# Confidence Threshold for feature-classifier classify-sklearn

**URL:** https://forum.qiime2.org/t/confidence-threshold-for-feature-classifier-classify-sklearn/18881
**Category:** User Support
**Tags:** taxonomy
**Created:** [March 16, 2021, 8:12pm UTC](https://forum.qiime2.org/t/confidence-threshold-for-feature-classifier-classify-sklearn/18881 "2021-03-16T20:12:04Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![amin](https://forum.qiime2.org/user_avatar/forum.qiime2.org/amin/32/9685_2.png) [@amin](https://forum.qiime2.org/u/amin)
#### Post date: [March 24, 2021, 3:42pm UTC](https://forum.qiime2.org/t/confidence-threshold-for-feature-classifier-classify-sklearn/18881/6 "2021-03-24T15:42:13Z")

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> [@amin](#):
>
> QIIME 2. 2021.2

Thanks a lot for your prompt reply. At last, I successfully trained classifier [fun\_classifier\_21.qza](https://forum.qiime2.org/uploads/short-url/x0U4GOGHdCjpEGTEqFlbmjIjsKf.qza) (4.6 MB) in QIIME 2. 2021.2 but when I am testing with my representative sequences [rep-seqs.qza](https://forum.qiime2.org/uploads/short-url/A64ovv6DG67LBEgNlAWYcGOsAbs.qza) (2.0 MB), it’s giving me the following error.

Command I used:  
qiime feature-classifier classify-sklearn --i-classifier fun\_classifier\_21.qza --i-reads rep-seqs.qza --o-classification taxonomy.qza

Error:  
File "/usr/miniconda3/envs/qiime2/lib/python3.6/site-packages/q2\_feature\_classifier/\_skl.py", line 81, in \_predict\_chunk\_with\_conf  
classes = [cls for cls in classes if cls[0].pop(0) == level]  
File "/usr/miniconda3/envs/qiime2/lib/python3.6/site-packages/q2\_feature\_classifier/\_skl.py", line 81, in   
classes = [cls for cls in classes if cls[0].pop(0) == level]  
IndexError: pop from empty list

Plugin error from feature-classifier:

pop from empty list

Potential Cause:  
From the previous [post](https://forum.qiime2.org/t/classify-sklearn-plugin-error-from-feature-classifier-pop-from-empty-list/14074/3) I suspect it is a formatting issue of database, I really really appreciate your kind help on this matter.

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