I have an xml file of force plate positions that looks like this:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<Positions>

  <Device name="ForcePlate">
    <ParamListGroup name="">
      <ParamList name="Plate1">
        <Param name="Position_X" value="0.25000000000000006"/>
        <Param name="Position_Y" value="0.23000000000000007"/>
        <Param name="Position_Z" value="0"/>
      </ParamList>
      <ParamList name="Plate2">
        <Param name="Position_X" value="-0.41000000000000009"/>
        <Param name="Position_Y" value="0.090000000000000024"/>
        <Param name="Position_Z" value="0"/>
      </ParamList>
    </ParamListGroup>
  </ParamDefinitionList>

</Positions>

I want to rotate the x and y positions about the z-axis by 90 degrees so that the final xml looks like this:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<Positions>

  <Device name="ForcePlate">
    <ParamListGroup name="">
      <ParamList name="Plate1">
        <Param name="Position_X" value="0.23000000000000007"/>
        <Param name="Position_Y" value="-0.25000000000000006"/>
        <Param name="Position_Z" value="0"/>
      </ParamList>
      <ParamList name="Plate2">
        <Param name="Position_X" value="0.090000000000000024"/>
        <Param name="Position_Y" value="0.41000000000000009"/>
        <Param name="Position_Z" value="0"/>
      </ParamList>
    </ParamListGroup>
  </Device>

</Positions>

My code looks like this:

import numpy as np
import xml.etree.ElementTree as ET
import os

tree = ET.parse(os.path.relpath(r"C:Usersnpires.OMGOneDrive - OMG PLCWork ProjectsNexus Insight WebinarJohnrotate xcp testtest.xml"))

root = tree.getroot()

# Import the positional data
pos_x_string = [element.attrib["value"] for element in root.findall("Device/ParamListGroup/ParamList/Param")
                                            if element.attrib["name"] == "Position_X"]

pos_y_string = [element.attrib["value"] for element in root.findall("Device/ParamListGroup/ParamList/Param")
                                            if element.attrib["name"] == "Position_Y"]

pos_z_string = [element.attrib["value"] for element in root.findall("Device/ParamListGroup/ParamList/Param")
                                            if element.attrib["name"] == "Position_Z"]

# Get the number of plates
plate_num = len(set(pos_x_string))

# Convert the strings into floats
pos_x = [float(num) for num in pos_x_string]
pos_y = [float(num) for num in pos_y_string]
pos_z = [float(num) for num in pos_z_string]

# Combine the plates into their XYZ positions
pos = {plate:
       np.array([[pos_x[plate], pos_y[plate], pos_z[plate]]]).T
       for plate in range(plate_num)}

# Define the rotation matrix
rotation_matrix = np.array([[0, 1, 0], [-1, 0, 0], [0, 0, 1]])

# Define the output matrix
pos_rotated = {plate: np.matmul(rotation_matrix, pos[plate])
               for plate in range(plate_num)}

# Define the output
output = {"Position_X": [str(pos_rotated[plate][0][0])for plate in range(plate_num)],
          "Position_Y": [str(pos_rotated[plate][1][0]) for plate in range(plate_num)],
          "Position_Z": [str(pos_rotated[plate][2][0]) for plate in range(plate_num)]}

# Update the XML
for plate in range(plate_num):
    for position, element in zip(output["Position_X"], root.findall("Device/ParamListGroup/ParamList/Param")):
        if element.attrib["name"] == "Position_X":
            element.set("value", output["Position_X"][plate])

for plate in range(plate_num):
    for position, element in zip(output["Position_Y"], root.findall("Device/ParamListGroup/ParamList/Param")):
        if element.attrib["name"] == "Position_Y":
            element.set("value", output["Position_Y"][plate])

for plate in range(plate_num):
    for position, element in zip(output["Position_Z"], root.findall("Device/ParamListGroup/ParamList/Param")):
        if element.attrib["name"] == "Position_Z":
            element.set("value", output["Position_Z"][plate])

# Write to the XML
_ = tree.write(os.path.relpath(r"C:Usersnpires.OMGOneDrive - OMG PLCWork ProjectsNexus Insight WebinarJohnrotate xcp testtest.xml"))

I can do almost everything. I’m just falling at the final hurdle of updating the XML with the new values