# pybedtools.bedtool.BedTool.filter

BedTool.filter(func, *args, **kwargs)

  Filter features by user-defined function.

  Takes a function func that is called for each feature in the `BedTool` object and returns only those for which the function returns True.

  args and **kwargs are passed directly to *func.

  Returns a streaming BedTool; if you want the filename then use the .saveas() method.

      >>> a = pybedtools.example_bedtool('a.bed')
      >>> subset = a.filter(lambda b: b.chrom == 'chr1' and b.start < 150)
      >>> len(a), len(subset)
      (4, 2)

  so it has extracted 2 records from the original 4.