# Retrieving SegmentationStatistics from Large Datasets Using 3D Slicer API
**URL:** https://discourse.slicer.org/t/retrieving-segmentationstatistics-from-large-datasets-using-3d-slicer-api/37924
**Category:** Development
**Tags:** statistics, segmentations, segment-editor, api, segmentation, python, 3d-model
**Created:** [August 17, 2024, 6:05am UTC](https://discourse.slicer.org/t/retrieving-segmentationstatistics-from-large-datasets-using-3d-slicer-api/37924 "2024-08-17T06:05:22Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@JoshOnichino](https://discourse.slicer.org/u/JoshOnichino)
#### Post date: [August 17, 2024, 6:05am UTC](https://discourse.slicer.org/t/retrieving-segmentationstatistics-from-large-datasets-using-3d-slicer-api/37924/1 "2024-08-17T06:05:22Z")
Hello! I a healthcare researcher working on medical image segmentation. I am hoping to automate the retrieval of SegmentationStatistics tables using 3D Slicer’s Python API. However, when I was developing my program, I ran into an issue with the code below.
```
volume_path = os.path.join(input_directory, filename, f'{filename}.nrrd')
segmentation_path = os.path.join(input_directory, filename, f'{filename}_corrected.seg.nrrd')
volume_node = slicer.util.loadVolume(volume_path)
segmentation_node = slicer.util.loadSegmentation(segmentation_path)
segmentStatisticsLogic = SegmentStatistics.SegmentStatisticsLogic()
segmentStatisticsLogic.getParameterNode().SetNodeReferenceID("Segmentation", segmentation_node.GetID())
segmentStatisticsLogic.getParameterNode().SetNodeReferenceID("ScalarVolume", volume_node.GetID())
segmentStatisticsLogic.computeStatistics()
```
When I run the above, the final line of code throws an Attribute Error
(AttributeError: ‘NoneType’ object has no attribute ‘GetParentTransformNode’). I looked into the API source code to try to find the root of the error and found that the error comes from the beginning of the computeStatistics method.
```
def computeStatistics(self):
"""Compute statistical measures for all (visible) segments"""
self.reset()
segmentationNode = slicer.mrmlScene.GetNodeByID(self.getParameterNode().GetParameter("Segmentation"))
transformedSegmentationNode = None
try:
if not segmentationNode.GetParentTransformNode() is None:
...
```
It seems that the segmentationNode is None, but I am not sure why. Is there an error with the way that I loaded the files? Or is there something else I am not considering?
I am new to 3D Slicer (and segmentation, at large) so any insight into this would be a huge help! Thank you very much in advance for your time and consideration and take care.
---
### Author:  [@chir.set](https://discourse.slicer.org/u/chir.set)
#### Post date: [August 17, 2024, 8:14am UTC](https://discourse.slicer.org/t/retrieving-segmentationstatistics-from-large-datasets-using-3d-slicer-api/37924/2 "2024-08-17T08:14:15Z")
> [@JoshOnichino](#):
>
> `self.getParameterNode().GetParameter("Segmentation")`
It seems that the parameter node of your class does not have a parameter named “Segmentation”. You may be confusing with the parameter node of segmentStatisticsLogic.
---
### Author:  [@JoshOnichino](https://discourse.slicer.org/u/JoshOnichino)
#### Post date: [August 17, 2024, 3:23pm UTC](https://discourse.slicer.org/t/retrieving-segmentationstatistics-from-large-datasets-using-3d-slicer-api/37924/3 "2024-08-17T15:23:10Z")
Thank you very much for your response! I took a dive into the source code ([Slicer/Modules/Scripted/SegmentStatistics/SegmentStatistics.py at main · Slicer/Slicer · GitHub](https://github.com/Slicer/Slicer/blob/main/Modules/Scripted/SegmentStatistics/SegmentStatistics.py#L355)) and found out that I was indeed confusing the logic.
Essentially, the error came from a mistake in the way the parameters belonging to the node were set.
Incorrect Code:
```auto
segmentStatisticsLogic.getParameterNode().SetNodeReferenceID("Segmentation", segmentation_node.GetID())
segmentStatisticsLogic.getParameterNode().SetNodeReferenceID("ScalarVolume", volume_node.GetID())
```
Correct Code:
```auto
segmentStatisticsLogic.getParameterNode().SetParameter("Segmentation", segmentation_node.GetID())
segmentStatisticsLogic.getParameterNode().SetParameter("ScalarVolume", volume_node.GetID())
```
So, SetParameter is the correct method to use since I could not find SetNodeReferenceID as a method for SegmentStatisticsLogic in the source code linked above.
Thanks again and take care!