foam = FindSource("fotobioreattore.foam")

# Now set the source you just defined, as the active one so that the P-O-L
filter
# will be executed on that without need of any other definition. Example:
#
# SetActiveSource(my_case)

SetActiveSource(fotobioreattore_foam)

# Create the first P-O-L, set the extremes of the line and then commit to
render
PlotOverLine2 = PlotOverLine( Source="High Resolution Line Source" )
DataRepresentation7 = Show()

PlotOverLine2.Source.Point1 = [0.0, 0.0, 0.0]
PlotOverLine2.Source.Point2 = [0.0, 0.0, 0.43]

# This will calculate all the values for all the fileds along the line.
# I was not able to identify how to show only the needed parameters.
# However, it is trivial to run all the files through an "awk" command
# for creating a file with just the needed parameters so I do not really
# felt to spend time on something like this.
# Sorry.

Render()

# The last part of the first batch unit is the definition of a writer for
# the actual CSV file creation.
# The source should be your freshly created PlotOverLine. In my case it is
called PlotOverLine2
source = PlotOverLine2
writer = CreateWriter("YOUR_FILE_NAME_GOES_HERE.csv", source)
writer.FieldAssociation = "Points" # or "Cells"
writer.UpdatePipeline()
del writer

del PlotOverLine2
del fotobioreattore_foam
del DataRepresentation7

#
---------------------------------------------------------------------------------------------------
# I am not really sure if this is needed or not but, you know... better to
safe than sorry. So, with
# this line, the first batch operation is concluded. You will have your CSV
file in your folder
# and you will end up with the PlotOverLine filter selected in the GUI. For
this reason, if you want
# to proceed in the creation of a 2nd P-O-L in the same original source, you
will need to specify
# the active source part again here.
#
---------------------------------------------------------------------------------------------------

# Second batch section. You can use whatever filter you prefer here.... I
just needed to go with another
# P-O-L in another place.

fotobioreattore_foam = FindSource("fotobioreattore.foam")
SetActiveSource(fotobioreattore_foam)


PlotOverLine2 = PlotOverLine( Source="High Resolution Line Source" )

DataRepresentation7 = Show()

PlotOverLine2.Source.Point1 = [-0.0345, 0.0, 0.019]
PlotOverLine2.Source.Point2 = [-0.0345, 0.0, 0.43]

Render()

# The writer again
source = PlotOverLine2
writer = CreateWriter("SECOND_FILE_NAME.csv", source)
writer.FieldAssociation = "Points" # or "Cells"
writer.UpdatePipeline()
del writer

del PlotOverLine2
del fotobioreattore_foam
del DataRepresentation7

# Please continue adding all the filters that you like and exporting the
# results to all the CSV files that you want.
#
# Enjoy!!!!
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