Unmatch raw reads number that exporting from DADA2 to import to Ampvis2 (the same ASV table)

Question

[phxu6780]

Hi. I did dada2 to export ASV table and taxonomy table, sequence files. Then I combine the asv table and taxonomy table, and import these tables into ampvis2 to do further analysis. But the numbers of reads in the same sample file are not matching.

For example, in dada2, after final step of nonchim filtering, the raw reads in one sample is 5145. But in summary or amp_alphdiv command, the raw reads of the same sample is lower, which is 4931. This happen to all the samples, with hundreds to even more than one thousand lower in ampvis2. I wonder is it because the way of ampvis2 counting raw reads is different? Hope someone knows it.