Eval Expression

EvalExpression #

[[step]]
    action = "EvalExpression"
    out_label = "outtag"
    expression = "log(2, mytag + 1)" # log to base 2
    result_type = "numeric" # or bool.

Calculate a fasteval expression on your tags, which you can then pass to .FilterByTag.

You can use any tags previously defined on the molecule as variables in the expression.

Additional, there’s a series of virtual tags available:

  • len_<segment-name> - the length of the specified segment (e.g. len_read1).
  • len_<tag-label> - the length of the specified tag (e.g. len_mytag). For location tags, this is the length of the underlying matched regions (which may change / be lost when reads are truncated - eval before truncation if necessary). For string tags (= ExtractRegex with source=name:...) this is the length of the replaced string.