non-chimeric Feature count - what is all about?

In output FeatureTable table.qzv in Interactive Sample Detail is 'Sample ID' and 'Feature count'. Does 'Feature count' mean ASVs count in certain sample here?
In one of DADA2 output SampleData[DADA2Stats] I have table with sample-id, input, filtered... non-chimeric etc. And 'non-chimeric' value is the same as 'Feature count' mentioned earlier.
I assumed that non-chimeric reads are "good reds" that are used further in the analysis.. Could anyone explain me what exactly is mean by 'Feature Count' ?

Hi @elina2410,

Welcome to the :qiime2: forum!

Great question - feature count can refer to the total number of features observed, or the number of times a specific feature was observed (within a given sample, etc). I would advise against referring to ASVs and features interchangeably however - @Nicholas_Bokulich has a very concise description of the difference between ASVs and features, which you can find here (with further explanation on the general definition of a feature here).

A chimeric read (or split read) means that multiple subsections of a given read align to multiple distinct portions of the genome with little or no overlap. Non-chimeric reads refer to any read that aligns with a continuous portion of the genome (i.e. a 'real' segment of DNA that exists in the wild).

Hope this helps! Cheers :lizard:


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