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#!/usr/bin/env python
# Python example script that uses the vtkRIinterface to create an instance of the
# R interpreter and pass it some data, modify the data in R, and pass the result
# back to VTK.
# VTK must be built with VTK_USE_GNU_R turned on for this example to work!
from __future__ import print_function
from vtk import *
import math
if __name__ == "__main__":
# Create a character buffer to store R output echoed to the terminal
Routput_buffer = 1000*' '
# Create an instance of the R interpreter. Note, rinterface is not a VTK pipeline object.
rinterface = vtkRInterface()
# Create an array of 10 doubles in VTK and fill it with some data
darray = vtkDoubleArray()
for d in range(0, 10):
darray.InsertNextValue(math.sqrt(d));
# Tell R to store its terminal output in our python buffer
rinterface.OutputBuffer(Routput_buffer, len(Routput_buffer))
# Copy the array of doubles into the R interpreter as a matrix called d, with 10 rows and 1 column.
rinterface.AssignVTKDataArrayToRVariable(darray, "d")
# Execute R command to echo contents of d to the terminal.
rinterface.EvalRscript("d",1)
# Execute a command on the R interpreter to create a matrix b with 10 rows and 1 column.
rinterface.EvalRscript("b = matrix(sqrt(10:19),10,1)",1)
# Execute a command on the R interpreter to column append b to d.
rinterface.EvalRscript("d = cbind(d,b)",1);
# Copy matrix d from R back to VTK as an array of doubles in bdarray.
bdarray = rinterface.AssignRVariableToVTKDataArray("d")
# Display the contents of bdarray.
print("\n\nContents of bdarray copied to VTK from R\n\n")
for i in range(bdarray.GetNumberOfTuples()):
t = bdarray.GetTuple2(i)
print('%6.4f %6.4f' % (t[0], t[1]))
# Display the contents of R output echoed to the terminal.
print("\n\nOutput of R interpreter\n\n")
print(Routput_buffer)
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